Design of jogging sportswear for use in tropical countries.docx

Design of jogging sportswear for use in tropical countries
41
Abstract
Joggers experience discomfort due to the production of sweat,
especially in tropical countries with high humidity level and
temperature. Hence, appropriate attires are needed to improve
the level of comfort. The main objective of this project is to
come up with a suitable jogging attire for the mass public in
Singapore, based on climate conditions and consumer
preference. This was firstly done through the understanding of
the mechanism involved in sweat removal in various materials.
Following that, the design concepts of good moisture wicking,
good moisture vapour transport, good thermal conductivity and
ultraviolet (UV) protection were established, and designs based
on a short sleeve top with a pair of shorts were proposed.
Additional features of body posture maintenance and body
odour reduction were also included. Next, the materials
selection process was done based on relevant design concepts
and features. The designs took into consideration the properties
of materials, manufacturing methods and design features that
improve the overall performance of the jogging attire. However,
there are limitations in the proposed design due to the
restrictions in current manufacturing methods. Hence, further
research on more advance manufacturing methods and materials
can be done to improve the functionality.

Table of Contents
1.Introduction1
1.1.Background1
1.2.Purpose and Objectives2
1.3.Scope2
2.Literature Review3
2.1.Climate Conditions of Singapore3
2.2.Thermoregulation of the Body3
2.3.Moisture Wicking5
2.4.Moisture Vapour Transfer in Fabric7
2.5.Thermal Conductivity of Fabric8
2.6.UV Protection8
2.6.1.Construction9
2.6.2.Treatment with UV absorbers9
2.6.3.Fibre Type10
2.6.4.Moisture and Swelling10
3.Design11
3.1.Basic Design Concepts11
3.1.1.Good Moisture Wicking11
3.1.2.Good Moisture Vapour Transport12
3.1.3.Good Thermal Conductivity12
3.1.4.UV Protection13
3.2.Additional Features13
3.2.1.Maintenance of Body Posture13
3.2.2.Reduction in Body Odour14
3.3.Design Outline15
4.Materials17
4.1.Cotton17
4.2.Bamboo Fibre17
4.3.Linen18
4.4.Nylon18
4.5.Polyester18
4.6.Spandex19
4.7.Wool19
4.8.Analysis of Materials19

4.9.Materials Selection22
4.9.1.Materials for the Bulk of Jogging Attire22
4.9.2.Material for Armpit and Inner Thighs Area25
4.9.3.Material for X Posture25
5.Manufacturing Methods26
5.1.Fibre Production26
5.1.1.Polyester blended with cotton fibres26
5.1.2.Spandex Fibres28
5.1.3.Bamboo Fibres28
5.2.Fabric Production Methods31
5.2.1.Warp knitting31
6.Final Design and Dimensions32
7.Evaluations34
7.1.Cost34
7.2.Comfort35
7.3.Protection36
8.Conclusion and Recommendations37
9.References39
List of Figures
Figure 1. Sweat Distribution of Male and Female Runner5
Figure 2. Fibre Length and Cross Section Micrograph of
Regular Polyester7
Figure 3. Fibre Length and Cross Section Micrograph of Silk7
Figure 4. Fibre length and cross section micrograph of silk14
Figure 5. Design of the Top16

Figure 6. Design of the Bottom16
Figure 7. Summary of Benefits of a Polyester-Cotton Blend24
Figure 8. Melt spun process26
Figure 9. Operation of the Cotton Gin27
Figure 10. The Mechanical Processing of Manufacturing
Bamboo Fibres30
Figure 11. Warp Knitted Fabric31
Figure 12. Final Design of the Top33
Figure 13. Final Design of the Bottom34
List of Tables
Table 1. Comparison of the Data of Fibres20
Table 2. Comparison of the properties of Fibres20
Table 3. Fibre Breaking Force and Breaking Tenacity
Comparison28
Table 4. Moisture Wicking Properties of Bamboo Fabric29

i
1. Introduction
1.1. Background
People are becoming more health conscious due to increasing
level of education. More efforts are put in to maintain their
health, such as involving themselves in exercises.
Jogging is by far one of the most popular exercises among
people [1]. The reason for its popularity is that jogging is one
of the easiest and cheapest form of exercises. It is a slow pace
form of running which gives a lower level of stress on the body
when compared to normal running. Due to its simplicity,
specific running attire or gear for jogging are often deemed as
unnecessary. People tend to put on any comfortable attire
available [2]. However, specific jogging attire is in fact
essential for joggers.
Participating in physical activities such as jogging generates
heat as energy is being used up in the process [3]. The body
temperature increases beyond its normal temperature. Excess
heat is regulated by the body and dissipated through the
evaporation of sweat in order to maintain the normal body
temperature [3].
In tropical countries, the hot weather further increases the core
body temperature, resulting in more sweat being produced,
while the high humidity hinders the evaporation of sweat from
the body. Without proper attire, the accumulation of sweat on
the body reduces the sensorial comfort level of the jogger as
they will start to feel wet and clammy [4]. Hence, there is need
to design a proper jogging attire for joggers in the tropical

countries by providing better comfort.
1.2. Purpose and Objectives
The purpose of this project aims to come up with a design for
jogging attire for tropical countries through fulfilling 3
objectives:
1. To establish the functional requirements of jogging attire
through the understanding of the different properties and
manufacturing methods of common fibres used in sports attire
and how they can improve the function of the attire
2. To develop additional features of jogging attire
3. To select materials and manufacturing methods which fit the
functional requirements
1.3. Scope
The targeted audience for the jogging attire will be the general
public and all types of jogger, not just for athletes who are
looking for performance based attire. Hence, affordability of the
attire is what we are closely looking at.
Many types of fibres are available for manufacturing. The
selection of the materials for the design will only be based on
the woven fibres that are readily available in the market.
Clothing made from these fibres can easily produce and are
generally expected to be at lower cost. Attires made this way
can be catered to the general public, establishing a larger
market.
Singapore is selected as the country that our design will be
based on. The reason is that Singapore is one of the developed
countries in the tropical region. In developed country, a higher
level of education has resulted greater level of health

consciousness. Thus, people are increasingly exercising to
maintain their health [1].
2. Literature Review
The literature review focuses on the understanding of the
climate conditions in Singapore, the needs of jogging, and the
properties of fibre that can assist in the removal of body heat.
2.1. Climate Conditions of Singapore
Singapore is a country which is located just 1 degree north of
the equator, having a typical tropical climate [5]. It does not
experience four seasons and the weather is warm and humid all
year round. Due to its location, Singapore experiences uniform
high temperature with average temperature ranges from 25oC to
31oC, high relative humidity (RH) of about 70% to 80% and
large amounts of rainfall [5]. The temperatures can vary from a
minimum of 23-26oC at night to a maximum 31-34oC in the
day. While RH varies from 90% in the morning and 60% in
mid- afternoon, humidity levels can be as high as 100% on rainy
days. Singapore is also a sunny island all year round, exposing
to large amount of ultraviolet (UV) rays, having UV indexes of
about 10 - 13 [6].
2.2. Thermoregulation of the Body
When multiple muscle groups start working together during
jogging, their activities generate large amount of heat. This
increases the temperature of the fluid and blood surrounding the
muscle groups, which eventually spreads to the whole body. The
increase in body temperature is sensed by the central and skin
thermo receptors which send this information to hypothalamus
[7]. The hypothalamus will then try to maintain a constant
internal body temperature of about 37oC by generating an

appropriate response [8]. When the temperature increases
beyond this limit, the hypothalamus in the brain will trigger
vasodilation, the process of dissipating the excess heat
beginning with the heat transfer from muscle tissue to the skin
surface [9]. The diameter of the capillaries near the skin surface
expands to facilitate the increase of blood flow to dissipate the
excess heat.
If the body temperature continues to rise, the next mechanism
for heat dissipation will be triggered through evaporation of
sweat. There are more than 2 million of sweat glands distributed
along the body surface. Each of the glands will produce sweat at
different rates, according to the location of the gland in the
body and are directly under the control of the central nervous
system [8].
Eccrine sweat glands are the major sweat glands that are
distributed under the skin surface, except lips and glans penis
[10]. Evaporative heat loss from eccrine sweat glands is critical
for thermoregulation during exercise and when exposed to hot
environment [11]. Sweat work best at reducing body
temperature when it is evaporated directly under the skin and
release as water vapour, since heat energy needed to evaporate
sweat is extracted from the body and causes the body the
temperature to drop [4]. Only through thermoregulatory
sweating that involves eccrine sweat glands can the body be
effectively cooled at high physical loads.
Past experiment was done by George Havenith and friends,
where they conduct experiment on the sweat distribution during
running in both male and female runners. It showed that for
both sexes, the highest sweat rate was observed in the mid
central back, followed by the chest area and upper arm area as
the lowest sweat rate as seen in Figure 1 [12].

Figure 1. Sweat Distribution of Male and Female Runners [12]
2.3. Moisture Wicking
Moisture wicking is the movement of a liquid along the fibre
without the liquid being absorbed into the fibre [4]. It is
physically, the spontaneous flow of a liquid in a porous
substrate driven by capillary forces. Wicking occurs when
capillary pathways are present on the fibre surface or found
between fibres in a fabric [8]. The process is dependent on the
size and quantity of capillaries in the fibre, fabric, and yarn, as
well as the surface tension of the liquid. The liquid is pulled
into the capillaries by interfacial forces produced by the
capillaries on the fibre surface and the spaces between the
irregular shaped fibres. These interfacial forces are the result of
intermolecular forces of cohesion and adhesion caused by the
surface tension of the liquid and the travelling surface. When
the adhesion forces between liquid and tube surface are greater
than cohesion forces between molecules of the liquid, capillary
action can take place [4]. The liquid will move along the fibre
surface to the outside of the exterior of the fabric where it is
being evaporated.
Absorbent fibres generally tend to have poorer wicking ability
compared to non-absorbent fibres. The reason behind is because
absorbent fibres will swell and close their capillaries when
absorbent fibres are saturated with liquid, thus, preventing
wicking from occurring.
Synthetic fibres also tend to have better moisture wicking
ability when compare to natural fibres [4]. As seen in Figure 2,
synthetic fibres have very regular capillaries, they are linear,
compact and smooth which results in a low contact angle and
hence, high wettability. On the other hand, natural fibres have
very irregular capillaries due to fibre roughness, non-uniform

cross sectional shape and length as seen in Figure 3. This
results in poor capillary action in natural fibres and so poor
moisture wicking capabilities.
Clothing with good moisture wicking ability is required for
sweat removal. However, heat is not removed from the body
during wicking since sweat is transported out to the exterior of
the fabric before it is removed. Evaporation occurs on the fabric
rather than on our skin and so heat is not being removed,
limiting the thermoregulation function of the body.
Figure 2. Fibre Length and Cross Section Micrograph of
Regular Polyester [4]
Figure 3. Fibre Length and Cross Section Micrograph of Silk [4]
2.4. Moisture Vapour Transfer in Fabric [4]
Moisture vapour transfer is related to how well a fabric is able
to transfer a gas rather than a liquid. When sweat is created and
evaporated by the body heat under the surface of the skin,
moisture vapour of sweat forms. It is then passed out of the
fabric and cools the wearer. This function of the fabric is
affected by the air permeability and the cover factor of the
fabric. Fabric with low cover factor and large spaces between
yarns have better air permeability and are more able to perform
the function of transferring moisture vapour.
2.5. Thermal Conductivity of Fabric
Fabrics that are knitted by interloping yarns tend to trap air and
this reduces the thermal conductivity of the fabric, making the
wearer feel hotter as heat is being trapped within the fabrics [8].

This is because air is a very poor conductor of heat as compared
to solid materials. Furthermore, when wearing clothing that is
close to the skin, the individual will feel cooler as no air is
being trapped between the skin and the clothing. Hence, heat
can be transferred faster from the body to the environment.
This situation could be improved if the clothing is wet as water
can help to increase the thermal conductivity of the fabric. In
fact, water has the ability to cool the body 25 times faster than
air [4].
2.6. UV Protection
As mentioned above, Singapore is a country that is exposed to
large amount UV rays, so there is a need to understand the
characteristics of UV rays in order to stay protected. About 48%
of sunlight is visible to human eyes, 46% is in the form of
invisible infrared radiation, and 6% is the invisible ultraviolet
radiation [13]. There are mainly 2 types of UV radiation that is
reaching the earth surface, UVA and UVB. They are both
capable of causing immediate and long-term negative impact to
the human body. UVA makes up about 95% of the solar
radiation that reach the earth surface. It has high penetration
power and is capable of penetrating deeper into the skin
compared to UVB. The UVA is capable of indirect DNA
damage, aging of skin and is also cancer causing [14]. On the
other hand, UVB is mostly absorbed by the ozone layers. The
UVB that reaches the earth is mostly absorbed by the epidermis
of the skin. Although it has low penetration power, it is the
primary cause of skin cancer [14].
When exposed to UV radiation, it can cause chemical reactions
to occur in the skin which can directly or indirectly damage
proteins and DNA, damaging cells or causing them to die off
[14]. Severely damaged cells die off and disassemble, when

happened in large quantities, it appears as the peeling of skin.
Cells that are only partially damaged but are capable of
recovering from the damage continue to live on in the body.
However, they function abnormally and become the basis of
skin cancer. Cancer grows and spreads as these cells continue to
multiply. The damages done by UV radiation are cumulative
over one’s lifetime and can be severe. Hence, there is a need to
protect from it.
The protection of UV in clothing can be done by varying the
construction of the fabric, treatment processing, type of the
material, and wetness.
2.6.1. Construction
Small and tight spaces between threads greatly reduces the
amount of UV rays transmitted [15]. In order to improve the
ultraviolet protection, fabric can be tightly woven or knitted.
Nevertheless, if the clothes were too tight, the material might
stretch and tear, exposing more skin to the sun.
2.6.2. Treatment with UV absorbers
UV absorbers are compounds with strong absorption in the UV
range [16]. They are capable of converting electronic excitation
energy into thermal energy. Electrons in the UV absorbers are
excited to a higher energy state when exposed to UV and the
energy is released as longer wave radiation when it goes back to
the ground state. Effective UV absorber must be capable of
absorbing within the spectrum, remain stable against UV
radiation and be able to dissipate the absorbed energy to avoid
degradation.
2.6.3. Fibre Type
Materials that provide good ultraviolet protection could be used.
The nature of the fibres affects the UV transitivity which in turn
affects the amount of UV protection [16]. Natural fibres tend to
have lower degree of UV protection as they are often damaged

when exposed to UV radiation due to the excitations of the
polymer fibres. Also, natural fibres do not absorb the full range
of UV radiation. Depending on the functional groups present,
synthetic fibres are capable of absorbing UV radiation and are
more stable to thermal excitation. Polyester fibres contain
benzene ring and are able to absorb more in the UVA and UVB
regions than aliphatic polyamide.
2.6.4. Moisture and Swelling
When fibres absorb moisture and become saturated, they tend to
swell. This has 2 effects on UV transmission on the fibre [16].
One is that fibres filled with moisture have reduced scattering
effects as the refractive index is closer to that of the textile
polymer. This allows more UV radiation to be transmitted in the
process. For example, cotton transmits 15- 20% of UV radiation
and this can rise up to more than 50% if the fibre is wet. The
other factor is dependent on the swelling capacity. If swelling
capacity is high, it is possible that the swelling can reduce the
interstices in the fabric, reducing UV transmission. These 2
factors have contradicting effects and proper management is
required to reduce UV transmission.
3. Design
After going through the literature reviews, in this section the
functional requirements, additional features and the design of
jogging attire will be established.
3.1. Basic Design Concepts3.1.1. Good Moisture Wicking
The production of sweat is a basic homeostatic function of the
body to maintain human body temperature when the body
temperature starts to rise during jogging. It is an unavoidable
process that is essential to dissipate the excess body heat.
However, too much sweat produced on the surface of the body

reduces the comfort level of the jogger [4]. When too much
sweat is being produced and evaporation is not fast enough,
they remain as liquid phase on the body, this makes the jogger
feels wet and clammy. This is especially true in tropical
countries like Singapore with RH level of about 70-80 %. High
RH levels in the air results in slower rate of evaporation as the
air is saturated with moisture vapour. Therefore, the ability to
wick moisture away from the body is the most important in the
proposed design. It allows the sweat to be transported away
from the surface of the body to the exterior of the clothing.
Thus, the jogger can feel cool and dry during jogging.
3.1.2. Good Moisture Vapour Transport
When sweat is evaporated from the skin, it changes from liquid
phase to gaseous phase. As this process continues, moisture
vapour concentration in the microclimate between the body and
attire starts to increase. RH levels increase and result in an even
slower rate of evaporation. Sweat cannot be removed effectively
and the jogger will feel uncomfortable due to the accumulation
of the sweat on the body surface. Attires with high air
permeability encourage moisture vapour transport as the
gaseous sweat is allowed to diffuse from the interior to the
exterior and into the air, regulating the RH levels of the
microclimate within.
3.1.3. Good Thermal Conductivity
The proposed attire must also have good thermal conductivity.
During jogging, large amount of heat is being generated by the
body as a result of burning energy. The body core temperature
is further increase with the climate of Singapore as temperatures
are generally high. The body will regulate this temperature
through vasodilation and sweating. In vasodilation, more blood
is pumped to the surface of the skin to allow heat to be lost
through conduction, convection, and radiation. However,
clothing without good thermal conductivity limits the amount of

heat that can be conducted out of the body. Accumulation of too
much heat can be dangerous as it can result in heat injury [3].
Hence, there is a need for good conduction of heat in the attire.
3.1.4. UV Protection
Singapore is a country that has high UV indexes. Therefore, the
proposed attire should provide a minimum level of UV
protection for its user as long term exposure to UV radiation
can cause cancer and damage to the skin. Jogging is a form of
exercise that can be done outdoor, in the day and for a long
period of time. Joggers are constantly being exposed to high
intensity UV radiation during jogging. Furthermore, people who
participate in jogging activities tend to be more health
conscious, they would not want to risk their health by exposing
themselves to too much UV radiation [1]. Hence, it would be
beneficial for jogging attire to be able to protect its user from
exposure to UV radiation.
3.2. Additional Features3.2.1. Maintenance of Body Posture
Improper alignment of the body becomes a concern of everyone
regardless of activities, environment, sex, ages, or occupation
as it will restrict the body function. Without a good body
posture, people can encounter the problem of extra strain on the
ligaments, muscles, and joints which will bring a long-run
problem such as back pain [17]. During jogging, joggers tend to
overlook their body posture. Hence, an additional feature which
can support both shoulders and upper back of the joggers can be
made using the concept of a body posture support. An additional
layer of fibre with good ductility and flexibility can be included
in the attire as shown in Figure 4 to pull the shoulders to align
the back properly.
Figure 4. Fibre length and cross section micrograph of silk [4]

3.2.2. Reduction in Body Odour
While eccrine sweat glands contribute to the thermoregulation,
our body also consist of apocrine sweat glands which are
responsible for producing body odour [18]. Unlike eccrine
sweat glands that can be found in most of the body surfaces,
apocrine sweat gland only exist in a particular part of the body,
which are armpit, eyelid, breast, and the genital region.
Sweat produced by apocrine glands is high in protein. When it
first comes out from the skin, the apocrine sweat is actually
odourless and sterile [18]. Bacteria can break the protein in the
sweat down easily into propionic acid or isovaleric acid,
creating the odour [19]. Fibres that have good air permeability
and resistance to bacteria growth can be used.
3.3. Design Outline
Due to the warm and humid weather conditions, Singaporeans
have the culture of wearing simple and casual clothing which
are suited for the weather conditions [5]. Based on the culture,
the proposed design for the jogging attire would adopt the
concept of a short sleeve round neck shirt and a pair of shorts as
shown in Figure 5 and Figure 6, respectively.
Features included in the design are based on the designing
concepts mentioned above. The most distinct additional feature
is the ‘X Posture’ support as shown in Figure 5. The feature
aims to provide a certain form of support by supplying a force
which pulls the shoulder and the back by incorporating an
elastic fibre into the attire. The fibre will act as a form of
resistance to the jogger when the jogger performs a bad posture.
The second additional feature of the attire aims to reduce body

odour in the armpit and inner thigh areas as seen in Figure 5 and
Figure 6. Body odour is perceived as a form of unpleasant smell
and this may affect the users comfort and personal image, hence
it should be reduced [19].
Figure 5. Design of the Top
Figure 6. Design of the Bottom
4. Materials
In order to make a clear choice of the fibres, a basic
understanding of the fibres, their properties and needs of the
mass public is essential. As affordability is a concern to the
mass public, only fibres readily available in the market were
selected, discussed and compared as they are generally of lower
cost. The fibres being chosen are cotton, bamboo fibre, linen,
nylon, polyester, spandex and wool.
4.1. Cotton
Cotton is a natural fibre which produces a strong and durable
fabric where strength increases when wet [20]. Cotton is
inelastic and has a tendency to wrinkle very easily [21]. It has
good moisture absorbency and, hence, is a comfortable fibre to
be worn, especially in a wet condition [20]. Other advantages of
cotton include the ease of washing and dyeing [22].
4.2. Bamboo Fibre
Bamboo fibre is a natural fibre which is softer than cotton, with

a texture similar to a blend of cashmere and silk. It has much
better moisture absorption and ventilation because the cross-
section of the fibre is filled with various micro-gaps and micro-
holes. Although its moisture absorbency is twice that of cotton,
it shrinks more easily [23]. The natural antibacterial elements in
bamboo fibre help to keep bacteria away, thus preventing odour.
Bamboo fibre can absorb and evaporate sweat very rapidly,
allowing the wearer to feel cool and comfortable. It also shows
a great elasticity of about 20% elongation. Furthermore, the
anti-ultraviolet nature of bamboo fibre has made it suitable for
summer clothing. Lastly, product of bamboo fibre is eco-
friendly and bio-degradable [23].
4.3. Linen [20]
A natural fibre from flax plant that is very strong and
comfortable. Its inelasticity is responsible for the wrinkling of
linen fabrics. In wet condition, flax becomes even more
inelastic and wrinkles more readily while its strength increases.
Linen can only be hand washed and dry cleaned.
4.4. Nylon
Nylon is a synthetic fibre made from by-products of coal/gas
manufacturing [20]. It is a lightweight, strong fibre with high
elasticity [21]. In addition, it also has superior abrasion
resistance, high flexibility and dries quickly [24]. However,
nylon has low moisture absorption and loses strength when wet.
Moreover, nylon tends to experience static clinging, and it has
low thermal stability [25].
4.5. Polyester

Polyester is a light, strong, and durable synthetic fibre made
from by-products of petrol manufacturing [20]. Polyester has
high strength, excellent resiliency, and high abrasion resistance
[24]. Its low moisture absorbency and good moisture vapour
transport also allows the fibre to dry quickly. In addition, its
strength can be retained under both wet and dry conditions [20].
Furthermore, it is very suitable to be blended with natural fibres
and can withstand climatic effects [26].
4.6. Spandex
Spandex is a lightweight synthetic fibre which can be stretched
repeatedly and still retains its original length and shape [24]. It
is stronger, more durable, and has higher retractive force than
rubber [27]. Spandex provides a combination of comfort and fit,
and also prevents bagging, sagging, and abrasion. Furthermore,
it is also resistant to deterioration by body oils and perspiration
[27].
4.7. Wool
Wool is a natural fibre made from sheep. The elasticity of wool
is very good resulting in good wrinkle recovery [20]. It is the
most absorbent fibre used but it dries slowly and is prone to
shrinking. Wool also has low thermal conductivity. It has low
strength and becomes even weaker in wet condition.
Furthermore, it retains odour.
4.8. Analysis of Materials
Data of the properties of the above mentioned materials are
tabulated and compared as seen in Table 1 and 2.

1
Table 1. Comparison of the Data of Fibres [28]
Density
(g/cm3)
Elastic Modulus
(cN/tex)
Moisture Absorption
a. 21˚C/65RH (%)
b. 24˚C/95RH (%)
Water Retention
(%)
Thermal Conductivity (J/m.s.k)
Cotton
1.50-1.54
300-600
a. 7-11
b. 14-18
45-50
0.3-0.5
Linen
1.43-1.52
800-1000
a. 8-10
b. up to 20
50-55
0.3
Nylon
1.14
50-300
a. 3.5-4.5
b. 6-9

10-15
0.2-0.3
Polyester
1.36-1.38
250-400
a. 0.2-0.5
b. 0.80-1.0
3-5
0.2-0.3
Spandex
-
0.3-0.7
a. 0.15-1.5
b. 0.5-1.5
7-11
0.15
Wool
1.32
150-300
a. 15-17
b. 25-30
40-45
0.2
Air permeability
Abrasion resistance
Anti-ultraviolet
Bacterial & Fungus
(biological resistance)
Bamboo Fibre
·
·
·
Excellent
Cotton
·

·
X
Unbleached: low
Linen
·
·
X
Unbleached: low
Bleached: good
Nylon
X
(when thick)
·
X
Good to very good
Polyester
X
·
Very good
Spandex
X
·
X
Generally good
Wool
·
·
X
Good resistance to rotting
Table 2. Comparison of the properties of Fibres
The proposed jogging attire requires good moisture wicking.
Hence the property of moisture absorption is evaluated in Table

1. Fibres having poor moisture absorption tend to have good
moisture wicking ability. This is because when moisture is
absorbed in the fibre, the capillaries for wicking swell and
close, reducing moisture wicking ability.
The moisture absorption here is measured in percentage under
fixed conditions whereby the temperature is 21˚C with a relative
humidity (RH) of 65% and temperature is 24˚C with a RH of
95%. A RH of 100% means that the air is totally saturated with
water vapour. After comparing the values in table 1, the
material with the lowest moisture absorbency is spandex
followed by polyester and nylon. Wool has the best ability to
absorb moisture.
Furthermore, high percentage of water retention would further
decrease the wicking ability as the water being absorbed does
not dry up quickly and retains in the fibre. As seen from the
table, polyester and spandex are the two materials with low
water retention of 3 to 5% and 7 to 11% respectively. Hence,
spandex and polyester are the two materials with the best
moisture wicking ability.
Large amount of heat is being generated by the body during
jogging. Hence, the ability to transmit heat is considered.
Using the data of the thermal conductivity of materials as seen
in Table 1, cotton has the highest thermal conductivity of up to
0.5 J/m.s.k. The second highest are polyester and nylon which
have a thermal conductivity of 0.2 to 0.3 J/m.s.k. These three
materials are able to transfer heat away from the body better in
comparison with the rest.
For the additional feature of the proposed design, the ‘X
posture’ requires a fibre that has high elasticity to provide the
posture support. Based on table 1, spandex has the highest
elasticity as its elastic modulus is the lowest. Elastic modulus is
the measurement of an object’s tendency to be deformed
elastically (a temporary shape change that is self-reversing after

the force is removed)[29]. The unit cN/tex refers to
centiNewton/tex where tex is the mass of yarn in grams per
1000 metres length [30].
4.9. Materials Selection4.9.1. Materials for the Bulk of Jogging
Attire
Using the design concepts for the jogging attire for climate of
high temperature and relative humidity in Singapore, the
material chosen for the proposed jogging attire needs to possess
good moisture wicking ability to remove sweat, high moisture
vapour transportation to keep the jogger dry, high thermal
conductivity to transfer heat away from our body quickly and
lastly the ability to provide UV protection. All these properties
need to be available in the material to maximize a joggers’
comfort and to protect them.
After screening the materials using the above properties, the
material selected is a polyester-cotton blended yarn with a blend
of about 85% polyester and 15% cotton. The basis of the blend
will be elaborated in the subsequent paragraphs.
Polyester is a synthetic fibre which means that it has very linear
and rounded capillary which is the basic requirement for good
moisture wicking. It also has one of the lowest moisture
absorption of 0.8-1.0 % and water retention of 3-5 % when
compared to other synthetic fibres. This prevents the
accumulation of sweat in the capillaries and reduces swelling to
the minimum, and thus enhancing the moisture wicking ability.
In addition, polyester is able to provide UV protection as it
contains benzene rings, which allows it to absorb most of the
photons with wavelengths within the UVA and UVB region.
Lastly, it has one of the highest thermal conductivity values

among all the synthetic fibres of 0.2- 0.3 J/msk. Therefore,
attires made from polyester are able to conduct heat away faster
than any other synthetic fibres. However, the thermal
conductivity of polyester is not as good as natural fibres.
Furthermore, it is not air permeable. The properties required of
the fibre yarn can be improved by blending it with another
fibre, cotton.
Cotton is chosen to be blended as it has the highest thermal
conductivity amongst all the fibres selected with a value of up
to 0.5 J/msk. Coupled with high moisture absorption of up to
18% and water retention values of up to 50%, sweat produced
will be absorbed and trapped in the cotton fibres. This further
improves the thermal conductivity as water is a much better
conductor of heat than air trapped in fibres when the attire is
dry. In addition, cotton is air permeable which allows for good
moisture vapour transport. However, having too much cotton
blended disrupts the polyesters ability to wick moisture. Hence
the cotton blended is only kept at small amounts of about 15%.
Furthermore, a polyester-cotton blend not only retains the
coolness and lightness of the cotton fibre, but also retains the
strength, durability and wrinkle-resistance of polyester [31].
With cotton which absorbs the sweat away rapidly and polyester
which dries quickly, the comfort of joggers is maximised. The
benefits of the blended can also be seen in Figure 7.
Figure 7. Summary of Benefits of a Polyester-Cotton Blend [32]
The material used for pocket is the same as the material used
for the bulk jogging attire as the area inside and surround the
pocket have the same characteristic with the main part of the
body. In order to enhance its function, which is to keep small
stuffs, zipper is added to prevent stuff inside the pocket from
dropping.

4.9.2. Material for Armpit and Inner Thighs Area
The armpit and inner thighs are areas which receive the least
ventilation. In addition, the presence of apocrine glands makes
it even more susceptible to bacteria action creating body odour.
Therefore, a material with high air permeability has to be
selected to prevent accumulation of moisture vapour in these
areas and it must have anti-bacterial and fungi properties. Based
on these constraints, bamboo fibre is selected.
From Table 2 above, it is seen that bamboo fibre is air
permeable. This is because the cross-section of the fibre is
filled with various micro-gaps and micro-holes, leading to high
air permeability [23]. Its ability to absorb and evaporate sweat
rapidly enables the wearer to feel cool and comfortable as it
does not stick to the skin. Most importantly, the natural
antibacterial elements in bamboo fibre keep bacteria away from
bamboo fabrics, keeping odours at bay [23]. This unique
property is essential for the mentioned areas to prevent body
odour. Although it is slightly more expensive, the surface area
of the mentioned parts is small and cost can still be managed.
4.9.3. Material for X Posture
In order to create a force that is needed to maintain the posture
of joggers, the ‘X Posture’ on the back of the proposed attire
requires high elasticity and comfort at the same time. Therefore,
spandex which has the highest elasticity, with the lowest elastic
modulus of 0.3-0.7cN/tex among the above materials was
chosen as seen in Table 1. Spandex can be stretched repeatedly
and is able to recover to almost its original length and shape. It
is strong, durable, has high retractive force and can generally be
stretched to more than 500% without breaking [27]. Its high
elasticity is also the reason why it was chosen to be the material
of the top of the shorts as shown in the design.
5. Manufacturing Methods

5.1. Fibre Production 5.1.1. Polyester blended with cotton
fibres5.1.1.1. Polyester [28]
The polyester is produced by melt spinning. The polyester melt
is first extruded into water and cut into chips where the water
content is being removed to less than 0.004%. The chips are
then melted again and spun into long filament fibres by passing
them through the holes of the spinning nozzle as seen in Figure
8. Melt spinning of the fibres allows the production of highly
uniformed fibres which is essential for moisture wicking.
Figure 8. Melt spun process [33]5.1.1.2. Cotton [33]
The raw material used in manufacturing cotton is cotton plants.
After cotton plants are harvested using machines, the seeded
cotton is ginned using either a saw gin or a roller gin to clean
up the cotton by separating dirt and seed from the cotton as
shown in Figure 9. When cleaning is done, the cotton is sent to
gin stands where revolving circular pulls the filament fibre
through wire ribs to produce cotton bales.
Figure 9. Operation of the Cotton Gin
5.1.1.3. Blending of Polyester and Cotton
The long filament fibres polyester are first collected in large
bundles called tows and are mechanically cut into short fibres
termed as staple fibres [34]. About 85% polyester staple fibre is
then blended together with about 15% cotton based on mass
ratio using tablet weaving methods to produce the polyester-
cotton yarns [35].

5.1.2. Spandex Fibres [32]
Spandex fibres are made from segmented polyurethanes which
has high weight portions. The polyurethane chain is first formed
in a highly polar solvent. The solution is then pressed through
multi hole spinnerets using a gear pump through a thin layer
heat exchanger to a temperature of about 5 to 20K below the
boiling point of the solvent to produce fibers using the dry
spinning process.
5.1.3. Bamboo Fibres
There are two main types manufacturing process for bamboo
fibres, chemical and mechanical processes [36]. An experiment
was conducted using Phyllostachys edulis, one of bamboo
species, to compare the moisture wicking ability and the
mechanical properties between chemical and mechanical-
manufactured bamboo fibre [37]. The fabric specification for
both types was woven. The result is shown in the table 3 and 4.
Sample No.
Bamboo Species
Manufacturing Method
Fibre Specification
Average Breaking Force (CN)
Average Breaking Tenacity (CN/dtex)
1
Phyllostachys edulis
Chemical
1.56 dtex
17.7 + 2.8
11.4 + 1.8
2
Mechanical
5.88 dtex
146 + 20

24.9 + 3.64
Table 3. Fibre Breaking Force and Breaking Tenacity
Comparison [37]
Sample No.
Bamboo Species
Manufacturing Method
Fibre Specification
Average Absorption Time (s)
Total Time Needed to Dry (s)
(Dry time – Absorb time) / Absorb time
1
Chemical
Woven, Ne = 21
1.2
8196
8195
2
Mechanical
Woven, Ne = 21
163
452
451
Table 4. Moisture Wicking Properties of Bamboo Fabric [37]
Table 3 shows that mechanically-manufactured bamboo fibre
has strength which is twice as strong when compared to
chemically-manufactured bamboo. Table 4 provides the
calculation of the difference between the time of drying and
absorbing normalised by the absorption time, as shown in the
last column. It shows that the mechanically-manufactured
bamboo fibre has better moisture wicking ability since it has
lower value of 451, which means that the absorption and drying

process is faster in mechanically-manufactured bamboo fibre as
compared to chemically-manufactured bamboo fibre [37].
Hence, the mechanical process is chosen as it produces bamboo
fibres which are stronger and has better moisture wicking
ability compared to chemically-manufactured bamboo fibre.
In the mechanical processing, bamboo culms are first cut into
strips which are then boiled to dispose the inner fibres. Next,
the bamboo is broken into a soft mass by the addition of natural
enzymes. After which, the individual fibres are combed out and
eventually the fibres are spun into yarn [36].
Figure 10. The Mechanical Processing of Manufacturing
Bamboo Fibres [36]
5.2. Fabric Production Methods5.2.1. Warp knitting
The main fabric production method used is warp knitting as it
can be designed and made into many different constructions
through controlling the loop size and fibres used [33]. In
addition, knitting makes the fabric more air permeable as
compared to the weaving which is a very tight form of fabric
production as seen in Figure 11. Using a warp knitting machine,
the density of looping can also be controlled.
In the knitting process, the knitted fabric is produced using a
warp knitting machine which consists of 4 needles, bearded
needles, latch needle, compound needle and carbine needle. The
knitting process is done in such a way where the knitting loom
bed will produce a sequential and simultaneous movement of
the 4 needles looping the treads in the process and forming the
fabric with the looping patterns required [33].

Figure 11. Warp Knitted Fabric [33]
As seen in Figure 1, different areas of the body have different
sweating rates and areas with higher sweating rates will require
better moisture wicking ability. This can be done by increasing
the looping density which increases the number of fibres present
in the fabric. Hence, increasing the number of capillaries
responsible for moisture wicking. However, increasing the
looping density decreases the air permeability. Hence, a balance
needs to be maintained.
In the proposed attire, the looping density is varied according to
the sweating rates in Figure 1. The looping density at areas with
higher sweat rates will be higher than those with lower sweat
rates. This allows an increase in the number of moisture
wicking capillaries at required areas and maintains the overall
air permeability of the whole attire. However, only slight
variations can be made as the maintenance of the overall
uniformity of the fabric is also essential.
The spandex and bamboo fibres will be knitted into the fabric
individually and then sewn together with the polyester-cotton
blended fabric at required areas based on the design as shown in
Figures 5 and 6.
6. Final Design and Dimensions
The final designs are shown in Figure 13 and Figure 14. The
jogging attire will only come in dark colours as dark colours
enhance UV protection [17]. For a given fabric, brighter fibres
transmit more UV radiation than dull fibres. Hence, a protective
effect can be achieved by dyeing the attire with dark colours
such as navy or black.
As for the dimensions, the attire will come in different sizes,
but the attire is generally designed to be fitting to the body.
This is because if the ‘X Posture’ is not close to the body, the
effects of the pulling force that is on the shoulder cannot be felt

by the jogger, defeating the purpose of the additional feature.
Furthermore, when the attire is closer to the body, less air is
being trapped between the body and the attire, allowing more
heat to be conducted out of the body as air is a very poor
conductor of heat.
Figure 12. Final Design of the Top
Figure 13. Final Design of the Bottom7. Evaluations
The design of the proposed jogging attire aims to provide
sufficient comfort and protection that is catered to all joggers.
In this section, the proposed attire is evaluated based on 3
criteria: cost, comfort and protection.
7.1. Cost
As the proposed attire is catered to the general public, cost
becomes a very important concern. Sports attires are often more
costly as compared to other forms of attire and many people
will reconsider upon purchase. However, sports attires are very
important as they have functions specially catered to the
exercise needs and people might miss out on the benefits due to
the cost. By minimising the cost, the benefits can be made
available to everyone.
The design of our jogging attire is mostly based on the
manipulation of common fibres widely available in the market
and technology has been established to produce large amount of
such fibres at low cost. Furthermore, the manufacturing
processes employed are very simple as sophisticated
manufacturing translates to higher cost.
The use of more expensive fibres such as bamboo and spandex

might increase the cost slightly. However, by limiting the fibres
only to small areas required, the increase in cost is kept to the
minimum. The increase in cost due to the use of such fibres is
also justified as they are essential to the key features in the
proposed design. In general, the cost of the attire is kept to the
minimum, translating into lower cost.
7.2. Comfort
For a jogging attire, the most important need would be to
address the sensorial and thermal comfort that the jogger
requires while jogging, especially in a country like Singapore
where high temperature and high relative humidity are of
importance.
Through the use of polyester-cotton blended fibres, the
proposed attire is able to address the sensorial and thermal
comfort needs by keeping the wearer dry through removal of
moisture and keeping the wearer cool by increasing thermal
conductivity. The material selected has the best combination of
high thermal conductivity, moisture wicking and moisture
vapour transport amongst the shortlisted materials.
Also, the reduction of body odour through the use of bamboo
fibres further improves the sensorial comfort by reducing
unpleasant smell produced during jogging.
However, the proposed attire might lose out in terms of comfort
when compared to sports attire which makes use of performance
fabric made from advance technologies which are created to
maximise comfort at the expense of cost.
7.3. Protection

The protection against UV radiation helps to prevent skin
cancer and damage to the skin. For the proposed attire, the UV
protection provided is limited through the use of polyester
fibres and dyeing the attires in dark colours. The Ultraviolet
Protection Factor (UPF) is correlated to the fabric density and
thickness of the construction of the fibre [16]. With the increase
in thickness and fabric density of the proposed attire, more heat
is being trapped and moisture vapour transport is reduced within
the attire. Furthermore, the attire is knitted to improve the air
permeability, creating a large amount of pores which will allow
UV radiation to be transmitted. Hence, the fabric density and
thickness cannot be manipulated to increase UV protection.
The proposed attire is also designed based on the Singaporean
culture of dressing in short sleeve shirt and shorts. Therefore,
the limbs of the jogger will also be directly exposed to UV
radiation.
The method of adding optical brightening agents or fabric
whitening agents during the finishing operations as UV
absorbers are also not applied in the proposed attire as it is not
very helpful and would result in cost wastage. This is because
washing of the fabric leads to a decrease in UPF of the fabric
and reaches the level of the untreated fabric after 10 washes
[16].
Most of the methods available to increase UV protection
contribute to a decrease in comfort level. Since the proposed
attire focuses more on achieving required comfort, only the use
of polyester fibres and dyeing of fabrics are adopted for UV
protection.
8. Conclusion and Recommendations
The aim of this project is to come up with a design for jogging
attire for use in Singapore. Through the analysis of the climate
of Singapore and the bodily effects of jogging, the needs of a

person during jogging were established. The attire worn during
jogging has been proven to have an effect on the human body
functions and wearing inappropriate attire might be
uncomfortable for the jogger.
Four design concepts were established: good moisture wicking,
good moisture vapour transport and good thermal conductivity,
as well as the need for UV protection. Two additional features
were also included to enhance the jogging experience of the
user, through the need of maintaining body posture and reducing
body odour.
Materials were then selected based on their ability to fulfil
these design concepts and the additional features established.
The fibre of polyester-cotton blend was decided to be used as
the bulk of the material, while spandex was used in maintaining
the body posture and bamboo fibres were used to reduce body
odour.
Manufacturing methods were later explored with the aim to
further maximise the functions of the attire.
The proposed attire is largely able to function well based on
established theories in providing comfort for the mass public at
relatively low cost. However, UV protection provided is limited
and further research is essential in this field to fully enhance
the protection needs of a jogger.
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Journal of Textile and Apparel, Technology and Management,
Vol. 6, Issue 3.
DEHYDRATION DETECTOR FOR PROTECTIVE GEAR

Abstract
Recent studies have shown that many of the fatal cases of sport
activities are caused by dehydration and over-hydration, which
are due to the deficiency of water or
sodium in blood plasma. In South East Asian countries, the sun

is available throughout the year. Therefore, people stand a
higher chance from suffering heat injury during strenuous
exercises compared to those in the cooler regions.
The current methods for measuring dehydration and over-
hydration are complicated, inconvenient and unable to give
direct feedback during exercise. The objective of this project is
to innovate a new product that will measure the hydration level
of an individual. The main idea of the design is to apply the
concept of color change when the stability of colloidal gold
nanoparticles is affected by various sodium concentration levels
in the sweat.
The design will work in a way where three distinction colors
will be revealed on a wristband in different status of hydration
level. For the design, our project team is working hard on the
research about colloidal gold nanoparticle and its capping
agents and how to dope the gold nanoparticles onto a wristband,
which will hold a matrix of polymers absorbent material to
contain sweat.
Table of Contents
Abstractii
List of Figuresvi
1Introduction7
1.1Background7
1.2The Need8
1.3Objectives9

1.4Scope9
1.5Schematics of Final Products9
2Literature Review10
2.1Human Sweat10
2.2Conventional way of measuring hydration level11
2.2.1Body mass changes12
2.2.2Urinary Indices12
2.2.2.1Urine Specific Gravity12
2.2.2.2Urine osmolality12
2.2.2.3Urine Color13
2.2.2.4Urine Volume13
2.2.3Hematological indices13
2.2.4Salivary parameter13
2.2.5Sweat composition assessment14
2.3Hydration Sensor Integrated on Fabric14
2.4Gold nanoparticles15
2.5Preparation Methods for AuNPs as Sensors16
2.5.1Turkevich method16
2.5.1.1Citrate-capped Gold Nanoparticles16
2.5.1.2AuNPs stabilized by 3-thiophenacetic acid16
2.5.2Peptide Capping Ligands for Gold Nanoparticles17
2.5.3Brust-Schiffrin method18
2.5.4Seed-growth method18
3Comparison & Analysis19
3.1Wristband19

3.2Indicator20
3.3Superabsorbent pad21
3.4Absorbent pad with indicator22
3.5Top Cover23
3.6Temporary Bottom Cover25
4Final Design26
4.1Components of wristband26
4.2Indication of Hydration Levels27
4.2.1Sweat sodium concentration27
4.2.2Device Requirements27
4.2.3Sample synthesis of AuNP28
4.2.3.1Turkevich method28
4.2.3.2Theory28
4.2.3.3Addition of Na+ ions28
4.2.4Application of the concept28
4.3Problem encountered29
4.4Development of AuNPs for Sweat Na+ Concentration29
4.5Processing31
4.5.1Fabrication of AuNPs treated polypropylene31
4.5.2Producing components of the wristband31
4.6Assembling the components32
5Environmental Impact33
6Discussion34
6.1Advantages34
6.2Limitations35

6.3Recommendations35
7Conclusion35
References37
Appendix41
List of Tables
Table 21: Sweat sodium concentrations at different hydration
levels10
Table 31: Criteria for the wristband19
Table 32: Constraints for wristband19
Table 33: Objectives for wristband design13
Table 34: Criteria for the Indicator13
Table 35: Constraints for the Indicator14
Table 36: Criteria for Superabsorbent pad14
Table 37: Constraints for Superabsorbent pad15
Table 38: Objectives for Superabsorbent pad15
Table 39: Criteria for Absorbent pad with indicator15
Table 310: Screening for Absorbent pad with Indicator16
Table 311: Ranking for Absorbent pad with Indicator16
Table 312: Criteria for Top Cover17
Table 313: Screening for Top Cover17
Table 314: Ranking for Top Cover17
Table 315: Criteria for Temporary Bottom Cover18
Table 316: Screening for Temporary Bottom Cover18

Table 317: Objectives for Temporary Bottom Cover19
Table 51: The embodied energy and carbon footprint for each of
the components27
List of Figures
Figure 1: Schematic of final product10
Figure 2: Electrochemical sensor network (left) and control
printed circuit board (right)15
Figure 3: TEM images of AuNPs synthesized with different
concentration of TA, concentration decreasing from (A) to
(D)17
Figure 4: Final design of the Wristband26
Figure 5: Schematic of Transparent Indicator Pad20
Figure 6: Regional distribution of physiologically active eccrine
sweat glands, skin surface areas, gland counts and glandular
dimensions27
Figure 7: Color change upon addition of NaCl into stabilized
citrate capped gold solution28
Figure 8: Illustration of stabilized AuNP23
Figure 9: Ionic strength vs distance between colloidal gold
nanoparticles24
Figure 10: Carbon dioxide footprint for PVC and Silicone
production26
Figure 11: Embodied energy for PVC and Silicone26
Figure 12: Surface charge34
Figure 13: Effect of ionic strength35

IntroductionBackground
Water is a vital nutrient for life as it plays a crucial role in
regulating our body temperature, lubricating our joints and
transporting nutrients throughout the body. About 60% of our
body weight is made up of water and it is important to maintain
that balance. Staying hydrated is important for everyone and yet
people who are active in sport need to maintain the balance of
body fluid more. Therefore, adequate fluid intake is essential
for people who do sport before, during, and after exercise in
order to stay hydrated.
Dehydration is most commonly seen after exercise in which
heavy sweating has occurred. A side effect of sweating is the
loss of valuable fluids from the finite reservoir within the body,
the rate being related to exercise intensity, environment
conditions and so on. Dehydration of 1% to 2% of body weight
begins to compromise physiologic function and negatively
influences performance. Dehydration of greater than 3% of body
weight further disturbs physiologic function and increase an
athlete’s risk of developing an exertional heat illness (e.g. heat
cramps, heat exhaustion, heat stroke).
A major consequence of dehydration is a noted increase in core
temperature during physical activity. Core temperature raises
an additional 0.15 to 0.20 degrees Celsius for every 1 percent of
body weight lost due to sweating during activity. This thermal

strain also influences a greater cardiovascular strain. One
example of the changes in the cardiovascular system is a rise in
heart rate by an additional 3 to 5 beats per minute for every 1
percent of body weight lost. Further injury to the
musculoskeletal system is also present. These changes include
elevated muscle temperature and increased lactate levels.
Studies investigating the role of dehydration on muscle strength
have generally shown decrements in performance at 5 percent or
more hydration.
Fluids in the body are either inside the cell or outside of the
cell. When we become dehydrated, the fluid outside of the cells
decreases. Reductions in fluids cause nerve endings to be
squished together, overexcited and spontaneously discharge.
That spontaneous discharge is a muscle twitch, which can lead
to a muscle cramp. By maintaining proper hydration, you can
prevent dramatic shifts in fluids that contribute to abnormal
muscle contractions.
Although rare, over-hydration can occur during long bouts of
exercise when electrolytes lost through sweat are not replaced,
yet excessive amounts of water are consumed. Over-hydration
can lead to potentially dangerous imbalances of electrolytes,
including hyponatremia, a serious condition in which the
sodium level in the blood becomes too low. Hyponatremia can
be a problem for athletes who experience excessive sodium loss

through perspiration as part of prolonged exercise or heat
exposure, such as running a marathon.The Need
The effects of dehydration are greater in hot environments like
Singapore. Steinberg (2013) wrote that in dozens of cases in the
last thirty years athletes have died of dehydration. On the other
hand, drinking too much water can also be hazardous to your
health, leading to a condition called hyponatremia.
Hyponatremia means having low level sodium concentration in
your body fluids and it can even lead to fatal cases. Some
enthusiastic marathon participants sometimes take fluid more
than what their body have lost and encountered fatal cases.
According to an article of Biomechanics Fitness and
performance, the cases of over hydration are as serious as the
following.
· During the Chicago marathon in 1998, Kelly Barrett collapsed
and later died from hyponatremia.
· After the Houston marathon in 1999, 4 runners were
hospitalized with comas due to hyponatremia.
· During the Boston marathon in 2002, Cynthia Lucero died
from hyponatremia. In the same marathon, 13% of 488 runners
tested were hyponatremic.
· At the 2002 Marine Corps marathon in Washington, DC,
Hilary Bellamy died from hyponatremia.
· At the London marathon in 2007, David Rogers died from
hyponatremia.

It is difficult to know what your levels of hydration are. Thirst
can be a poor indicator of hydration because exercise blunts the
thirst mechanism. Body is already dehydrated when thirst
becomes detectable. Other indicators such as urine colors and
body weight lost during exercise are also not detectable while
exercising. The same principle applies for hyponatremia as
well. In addition, older people can have severe affects from
dehydration and hyponatremia. The thirst mechanism diminishes
as people age, and thus increases the risk for dehydration.
Maximal urinary concentrating ability also decreases as people
age and this can also increase risk for dehydration.
Reviewing the number of cases dehydrationand over hydration,
it is obvious that there is a need to indicate the hydration level
while we are exercising. A portable and user friendly device
that can tell a person’s hydration level will become handy for
athletes or people who are active in sports. As the effects of
dehydration and hyponatremia are more severe for older people,
the device will become even more essential for older adults in
hot and humid Singapore and other South East Asia
countries.Objectives
The purpose of this project is to produce a device that can
indicate the hydration level of a person by manipulating the
stability of the gold nanoparticles in various sodium
concentration levels. In this way, a person can check his

hydration level readily while exercising or doing sports. This in
turn will protect them from cramps; heat strokes and others
negative effects of dehydration and over hydration.Scope
Due to the limitation of time and resource, the dehydration level
of sweat at only forearm ventral will be measured. In addition,
the design mainly targets to marathon runners as dehydration
occurs more in the marathon runners as stated in background of
this report.
Indicator Pad
Adjustable Wristband
Schematics of Final Products
Figure 1: Schematic of final product
The schematic of the final design will be a wristband with an
indicator pad, which will change colour according to the
hydration level of the users. For more ergonomic design, the
wristband is made to be adjustable in order to fit the users
forearm ventral.Literature ReviewHuman Sweat
Dehydration is often accompanied by losing body’s mineral salt
or electrolyte balance. Human sweat mostly contains mainly
water. Besides, it also contains minerals, lactate and urea. The

mineral consists of sodium (0.9 gram/liter), potassium (0.2
gram/liter), calcium (0.015 gram/liter), magnesium (0.0013
gram/liter). Other elements such as zinc (0.4 milligrams/liter),
copper (0.3–0.8 milligram/liter), iron (1 milligram/liter),
chromium (0.1 milligram/liter), nickel (0.05 milligram/liter) and
lead (0.05 milligram/liter) are also present in human sweat. The
pH level of sweat typically ranges from 4.5 to 7.0. Losing of
slightly high concentration of sodium in sweat indicates one’s
under dehydration condition.
Nevertheless, the sodium concentration in plasma is finite in the
human body. Besides, sodium is considered a vital nutrient as it
is limitedly available. Athletes should consume sodium in order
to replace sodium losses over time. A long-term shortage of
sodium will be harmful to the body. On the other hand, over
consumption of sodium can lead to over hydration. This
normally happens during marathon races which have plenty of
stations that give out electrolytes to the runner. For instance,
the athlete replaces 100% of the fluid loss (1 L/h) with the
addition of 400 mg sodium/h. Across whole-body sweat rates
from 0.72 to 3.65 mg.cm-12.min-1, sodium losses of 26.5–49.7
mmol.L-1 could be expected.
Table 21: Sweat sodium concentrations at different hydration
levels
Condition
Na+ Concentration

Over hydrate
26.5 mM
Normal
40 mM
Dehydrate
47.9 mM
(Taylor, 2013)Conventional way of measuring hydration level
Common techniques used to monitor hydration status include
body mass changes, urinary and hematological indices, salivary
parameters, and total body water assessment. As dehydration
progresses, there are negative effects on heart rate, stroke
volume, cardiac output, fatigue, skin blood flow, plasma
volume, and rate of perceived exertion. Body mass changes and
total body water assessment need several procedures to go
through to get the accurate result while measurements of
salivary parameters and urinary properties are less reliable since
they vary with the food consumed.
With acute hypo hydration, urine demonstrates acute changes in
volume, color, specific gravity, osmolality, and conductance,
creating an opportunity to assess hydration status via relatively
noninvasive urinary indices.
A refractometer requires only a small volume of urine, is
temperature compensated, and can be used as a general guide to

an athlete’s hydration status. Furthermore, as refractometry is
portable, noninvasive, inexpensive, objective, and simple to use
by clinicians, it has become the preferred method for hydration
assessment by many investigators. Manual hand-held units and
digital refractometers are commercially available, with the
manual unit being both cheaper and more robust. Both
techniques provide almost identical results.
(Fiona, Gary, & Tanya, 2010)
The methods, which are currently available like what has been
stated above, are not very feasible for the project implications.
Preferred tool should be noninvasive, economical with minimal
consumable requirements, technically simple, portable, valid,
precise, and not influenced by factors unrelated to hydration
status. Therefore, further researches need to be done on more
reliable, accurate and fast methods.
There are several methods to assess the hydration level of the
human body. Body mass changes, urinary and hematological
indices, salivary parameters and total body water assessment.
Body mass changes
Rapid body mass changes are due to the gain or loss of body
water or the intake of food and fluids, as no other body
component is able to gain rapidly. Random variations of body
mass have been proven to be within ±1%. Therefore, the change

in excess of this amount is caused by the hydration level of the
body. Body mass measurement should be done at the same time
of the day such as in the morning before breakfast and training
with an empty bladder and bowel. In such condition, a baseline
body mass is measured and the value is advised to be use not
more than two weeks. To achieve the accuracy of the body mass
monitoring, the person should be wearing minimal clothing,
using the same scales throughout the assessment, consideration
of menstrual cycle in female and chronic energy imbalance.
Body mass assessment is a simple, noninvasive, inexpensive
method but it requires consistency and the person needs pay
close attention to the amount of water intake and urine output.
Urinary IndicesUrine Specific Gravity
This is the measurement of urinary density in relation with pure
water density. This can be used to determine the urine
osmolality and hence the hydration level. Common methods
used for measuring urine specific gravity are dipstick,
hydrometer and refractometer. However, urinary composition
also depends on the concentration of protein, urea and glucose.
Therefore, urine specific gravity becomes unreliable when there
are heavy molecules, which can cause increase in urine
osmolality despite of normal hydration level.Urine osmolality
Urine osmolality determined the total urine solute
concentration. This is a laboratory-based technique in which the

concentration is measured through a phenomenon called
freezing point depression in an osmometer. The method is
independent of big molecules such as protein, glucose and urea.
Therefore, it is considered the most accurate method to find out
the concentration of urine. Despite its accuracy, the method is
not useful as it is not portable.Urine Color
Using an eight-color strip, the hydration level is obtained as a
reasonable index. The strip consists of a color spectrum ranging
from pale yellow to greenish brown. This method is a rather
simple, expensive and portable method to determine the
hydration status. Urine color is assessed in a well-lit room by
comparing to the color chart with a white-colored background.
However, certain food and drugs ingested can affected the color
of the urine regardless of the hydration level.Urine Volume
Urine Volume monitoring is another technique which can be
used by the athletes to independently measure their hydration
level. Athletes are advised to take note of the fluid intake and
frequency of urination. However, urine volume is quite
inconvenient to collect and assess. It also reflects the fluid
intake and provides too little information about hydration
status.
Hematological indices
This is a blood-borne measurement to determine the plasma
osmolality by analyzing concentration changes in hemoglobin

and hemocrit. To obtain accurate result, the standardized
posture must be maintained for 15-20 min. This method is
capable of detecting the body water deficit of 1-5%. Despite all
the advantage, taking blood sample in this field is impractical.
This can introduce risk of getting infection, vein damage and
bring discomfort to the athletes. In addition, it needs qualified
specialist and complex laboratory equipment. Therefore, such
test is suitable only when reliability, precision and accurate
results are needed.
Salivary parameter
Salivary parameter is a viable method to assess hydration level,
as it is noninvasive, simple and inexpensive. Salivary plasma
osmolality has a strong correlation with the body mass loss. But
the changes in saliva index are less sensitive to hydration level
compared to plasma osmolality and body mass assessment. In
addition, the temporary effect of food consumed can bring
minus point to this method as well.
Sweat composition assessment
Sodium and chloride are the primary components in the sweat.
Other mineral comprises calcium, magnesium, and potassium in
small quantity. During endurance, exercise, the imbalance in
water and sodium concentration can lead to hyponatremia and
hypernatremia. There are two ways to assess sweat composition.

They are whole body wash down and regional skin surface
collection. The former one seems to be more reliable while the
latter is more viable to use because of its simplicity. It is almost
impossible to collect all the sweat from the whole body during
exercise. However, the average sweat concentration can be
collected with carefully selection of skin area such as forearm,
which represents about the average concentration value of
whole body.Hydration Sensor Integrated on Fabric
The electrochemical sensor has host molecules in conducting
polymer to selectively measure sodium ions concentration in the
sweat. This device is made of fabric network deposited with
organic-metallic fluid and patterned copper and gold ions
electrodes as shown in figure 2. These networks act as
electrodes, called ionic selective electrodes, for measuring the
electrochemical reaction by applying a voltage of 1.2V across
them. The sensor network is electrically connected to a portable
electronic board as shown in figure. This electronic circuit
board is equipped with analog parts, control block (with
microprocessor), and connection to electrochemical electrodes.
The device is able to measure a sodium concentration sensitivity
of 2mV/mM from 1.25-62.5mM. The paper has not mentioned
how user will be able to realize the hydration levels. The
complexity and bulkiness of electronic circuit becomes a barrier
for its commercial value.
Figure 2: Electrochemical sensor network (left) and control

printed circuit board (right)
Gold nanoparticles
Determination of analytes using aggregation of gold
nanoparticles has received much attention in recent years. It is
because determination of analytes using aggregation of gold
nanoparticles is much simpler if compared to some other
processes and in some cases using only own eyes can even be
the way to determine because the color change from red to blue
or vice versa is easily detectable. The two major groups of
analytes that could be determined from this process are
inorganic ions and biologically analytes such as amino acids,
peptides and DNA fragments.
Gold nanoparticles are produced by using citrate to reduce gold
salt (HAuCl4) at a temperature about 100ᵒC. The reaction is the
reduction process of Au3+ to Au0 and can be described by the
following equation.
Citrate + HAuCl4 Au0 + by-product
A certain amount of energy is required and thus the reaction
does not occur at room temperature. When HAuCl4 solution is
boiling the addition of citrate will induce instant formation of
gold atoms in the solution. Moreover, the gold atoms
concentration will rapidly increase until a super-saturation stage
is reached. Thus, a nucleation process will occur until the
aggregation of the gold atoms. The remaining gold atoms will
bind to the nuclei which gradually grow towards the final gold

particles.
Preparation Methods for AuNPs as Sensors
Turkevich methodCitrate-capped Gold Nanoparticles
Citrate acts as both stabilizing and reducing agent. Citrate
stabilized AuNPs has been considered to be the most popular
ones. After the HAuCl4 solution is boiled, the trisodium citrate
dihydrate is then added quickly by stirring it vigorously. The
wine-red colloidal suspension will be obtained after a few
minutes, and the average size of AuNP is approximately 20nm.
Furthermore, it was investigated that there is a broad size range
of AuNPs (from 15 to 150nm) was obtained by manipulating the
ratio of trisodium citrate to Au. Nevertheless, particles larger
than 20nm were always polydispersed.
This mechanism of AuNPs formation has been examined further
in order to improve the Turkevich Frens method. Kimling et al.
found that AuNPs of smaller sizes will be stabilized under high
concentration of citrate more rapidly. However, a low
concentration of citrate brings instability instead. It leads to
large-size AuNPs formation and even causing the aggregation of
AuNPs. Citrate-stabilized AuNPs were also used for further
usage such as intermediates in further preparations or
functionalizations for ligand substitution reaction and seed-
growth-mediated syntheses.AuNPs stabilized by 3-
thiophenacetic acid

Amongst the increasingly interested field, Nano world of
metals, gold has the most attention. Gold nanoparticles have
shown big contrast in chemical and physical properties from the
bulk since its introduction by Turkevich in 1951. Researches in
this field have expanded rapidly and many methods are now
available to improve the quality and control the physical
properties of gold nanoparticles. By using thiols, polymers,
surfactants and ligands as capping agents not only can control
the particle size, shape and prevent agglomeration, but also can
equip surface of gold nanoparticles with functional groups.
3-thiophenacetic acid acts as a reducing agent for preparation of
gold nanoparticles from HAuCl4. This research has proven that
different concentration of TA can affect the shape and size of
gold nanoparticles. With high concentration of TA, number of
small spherical AuNP is increased and the ionic solution is
more isotropic. When the concentration is eventually decreased,
more polygonal particles are formed as shown in the TEM
images in figure.
Figure 3: TEM images of AuNPs synthesized with different
concentration of TA, concentration decreasing from (A) to (D)
Peptide Capping Ligands for Gold Nanoparticles
The stabilities depend on these peptide ligands in the aspect of
their length, hydrophobicity and charge and in some cases
resulted in further improved stability compared with CALNN,

yielding detailed design criteria for peptide capping ligands.
The presence of charged amino acids substituted into the
hydrophobic core, resulting in peptide sequences that generally
provide poor protection against aggregation. For instances,
CDDNN-, CKLNN-, and CDLNN-capped nanoparticles will
aggregate at relatively low NaCl concentration, although the
presence of a negative charge in the third position (CADNN)
provide better stability than at the second position. The
concentration of NaCl that induces aggregation of the peptide-
capped nanoparticles will be reduced further by introducing a
second terminal negative charge (CALND, CALLD, CALSD,
CALKD).
The stability of gold nanoparticles against NaCl-induced
aggregation is strongly dependent on the amino acid sequence.
The presence of charged amino acids in the peptide core
decreases its stability against NaCl-induced aggregation.
Brust-Schiffrin method
Brust-Schiffrin method uses alkylthiols of different chain
lengths to stabilize AuNPs. The two-phase Brust-Schiffrin
method was the method which able to prepare the thiolate-
stabilized AuNPs. Its high impact is due to relative high thermal
and air stability of the AuNPs prepared. Besides, it has repeated
isolation and re-dissolution without aggregation or
decomposition. This method is able to control of the small size

(less than 5nm) with narrow dispersity and relatively easily
functionalization and modiﬁcation by ligand substitution.
The AuNPs are stabilized by relatively strong Au-Sbonds, and
their diameters are in the 2–5nm range. Fast NaBH4 addition
and cooled solutions will be producing smaller, more
monodispersed AuNPs.
The reducing agent used in Brust-Schiffrin method has larger
strength than the citrate used in the Turkevich method.
Therefore, the size of the AuNPs synthesized using the citrate
reductant in Turkevich method is much larger than that of
Brust-Schiffrin method using the NaBH4 reductant.
Other capping agents for this method are polymers, dendrimers
(surfactants and reverse micelles)
Seed-growth method
This method is another popular technique for AuNP synthesis
that has been used. The particles size is enlarged by carrying
out this method step by step. It will be easier to control over the
sizes and shapes of AuNPs formed. Thus, this procedure is
widely used in the size-and shape-controlled AuNPs syntheses.
This method produces AuNPs in different shape. E.g. Spherical
or quasi-spherical AuNPs, gold nanorods (AuNPs).Comparison
& AnalysisWristband
The function of the wristband is to mount the indicator pad onto
forearm. Therefore, the wristband must be adjustable in order to

fit different users. On the other hand, the wristband will mainly
be used by runners and therefore it must be water resistant and
able to function at human body temperature. It is also required
to be flexible, robust and light-weight at the same time so that it
will be ergonomic and user friendly. Therefore, these statements
can be translated into the constraints and objectives, which are
listed below:
Table 31: Criteria for the wristband
FUNCTIONS
Hold the indicator pad
CONSTRAINTS
· Flexible
· Water resistant
· Operating temperature 35ᵒC - 40ᵒC
· Robust
· Light weight
OBJECTIVES
· Adjustable Length
· Minimize cost
FREE VARIABLES
Choice of materials

Screening through the constraints
Table 32: Constraints for wristband
MATERIALS
Silicone Elastomers
Polyvinylchloride
Polyurethane
Flexible
Yes
Yes
Yes
Water Resistant
Yes
Yes
Yes
Operating Temperature
-60.67oC to 256.67oC
-98.25oC to 65oC
-48.16oC to 76.67oC
Robust (Fracture Toughness)
0.26 MPa.sqrt1/2

3.3 MPa.sqrt1/2
0.3 MPa. sqrt1/2
Density
1.55 g/cm-3
1.42 g/cm-3
1.13 g/cm-3
The above table clearly shows that those three materials fulfill
all the constraints. Thus, the ranking will of the materials will
be based on the objectives.
Ranking through the Objectives
Table 33: Objectives for wristband design
MATERIALS
Silicone
Polyvinylchloride
Polyurethane
Adjustable length
Yes
Yes
Yes
Cost
11.6 USD/kg
1.49 USD/kg
5.88 USD/kg
According to the above table, the first objective, which is

“Adjustable length” can be obtained by altering the design of
the wristband. Therefore, the ranking will be based on cost as
minimizing cost is the second objective.
All the data are obtained from CES Edupack software. Polyvinyl
chloride, the cheapest among three materials, is chosen as it
fulfills the second objective which is “Minimizing
cost”.Indicator
Table 34: Criteria for the Indicator
FUNCTION
Change colour when ions concentration change
CONSTRAINTS
· Able to change colour
· Respond to human sweat
· Non-toxic
OBJECTIVES
· Responsive
· Minimize cost
FREE VARIABLE
Choice of Technology

The ability to reflect the changes of ion concentration by
changing colour is crucial for deciding which technology to be
used for indicators.
Table 35: Constraints for the Indicator
MATERIALS
Colloidal Technology
(Gold nanoparticles)
pH Technology
(Litmus paper)
Change Colour
Yes
Yes
Response to hydration level
Yes
No
Non-toxic
Yes
Yes
The above table clearly indicates that only colloidal technology
using gold nanoparticles is able to pass the required constraints
as it will response to ions changed in human sweat and hence to

hydration level.Superabsorbent pad
Table 36: Criteria for Superabsorbent pad
FUNCTION
Absorb and store sweat
CONSTRAINTS
· High absorbency
· Non-toxic
OBJECTIVES
· Minimize cost
FREE VARIABLES
Choice of material
Table 37: Constraints for Superabsorbent pad
MATERIALS
Sodium Polyacrylate
Potassium Polyacrylate

Absorbency
800 times its weight
200-1000 times its weight
Non-toxic
Yes
Yes
After screening through both constrains both Sodium
Polyacrylate and Potassium Polyacrylate, it is found that both
candidates are able to meet the constraints. Therefore, final
decision should be based on the objective.
Ranking through the objectives
Table 38: Objectives for Superabsorbent pad
MATERIALS
Sodium Polyacrylate
Potassium Polyacrylate
Price
10 USD/kg
18 USD/kg
Ranking through the objective which is minimizing cost, sodium

polyacrylate is chosen due to cheaper price compared to
potassium polyacrylate. During our research, it is also found
that sodium polyarcylate is widely used in baby diapers and
feminine hygiene products whereas potassium polyarcylate is
mostly used for fertilizers.Absorbent pad with indicator
Table 39: Criteria for Absorbent pad with indicator
FUNCTION
Absorb sweat and accommodate indicator
CONSTRAINTS
· Lower absorbency compared to super absorbent pad
· Good durability when in contact with sodium(weak alkalis)
OBJECTIVES
· Minimize cost
· Material compatibility
FREE VARIABLES
Choice of materials
Table 310: Screening for Absorbent pad with Indicator
MATERIALS

Polyester(cotton)
Polypropylene
Polychloroprene(sponge)
Durability with weak alkalis
Acceptable
Excellent
Excellent
Water absorption @24hrs
1.25%
2.2%
0.7%
Screening through the constraints, it is observed that all the
materials are durable and have low water absorption rate.
Therefore, ranking needs to be done by objectives.
Table 311: Ranking for Absorbent pad with Indicator
MATERIALS
Polyester(cotton)
Polypropylene
Polychloroprene(sponge)
Materials Compatibility
Excellent

Excellent
Poor
Price
10.97 USD/kg
1 USD/kg
6.68 USD/kg
http://www.skydrol.com/pages/materials_chart.asp
Ranking through the objectives, it is found that
polycholoroprene has very poor materials compatibility. On the
other hand, polyester and polypropylene have excellent
materials compatibility. Nevertheless, polypropylene is chosen
as it fulfills both of the objectives which are minimizing cost
and materials compatibility.Top Cover
Table 312: Criteria for Top Cover
FUNCTION
Protect the indicator pad and reduce evaporation
CONSTRAINTS
· Transparent
· Able to react with epoxy(glue)
OBJECTIVES

· Good in blocking UV radiation
· Minimize cost
FREE VARIABLES
Choice of materials
Table 313: Screening for Top Cover
MATERIALS
Polycarbonate
Polyethylene terephthalate
Polystyrene
Transparency
Transparent
Transparent
Transparent
React with Epoxy
Yes
Yes
Yes
Screening through the constraints, it is observed that all the
materials can meet the constraints. Therefore, it is needed to
rank the materials through the objectives.

Table 314: Ranking for Top Cover
MATERIALS
Polycarbonate
Polyethylene terephthalate
Polystyrene
Good in blocking UV radiation
Fair
Good
Fair
Cost
4.34 USD/kg
2.8 USD/kg
2.27 USD/kg
From the above table, polyethylene terephthalate is better in
blocking UV radiation compared to the other two. However, it is
not a high prerequisite to have so much high in both
transparency and blocking UV radiation. Since, polystyrene is
cheaper than polyethylene terephthalate; it is more rational to
choose polystyrene to save the overall production
cost.Temporary Bottom Cover
Table 315: Criteria for Temporary Bottom Cover
FUNCTION

Protect the indicator pad from contamination
CONSTRAINTS
· Prevent particles from passing through
OBJECTIVES
· Minimize thickness
· Minimize cost
FREE VARIABLES
Choice of materials
Screening through the objectives
Table 316: Screening for Temporary Bottom Cover
MATERIALS
High Density Polyethylene
Polyurethane
Polycarbonate
Permeability
59.6 cm3.mm.m-2.day-1.atm-1
70.75 cm3.mm.m-2.day-1.atm-1
98.3 cm3.mm.m-2.day-1.atm-1
Screening through the objectives, it can be seen that all the

materials can prevent particles such as dust from passing
through. There, it is again needed to rank the materials through
the objective.
Table 317: Objectives for Temporary Bottom Cover
MATERIALS
High Density Polyethylene
Polyurethane
Polycarbonate
Price
1.86 USD/kg
5.89 USD/kg
4.34 USD/kg
Density
0.96 g/cm3
1.10 g/cm3
1.20 g/cm3
Ranking through the objectives, it is observed that the densities
of the materials are close enough and thus the only objective

that will help us to choose is the pricing. High Density
polyethylene, being the lowest price is therefore chosen as the
temporary bottom cover.Final Design
After considering different aspects of the components, the final
design is to be made into a colour changing wristband. This
section will illustrate the details of the wristband and the
technology used to produce it.Components of wristband
3cm
2cm
30 cm
1.5cm
Figure 4: Final design of the Wristband
The final design of the wristband will have the following
dimensions.
· Length of wristband = 30cm
· Width of wristband = 1.5cm
· The transparent indicator pad = 3 cm x 2cm
The transparent indicator pad consists of transparent

polycarbonate, nonwoven polyester with AuNPs, pulp with
sodium polyacrylate (superabsorbent) and temporary
polystyrene sheet. The diagram below shows the schematic of
the transparent indicator pad.
Transparent polystyrene
Nonwoven polypropylene with AuNPs
Nonwoven polypropylene with AuNPs
Pulp + Sodium Polyacrylate
Temporary polyethylene sheet (Optional)
Figure 5: Schematic of Transparent Indicator Pad
Indication of Hydration Levels
Sweat sodium concentration
Sweat rate is highly depends on the density of eccrine glands.
These glands are found within the first 3 mm of the skin and
their density range from 37 to 518 glands.cm-2. Forearm have
been chosen for wearing the device as it has the average gland

density of 104 glands.cm-2 and hence, it represents the average
sweat rate of the whole body.
Figure 6: Regional distribution of physiologically active eccrine
sweat glands, skin surface areas, gland counts and glandular
dimensions
During exercise, sweat sodium ions concentration will vary
from 26.5 to 49.7 mM. The average value for the normal
condition is 40mM according to Jonathan Toker, 2009.
Therefore, 26.5 mM corresponds as one extreme condition for
over hydration, where the sodium concentration of the body hit
the dangerous level leading to hyponatremia. On the other hand,
49.7 mM represents the dehydration extreme, hypernatremia.
Device Requirements
Colloidal property of gold nanoparticles (AuNP) is the main
concept of the device. The citrate capped gold particles will
aggregate and show color change upon adding different
concentration of sodium ions. The idea has been applied in the
device. When the sweat gets absorbed into the materials, the
stability of the nanoparticles will be affected.
Sample synthesis of AuNPTurkevich method
This method was developed in 1951 and it is the most
established way to synthesize gold nanoparticles. Following this
method, several methods were developed with different types of

capping. In Turkevich method, sodium citrate acts as both
stabilizing and reducing agent.Theory
AuNPs are produced by reducing gold salt (HAuCl4) with
sodium citrate at a temperature of ~ 100˚C. The solution will be
stabilized with 15 nm to 150 nm of AuNPs equally dispersed
throughout the solution. The particles are usually described as
colloids and they show Tyndall effect of light scattering.
Therefore, upon synthesis, the sizes of the colloids are too small
when compared to the wavelength of the visible light (400-
800nm). Hence, the solution is observed as colorless.Addition
of Na+ ions
In the presence of positive salt ions, Na+ (> 0.1M) in this case,
the colloid will start to aggregate and the solution color will be
changed from colorless all the way to dark grey. The step of
color change spectrum is shown in Figure 7.
Figure 7: Color change upon addition of NaCl into stabilized
citrate capped gold solution
Original
Three drops of NaCl solution
One drop of NaCl solution
Application of the concept
The color change of the gold nanoparticles in visible range is
utilized to identify the hydration level of the athlete. Under

normal condition, the start condition will be yellowish color. As
the exercise proceed, the change in color will correspond the
hydration level of the athlete. For example, while an athlete is
exercise without any water compensation, the perspiration will
eventually lead to dehydration (hypernatremia) in which the
concentration of the sweat will be getting higher and hit the
extreme condition of 49.7mM (red wine). On the other hand,
when the athlete is well aware of dehydration treat and intakes
too much water while exercising. In this case, the concentration
of Na+ in the body will greatly reduced and leads to
overhydration (hyponatremia). So, the device will respond as
the other extreme case, becoming colorless at about
26.5mM.Problem encountered
The stability of AuNPs is only altered at above 0.1M of NaCl
concentration. However, the concentration of Na+ ions in the
human sweat concentration is way too low when compared to
the laboratory trigger. Therefore, the stability of colloidal gold
nanoparticle will have to be developed in a way that the particle
will be less stable and perform color change at low Na+
concentration level.Development of AuNPs for Sweat Na+
Concentration
In citrate capped gold solution, the gold nanoparticles are
surrounded by negatively charged citrate ions as shown in
Figure 8. Hence, gold-citrate interaction leads to a protection
layer rich in negative charges, which create repulsive forces

between gold nanoparticles, in turn, preventing the aggregation
the nanoparticles. Upon adding Na+ ions, those ions will react
with the negative citrate ion. So, the protection layer is
destroyed and the AuNPs will start to aggregate.
Figure 8: Illustration of stabilized AuNP
For the project application, the stability of the gold
nanoparticles has to be tuned to be stable at 40 mM of Na+
concentration with yellow color. This is where the concept of
DLVO theory comes into importance. The theory states that the
stability of the colloids in the ions solution is achieved by the
balance between the electrostatic repulsion force and Van der
Waals attraction force. Van der Waals force is determined by
the size of the colloid and the electrostatic repulsion depends on
the amount of citrate ions on the surface of the gold
nanoparticles. According to the previous research, when the
zeta potential of the colloid is above 20mV of magnitude, the
particles are stable. Therefore, the objective is to tune the
stabilization of zeta potential. The one which starts to aggregate
at 0.1 M of sodium chloride has the size of 20 nm and zeta
potential of 20 mV. Researches has proven that size, shape and
capped ion concentration adjustments are done by varying
reaction temperature, pressure, and concentration ratio of the

gold salt and capping agent.
The shaded area will be the project scope of nanoparticles
reaction region. Point A is the initial position for AuNP. The
color of the solution will be yellow and the citrate shell of two
AuNPs will be slightly overlapping. During dehydration, the
position on the graph will move to point B where the solution
becomes more overlapped and color changes to red wine. On the
other hand, when overhydration condition, the particles will
split far apart again which is Point C.
Figure 9: Ionic strength vs distance between colloidal gold
nanoparticles
A = normal condition
B = dehydration condition
C= over hydrationProcessing
Fabrication of AuNPs treated polypropylene
AuNPs were synthesized by using sodium citrate and aqueous
HAuCl4 solution. Non-woven polypropylene sheets were dipped
into container containing AuNPs until the AuNPs are diffused
homogenously into polypropylene sheet. After dipping, the
polypropylene sheets were rinsed thoroughly with distilled
water to remove any loosely bound AuNPs, and the papers were
air-dried and stored at 50% relative humidity and 23 ᵒC.

Producing components of the wristband
Absorbent pad is produced on a movable conveyor belt that
crossed through a forming chamber. At different point of the
chamber, there will be pressurized nozzles that spray either
polymer particles or fibrous materials onto the conveyor
surface. The conveyor is holed so while the material is sprayed
onto the belt, a vacuum is applied from below so the fibers are
pulled down to form a flat pad. The mixture of polymer and
fibrous material is important since it controls the consistency of
the pad. Multiple spray dispensers are applied to form several
layers of polymers and fibers. As the vacuum pulled down the
fibers to the bottom pad, polymer is added to form a layer of
combined polymer and fiber, and then more fibers will be added
on top. Moreover, PVC wristbands are produced using injection
molding. On the other hand, transparent polycarbonate sheets
are produced by thermoforming process. Polystyrene sheets are
produced by expandable blow molding.Assembling the
components
The internal pad (the pad containing AuNPs) is proposed
process in continuous process for example conveyor belt.
1. The pre-produced absorbent pad which has the dimension of
1cm x 2cm are put onto conveyer belt of another machine once
they have been produced.

Design of jogging sportswear for use in tropical countries.docx

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