This document discusses the biomedical effects of underwear. It covers three key areas: 1) The insulation of underwear is less important than other clothing since it is closest to the skin, but its tactile properties and moisture handling are more significant. 2) Tactility refers to the sense of touch, which underwear impacts through properties like smoothness, softness, and moisture uptake. 3) The ideal underwear would wick sweat away rapidly, absorb large amounts without feeling wet, and dry quickly while being lightweight and comfortable.

1. T. M. Ashikur
Rahman
Id: 191-097-801
Section- TE-02

3.  Biomedical is the field of study that focuses on the areas of biology and
chemistry that are relevant to healthcare. The discipline is very wide-
ranging, and there are three general areas of specialty –
 Life sciences
 Physiological sciences
 Bioengineering
 Undergarments or underwear are items of clothing worn beneath outer
clothes, usually in direct contact with the skin, although they may comprise
more than a single layer.

4.  Soft
 High wicking characteristics
 Rapidly absorb large amounts of sweat
 Dry rapidly
 Non-compressible
 Light weight

5. The biomedical effects of underwear are relatively unique among clothing items.
While its insulation tends to be of less importance than that of most clothing
items, its tactile properties, and the way in which it handles moisture, are of much
greater concern since underwear is in direct contact with the skin.
 Warmth
 Tactility
 Moisture Handling

6. The warmth of any clothing item is directly related to its thickness. The insulation of
underwear is seldom a major consideration in thermal comfort, since it lies within an
already trapped still-air layer between the skin and the outerwear. Heat transport processes
by using a lattice that represents the Penne's bioheat equation in perfused tissues, and
diffusion in nonperfused regions. The three layer skin model has a nonperfused viable
epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is
constant or temperature-dependent. Two cases are considered:
 surface contact heating and
 spatially distributed heating
This is relevant to the prediction of the transient and steady state temperature rise for
different methods of power deposition within the skin.

7. Surface contact heating
 Contact heating is used in
transcutaneous blood gas monitoring,
in which oxygen is transported out of
the vasodilated capillary bed to a
surface mounted oxygen
sensor. Typically the ambient air
temperature even with undergarments
insulation causes the skin surface
temperature to be significantly cooler
than body core temperature. The basic
idea is that contact surface heating
results in heat transport into the body,
such that the outer portion of the
dermis experiences a significant
increase in perfusion.
Spatially distributed
heating
 Spatially distributed heating of skin
and deeper tissue by electromagnetic
fields and ultrasound is also of
established interest. Microwave
electromagnetic radiation is incident on
tissue under a variety of exposure
conditions. In this case, the penetration
depth is approximately 3 mm so that
most of the power is deposited within
the outer region of the skin. By
delivering thermal energy, the tissue is
stimulated to increase the blood flow by
thermoregulation in order to remove
the excess heat.

8. Tactility is a word that is used to describe the sense of touch; the transfer of certain information
registered by the skin. With the tactile sense we get information of things such as temperature,
shape or surface properties – things that we feel when we touch something. The skin is made
out of layers. In these layers there are sensory receptors of different types as well as nerves.
When focusing on the tactile sense there are four types of mechanoreceptors to consider. These
measure the forces of pushing and pulling in different ways and are named; Meissner´s
corpuscula, Merkel disk receptors, Pacinian corpuscula and Ruffini endings.
 The contact characteristics of undergarments have not been well worked out, although a
significant percentage of the population has a true, genetically based, allergic dermatitis
when wearing wool undergarments. In even more cases, the discomfort produced by
undergarments contact is an irritant dermatitis, rather than an immunological (i.e.,
allergic) dermatitis.
 Clearly smoothness as opposed to roughness, and silkiness as opposed to scratchy, are
relevant properties for undergarments tactile comfort, as probably is softness as opposed to
hardness. However, there appear to be wide differences in individual sensitivities and also
these tactile sensations change dramatically with moisture uptake of the fabrics in contact
with the skin.

9. The sweat handling properties of underwear are probably far more important for comfort
than their contact sensations. Individuals can characterize the actual water content of a
fabric in contact with the skin with good repeatability.
 Wicking
 Water uptake
 Drying
These projections as to the interaction between the water handling characteristics of
underwear fabrics, as measured by a variety of wicking, water absorption and drying tests,
all require further confirmation against human perceptions. Nevertheless, it appears that
the ideal underwear would be "soft", have extremely high wicking characteristics, should be
able to absorb sweat in an amount of 400% of its dry weight or more in a minute or less,
and should dry extremely rapidly despite being as thick, non-compressible and lightweight
as possibly.