Data logger

1. INTRODUCTION:
What Is Data Logger?
A data logger is an electronic device that is used to store data over time, commonly known as data
logging. This includes many data acquisition devices such as plug-in boards or serial
communication systems which use a computer as a real time data recording system. Nowadays,
wireless transmitters are also capable of turning a regular smart phone (or tablets) into a mobile
data logger.
Data-logging interfaces connect to computers and can have sensors plugged into them.
They convert the readings which they derive from the sensors into data which the computer can
use. They convert continuous variable signals from the sensors to numbers using a circuit called
an analogue-to-digital converter. These numbers are converted into real values and displayed by a
computer programme. Some data-logging interfaces - called dataloggers - have their own memory
and power supply and can record data without an attached computer.
A data logging device is often battery powered for use where no electrical supply exists,
data loggers accept one or more sensor inputs, sampling and saving the data at a predetermined
frequency. This could be as fast as several hundred per second or as slow as several hundred per
day (and faster and slower data loggers are available).
Data loggers are used wherever there is some advantage in recording conditions over a
period of time. Applications range from obtaining a record of wind speed to tracking temperature
in refrigerated storage containers, to monitoring flow rate at a remote pumping station. At the end
of the acquisition period the data logger is retrieved and the data downloaded into a PC for analysis.
Alternatively, data loggers are available that will wirelessly transmit measurement results to a PC
with a data logging software installed.
Data loggers benefit users in two ways. They avoid the time and expense of sending
someone to take measurements in a remote location, and they enable much higher data density
than is achievable through manual recording, providing higher quality data. A data logger provides
the ability to take measurements in any location, even during transit, without human intervention.
Furthermore, measurements can be closely spaced to capture transient events or far apart to
maximize recording duration. Another advantage of data loggers is that the data can then be easily

2. transferred to a PC for analysis and formatting. This significantly reduces the work required to
make measurements while allowing for increased data density when needed.
Many different types of data loggers are available. They range from single channel devices
with the sensor incorporated, to multi-channel data loggers capable of acquiring from diverse
sensors for extended periods. Data logging software provides the ability to configure acquisition
parameters and format data outputs.
Usually in our campus, the available and usually used by science students in laboratory are
pH meter, digital thermometer, dissolved oxygen meter, pressure sensor and so on. This actually
can attract students to more get involved in laboratory sessions. Hence, the lesion learn session
will be more interactive and easy to understand.
OSMOTIC PRESSURE
Osmotic pressure is the minimum pressure which needs to be applied to a solution to
prevent the inward flow of water across a semipermeable membrane. It is also defined as the
measure of the tendency of a solution to take in water by osmosis. Potential osmotic pressure is
the maximum osmotic pressure that could develop in a solution if it were separated from distilled
water by a selectively permeable membrane. The phenomenon of osmosis arises from the
propensity of a pure solvent to move through a semi-permeable membrane and into a solution
containing a solute to which the membrane is impermeable. This process is of vital importance in
biology as the cell's membrane is semipermeable.
Osmotic pressure through a semipermeable membrane means separating two solutions with
different concentrations of solute. It is the natural force of minerals dissolved in water moving
across a semi-permeable membrane into another body of water containing less minerals in an effort
to equalise. This differences between the two sides is called pressure. This natural force is used to
good effect in producing clean and mineral-less water via a process called RO or known as Reverse
Osmosis.
Osmotic pressure also important factor in affecting cells. Osmoregulation is
the homeostasis mechanism of an organism to reach balance in osmotic pressure. Hypertonicity is

3. the presence of a solution that causes cells to shrink. Hypotonicity is the presence of a solution that
causes cells to swell. Isotonicity is the presence of a solution that produces no change in cell
volume. When a biological cell is in a hypotonic environment, the cell interior accumulates water,
water flows across the cell membrane into the cell, causing it to expand. In plant cells, the cell
wall restricts the expansion, resulting in pressure on the cell wall from within called turgor
pressure. Turgor pressure allows herbaceous plants to stand upright. It is also the determining
factor for how plants regulate the aperture of their stomata.
The membrane can be any thin skin that allows water to pass through it but not ions. So
this includes animal cell membranes. So osmotic pressure happens when you transfer a live animal
from one body of water to another. If the differences between the two bodies of water is very great
and the animal is not built to cope with a sharp change then the animal can die due to Cytolysis
(cell wall bursting). This is called Osmotic shock.
Swim bladder is a gas-filled sac found in the body cavities for the most bony-fishes
(Osteichthyes). The swim bladder has various functions in different fishes, acting as a float which
gives the fish buoyancy, as a lung, as a hearing aid, and as a sound producing organ. In many fishes
it serves two or three of these functions, and in the African and Asiatic knife fishes (Notopteridae)
it may serve all four. The swim bladder contains the same gases that make up air, but often in
different proportions (Hill, 2002)
ENGAGE: I need stability to swim
Fish is the one an aquatic life. It can swim into the deep and shallow level of water. What is
the ability of the fish that able them to swim in the water?
So this story is about the swim bladder that many fish have, but as is true with most better stories,
it will end up being about much more than swimming. A problem associated with swimming,
particularly in deep water, is that we want our body to be buoyancy neutral. Hence, it should have
the same density as the water so we do not have to work to keep from floating to the top or sinking
to the bottom. Since the density of water in the ocean varies with location and time the best solution
is to be able to adjust the effective density of our body to match the water. The adjustment should
be rapid if we are a fast swimmer since we are going to move though water of different density.

4. The body of a fish is denser than water, so fish must compensate for the difference or they
will sink. Many bony fishes have an internal organ called a swim bladder, or gas bladder, that
adjusts their buoyancy through manipulation of gases. In this way, fish can stay at the current water
depth, or ascend or descend without having to waste energy in swimming. The bladder is only
found in bony fishes. The solution to maintaining neutral buoyancy is a bladder containing gas
(the red oval) which can be filled or emptied to achieve the desired density for the whole fish (H,
Pelster B, & Scheid P, 1990)
EMPOWER
Conducting Experiment:
Objective:
To investigate the osmotic properties of swim bladder using the data logger.
Hypothesis:
Swimming bladder is selectively permeable then it will demonstrate osmotic properties.
Material and apparatus:
Swim bladder, sucrose solution, distilled water, pressure sensor, data logger
Method:
i. A fresh swim bladder is used to construct an osmometer (refer diagram)
ii. The bladder is filled with sucrose solution and placed in a beaker of distilled water.
iii. Pressure sensor is used to measure the pressure change inside the swim bladder.

5. Diagram 1: Experiment set up
Diagram 2: fish swim bladder

6. Result:
In this experiment, two setups were prepared. With both setups running in parallel, the pressure
changes within the swim bladders were recorded by a computer. The monitor screen displaying
the results was captured and shown below.
Diagram 3: Table of data and graphs.
Both set up recorded a significant increase in pressure within 26 minutes which is quite good. If
allowance is made between the differences between individual set up by adjusting the scale of the
vertical axis, the curves plotted will bear striking resemblance.

7. Discussion:
i. What happen to the swim bladder in the water?
ii. What does the relationship between selectively permeable of swim bladder and the changes
of pressure in the experiments?
iii. What are the osmotic properties of swim bladder?
iv. Does the different depth effect the pressure on the swim bladder?
v. Does water permeable to the swim bladder?
Conclusion:
The rise in pressure was probably due to osmotic intake of water. The experimental results support
the hypothesis that swim bladder as a living membrane is selectively permeable. The experimental
results also show that swim bladder is an appropriate material for the study of osmosis.

8. ENHANCE:
Why does the fish is unable to swim properly in order to rise to the top of the water? Have
you ever seen this phenomenon before?
This is because of swim bladder disease, also called swim bladder disorder or flipover, is a
common ailment in aquarium fish. The swim bladder is an internal gas-filled organ that contributes
to the ability of a fish to control its buoyancy, and thus to stay at the current water depth without
having to waste energy in swimming. A fish with swim bladder disorder can float nose down tail
up, or can float to the top or sink to the bottom of the aquarium.
CONCLUSION:
A data logger is one of the portable devices that is easy to carry from one place to another.
Moreover, every single data that have been read will be recorded and save in the memory, hence
able to use as a reference. Beside, nowadays many data logging can be found in many science
laboratories. Hence, this will attract student more to explore and learn science in interesting ways.
But, in order to handle these apparatus, it need a high maintenance and very expensive. Sometimes,
one data logger may cost a hundred and also a thousand. Besides, they need to handle with care

9. because they are quite sensitive especially the sensor part. Students may learn new things in order
to handle this apparatus in laboratory as a platform for them to practice before graduated and move
into the real situation out there.
REFERENCES:
H, K., Pelster B, & Scheid P. (1990). CO2 back-diffusion in the swimbladder. Respir Physiol.
Hill, M. (2002). Concise Encylopedia of Bioscience. The McGraw-Hill Companies Inc.