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G. Sowmya Padukone et al.
[1] is its resolution. It means the least change in the output that could be detected for
the minimum changes in the input applied.
The following are the some of the types of sensors:
(i) Thermal sensor, (ii) speed sensor, (iii) accoustic sensor, (iv) chemical sensor,
(v) optical sensor, etc.
First let us see optical sensor. It is an instrument or a device which transforms light
signals to electrical signals. The output of an optical sensor can be easily deciphered
by a readable device. An optical sensor mainly consists of a transmitter and a receiver.
Optical sensors are an integral part of most of the electronic devices like Xerox
machines, scanning machines, printers, computers, etc.
Different types of optical sensors are: (i) photo-conductive devices, (ii) photovoltaic cell, and (iii) photodiodes. All these devices take input as light energy and
convert to other form of energy. The optical sensor based on hydrogen material is
known to be as highly sensitive [2] optical fiber. It is having a fast time response with
respect to input and output.
Optical sensors are also mainly used for biomedical applications. The following
are some of the applications of optical sensors in the field of medicine (Fig. 1).
Optical heart rate sensor is the one which is placed on the wrist of a user. By
measuring the variation of the movement of blood, the corresponding heart rate will
be detected and given to the sensor in a readable form. Almost all optical biosensors
have sensitivity of around parts per billion. The water level content present in the
human body can also be measured by using optical sensor. Optical heart rate sensor
uses the flow of blood to assess the heart beat rate.
Whenever the light passes through the tissue, where optical sensor is placed, then
if there is more volume of blood in that region, it gives less-calibrated output at the
output. If there is low volume of blood in that region where the sensor is placed, then
it returns a high-calibrated [3] value to the corresponding detector. It uses a technique
called as photoplethysmography (PPG) to calibrate the heart rate. The heart beat
rate for a normal and healthy person is around 60–100 beats per minute.
Fig. 1 a Optical heart rate sensor b tunable diode laser used for breath analysis
G. Sowmya Padukone et al.
[1] is its resolution. It means the least change in the output that could be detected for
the minimum changes in the input applied.
The following are the some of the types of sensors:
(i) Thermal sensor, (ii) speed sensor, (iii) accoustic sensor, (iv) chemical sensor,
(v) optical sensor, etc.
First let us see optical sensor. It is an instrument or a device which transforms light
signals to electrical signals. The output of an optical sensor can be easily deciphered
by a readable device. An optical sensor mainly consists of a transmitter and a receiver.
Optical sensors are an integral part of most of the electronic devices like Xerox
machines, scanning machines, printers, computers, etc.
Different types of optical sensors are: (i) photo-conductive devices, (ii) photovoltaic cell, and (iii) photodiodes. All these devices take input as light energy and
convert to other form of energy. The optical sensor based on hydrogen material is
known to be as highly sensitive [2] optical fiber. It is having a fast time response with
respect to input and output.
Optical sensors are also mainly used for biomedical applications. The following
are some of the applications of optical sensors in the field of medicine (Fig. 1).
Optical heart rate sensor is the one which is placed on the wrist of a user. By
measuring the variation of the movement of blood, the corresponding heart rate will
be detected and given to the sensor in a readable form. Almost all optical biosensors
have sensitivity of around parts per billion. The water level content present in the
human body can also be measured by using optical sensor. Optical heart rate sensor
uses the flow of blood to assess the heart beat rate.
Whenever the light passes through the tissue, where optical sensor is placed, then
if there is more volume of blood in that region, it gives less-calibrated output at the
output. If there is low volume of blood in that region where the sensor is placed, then
it returns a high-calibrated [3] value to the corresponding detector. It uses a technique
called as photoplethysmography (PPG) to calibrate the heart rate. The heart beat
rate for a normal and healthy person is around 60–100 beats per minute.
Fig. 1 a Optical heart rate sensor b tunable diode laser used for breath analysis