Question

llustrate what are the differences between the sensors and transducers, then classify the following
items into Sensors and Transducers with an example.
1. Digital temperature measurement item.
2. EMG measurement item.
3. The digital blood pressure measurement device.
4. Respirometry machine.
92 Classify the following items into Direct and Indirect measurements, sampling or continuous, and
real or delayed time signals, mentioning the reason behind your choice:
1. EEG signal measurement, to analyse the phyological behaviour of the brain.
2. Temprature measurement, to detect the degree of infection of the body.
3. CT scan image of the heart, to measure the volume of the heart.
4. The digital blood pressure measurement device, to measure the response to blood pressue related
medicine.
5. EOG signal, to measure the visual defects in eye (like farsightedness, astigmatism, and presbyopia).
Q3 In a strain gage sensor made of Copper, find the resistance of a copper bar that has a cross-sectional
area of 0.5 mm , length of 250 mm, and the resistivity of copper is 1.7*10-2.m.
Q4 Explain the principle of work of optic sensors used in the blood pressure measurement process.
Q5 When it come to displacement sensors, we have many types of electrodes. Make a comparison between
them with respect to the size, usability, risks, and accuracy
Q6 Response time and Linearity is an important factor to choose a sensor for medical applications.
Explain how can we reduce the time response and increase the linearity of it.
Q7 What is the G-factor in the strain gage, and why do we need to use materials with a high G-factors
in strain gages used for medical purposes.
98 Illustrate the differences bentween the normal inductive snesors and the LVDT, in terms of accuricy.
and size.
Q9 Comapare between the capacitive sensors and piezoelectric sensors in terms of accuricy.
Q10 Comapare between the thermocouples sensors and thermistors sensors in terms of accuricy.

Answer 1

Sensors and Transducers are both electrical devices that are capable of measuring certain physical quantities. But they have a subtle difference in their functionalities.

SENSOR: Sensors are electrical/mechanical devices that detects when there is a change in the observed physical quantity. Effectively speaking, sensor changes a measurable physical quantity(temperature) into an observable physical change(like change in height of mercury level)

TRANSDUCER: In simple language, transducer is a device that converts one form of energy to another. It is especially an electronic device that transforms the non-electrical attribute of any physical quantity into an electrical signal which are easy to manipulate and work around.

Transducer has three major part- i) A sensor, ii) Processing device, iii) Output device

Sensor

Transducer

The major function of sensor is to sense any change in the physical quantity under observation.

The Major function of a transducer is to convert one form of energy into another which can be easily measured.

The major part is the sensor itself.

The major part is the signal processing device. The sensor is also a part of the transducer.

Generally, the output of a sensor is not easy to understand.

After an appropriate signal processing of the output from an sensor, the output of a transducer gives a physical meaning

With the help of sensor, we can appreciate when there is only a change in the measuable quantity.

With the help of transducer, we can appreciate the change as well as measure the physical quantity itself.

eg- motion sensor, photo sensor

eg- thermistor, ECG

1. Digital temperature measurement: This is a transducer. It contains a thermocouple(a sensor) which measures the change in the temperature and converts it into a digital signal. After appropriate signal processing, we are able to detect the exact temperature of the a body.

2.EMG measurement item: This is a transducer. It contain a motion sensor that changes the fluctuation in muscle movement. The transducer converts the motion of muscle into a electric signal whose signal processing finally helps us monitor the (internal)muscle movement. There is also another equipment ECG which works in similar lines.

3. Digital Blood Pressure Measurement device: This is also a transducer. It contains a sensor that measures change in pressure. It is converted into an electrical signal for further processing and finally we are able to measure the blood pressure.

4. Respirometry machine: This is also a transducer. It monitors a patient's respiratory discomfort and assists in breathing. The vitals of the patient are monitored constantly which are basically electrical signals that comes from different sensor fitted in the patient's body.

The answer to question no.3 is given below(handwritten)