Capacitive transducers are sensors that measure changes in capacitance to detect various physical parameters such as displacement, pressure, and humidity. They operate on the principle of variable capacitance, with movable plates allowing for changes in distance and area that affect capacitance. Capacitive transducers are advantageous due to their high sensitivity and accuracy but can be sensitive to temperature and humidity.

1. CAPACITIVE
TRANSDUCERS

2. Capacitive Transducer
Capacitance transducers are a type of sensor that measures changes in capacitance (the
ability of a material to store electric charge) to detect physical parameters such as:
1. Displacement (position, movement)
2. Pressure
3. Force
4. Acceleration
5. Vibration
6. Humidity
7. Liquid level

3. Working principle
 The working principle of a capacitive transducer is variable capacitance. As per its
structure, these are having two parallel metal pates which are maintaining the distance
between them. In between them, dielectric medium (such as air) can be filled. So, the
distance between these two metal plates and positions of the plates can change the
capacitance. So, variable capacitance is the principle of these transducers. The basic
difference between the normal capacitors and capacitive transducers is, the
capacitor plates are constant in normal capacitors wherein these transducers, capacitor
plates are the movable condition.

4. Types of Capacitive Transducer
According to the structure of the capacitive transducer, they are four types which are
discussed below. They are
Parallel plate capacitance with rectangular plates.
Cylindrical capacitor transducer.
Semi circular parallel plates.
Change in dielectric between parallel plates.

5. Parallel plate capacitance with rectangular plates
This is also called a flat type of capacitive transducer. In this type of transducer, one
plate is fixed and the other plate can be moved. By this variation, the distance d or area
A can be varied. This results in the capacitance value of this transducer.

6. Semi Circular Capacitive Transducer
This type will provide the highest capacitance value when the two capacitive plates are
overlapped to each other. These are preferable when the circuit requires the maximum
capacitance.

7. Cylindrical Capacitive Transducer
Considering the length of the cylinder is to be L, then the capacitance

8. Change in Dielectric Medium between
Parallel Plates
When the dielectric medium varies between the two parallel plates of this transducer,
that also varies the capacitance of the transducer.
Therefore, capacitance C= εo (ε1*L1*w + ε2*L2*w)/d
Here – L1 and L2 are indicating the length of the 1st and 2nd plates length.
W indicates the width of the plate
D indicates the distance between the plates

9. Advantages of Capacitive Transducer
The capacitive transducer advantages are discussed below. They are
1. High sensitivity
2. Low power consumption
3. Compact size
4. Non-contact measurement
5. High accuracy.

10. Disadvantages of Capacitive Transducer
There are a few disadvantages of a capacitive transducer are listed below. They
are
1. Sensitivity to temperature
2. Humidity effects
3. Noise susceptibility
4. High frequency limitations
5. Expensive

11. Applications of Capacitive Transducer
The Applications of the capacitive transducer are
1. Industrial automation
2. Aerospace engineering
3. Medical devices
4. Automotive systems
5. Consumer electronics