3. What is sensor?
An object that detects changes or events in the environment and produces
A type of transducer
Example: A thermometer
5. SMOKE DETECTOR
A device that senses smoke typically as an indicator of fire
Size-150 mm in diameter and 25 mm in thickness
Optical smoke detector contains no radioactive material
Ionisation smoke detectors are cheaper than other types of smoke alarms
Carbon monoxide alarms are used in addition to smoke alarms for increased
Needs regular checking and replacement of batteries
Triggers false alarms when installed near steam rooms, stoves, toaster ovens
and high dust areas
Optical smoke detectors are expensive
Parking sensors are used for alert the driver to obstacles
These sensors use electromagnetic or ultrasonic sensors.
The parking sensor is called as Reverse Aid which was
invented by Dr . Tony Heyes.
After patenting the sensor , Heyes offered it to Jaguar cars.
11. Electromagnetic System
These sensor was invented by Mauro Del Signore In 1992.
These sensors rely on the vehicle moving slowly and
smoothly towards the object to be avoided.
These sensors are mounts on the inner side of the bumper.
12. Ultrasonic Systems
These systems feature ultrasonic proximity detectors to
measure the distances to nearby objects through sensors.
Rear sensors are activated by selecting the reverse gear
and deactivated by selecting other gear.
These system may not detect flat objects or large object to
These sensors are driven by intermittent waves called
Pedometer is a sensor that is used to count the steps
taken by the person.
They are becoming popular as an exercise counter and
These sensors are integrated into electronic devices.
The first pedometer was developed by Abraham-Louis
The technology includes a mechanical sensor and
software to count steps.
Advanced step counters relay on MEMS interial sensors
and software to detect steps.
Pedometer are accurate at flat surface.
22. Applications of Pressure
Level / depth sensing
23. What is an Accelerometer?
An accelerometer is an ELECTROMECHANICAL device
that measures acceleration ("g-force") forces which may
be STATIC, or they could be DYNAMIC.
These are sensing transducers that provide an output
proportional to acceleration, vibration, and shock.
Accelerometers are available that can measure
acceleration in one, two, or three orthogonal axes.
MODES OF USAGE
For inertial measurement of velocity and position.
As a inclination, tilt, or orientation sensor.
As a vibration or shock sensor.
24. Types and working of
Heat transfer(changes in heat)
Hall effect(change in magnetic field)
25. Working of capacitive and
s.no capacitive piezoelectric
1. Output voltage depends on
the distance between two
Output voltage depends on the
pressure exerted on the crystal
2. Changing the gap between
the plates changes the
electrical capacity of the
system, which can be
measured as output.
Mass exerted over the crystal
may produce piezoelectric effect
due to which the voltage is
adv high accuracy and stability. no need for electric supply to
sense, used to measure shock
A Supply is needed Not used to measure g force
26. Working of accelerometer chip in mobiles
Below the red electrode, and separated from it by an air gap,
there's a second electrode (purple).
The air gap between the two electrodes means the red and
purple electrodes work together as a capacitor.
As you move the accelerometer and the red electrode moves
up and down, the distance between the red and purple
electrodes changes, and so does the capacitance between
them hence an equivalent voltage output is produced.
Number of axes
Output range (maximum swing)
Sensitivity (voltage output per g)
To measure tilt angle.
To sense movement.
In laptops to protect hard drives from damage.
Airbag deployment systems for modern automobiles.
In self-balancing robots, auto pilot mode.
physical therapy devices.
In wireless gaming consoles and mobile phones.
28. Recent applications.
In drones and other flying objects
Seismometers-used to measure earthquakes
And also to record earthquake
To measure cable noise(produced due to