We are all living in a world of sensors. Sensors are everywhere, from our mobile phones to wristwatches to UAVs to airplanes to satellites. Even our own body has them (in the form of sensory organs). Sensors can be easily dubbed as the building blocks of automation. Many of the automated processes/manufacturing that we take for granted are possible because of sensors. How many types of sensors are there? And where are these sensors used? We’ll answer these questions in upcoming sections. So let’s get cracking.
What is Sensor?
A sensor is defined as a device that responds to a physical stimulus (such as heat, light, sound, pressure, magnetism, or a particular motion) and transmits a resulting impulse (as for measurement or operating a control).
A sensor is a device that detects changes in input stimuli/quantities like pressure, temperature, humidity, speed, etc, and generates an output quantity (mostly in the form of current or voltage) as a result of these changes.
To read more on what is a sensor, click here!
Keeping that in mind, there are many sensors for many applications. So how are we going to distinguish them? Let’s start with that.
Types of Sensors
There are two types of sensors:
- Direct Sensor: A sensor that can convert a non-electrical stimulus into an electrical signal with intermediate stages. Eg: thermocouple (temperature to voltage).
- Indirect Sensor: A sensor that multiple conversion steps to transform the measured signal into an electrical signal. Eg: fiber-optic displacement sensor (light current to photons to current).
Now, remember all of the sensors can be classified mainly into these two types. But there are other ways to classify them.
- Active and Passive Sensors
- Contact and Non-contact sensors
- Absolute and Relative Sensors
Let’s get to know these types better and see what sensors fall into these categories.
- Active Sensor is a sensor that requires external power to operate. It is also known as a parametric sensor i.e. output is a function of the parameter.
- Passive Sensor is a sensor that generates its own electric signal and does not require a power source. It is also called a self-generating sensor.
- Contact Sensor is a sensor that requires physical contact with the stimulus.
- Non-contact Sensor does not require physical contact with the stimulus.
- Absolute Sensor is a sensor that reacts to a stimulus on an absolute scale.
- Relative Sensor is the sensor where the stimulus sensed is relative to a fixed or variable reference.
List of Sensors
Here is a list of all the sensors that are most commonly used.
- Infrared Sensor (IR Sensor)
The IR sensor is an electronic device that measures and detects infrared radiation in its surrounding environment. Or in simple words, it is a light-emitting diode that can detect the change in color, heat, and IR radiation.
Read more on the IR sensor here.
- Temperature Sensor
Temperature Sensors measure the amount of heat energy or even coldness that is generated by an object or system, allowing us to “sense” or detect any physical change to that temperature producing either an analog or digital output.
You can read more about the temperature sensor here.
- Proximity Sensor
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact. A proximity sensor often emits an electromagnetic field or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal. The object being sensed is often referred to as the proximity sensor’s target. Different proximity sensor targets demand different sensors.
- Ultrasonic Sensor
An ultrasonic sensor is an electronic device that measures the distance of a target object by emitting ultrasonic sound waves and converts the reflected sound into an electrical signal.
An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is acceleration in a fixed coordinate system.
- Gyroscope Sensor
A gyroscope sensor is a device that can measure and maintain the orientation and angular velocity of an object. These are more advanced than accelerometers. These can measure the tilt and lateral orientation of the object
- Pressure Sensor
A pressure sensor is a device for pressure measurement of gases or liquids. The pressure is an expression of the force required to stop a fluid from expanding and is usually stated in terms of force per unit area. A pressure sensor usually acts as a transducer; it generates a signal as a function of the pressure imposed
- Hall Effect Sensor
A Hall effect sensor is a device that is used to measure the magnitude of a magnetic field. Its output voltage is directly proportional to the magnetic field strength through it. Hall effect sensors are used for proximity sensing, positioning, speed detection, and current sensing applications.
- Load cell
A load cell is a type of transducer, specifically a force transducer. It converts a force such as tension, compression, pressure, or torque into an electrical signal that can be measured and standardized. As the force applied to the load cell increases, the electrical signal changes proportionally.
- Light Sensor
The light sensor is a passive device that converts this “light energy” whether visible or in the infra-red parts of the spectrum into an electrical signal output. Light sensors are more commonly known as “Photoelectric Devices” or “Photo Sensors” because the convert light energy (photons) into electricity (electrons).
- Color Sensor
A color sensor detects the color of the material. This sensor usually detects color in the RBG scale. This sensor can categorize the color as red, blue, or green. These sensors are also equipped with filters to reject the unwanted IR light and UV light.
- Touch Sensor
Touch Sensors are the electronic sensors that can detect touch. They operate as a switch when touched. These sensors are used in lamps, touch screens of the mobile, etc… Touch sensors offer an intuitive user interface.
- Tilt Sensor
A tilt sensor is an instrument that is used for measuring the change in tilt and monitoring of inclination and vertical rotation in vertical structures. The tilt sensor produces an electrical signal which is proportional to the degree of tilt in multiple axes (Uniaxial & Biaxial).
- Vibration Sensor
The vibration sensor is also called a piezoelectric sensor. These sensors are flexible devices that are used for measuring various processes.
- Water Flow Sensor
A water flow sensor measures the rate of flow of water and calculates the amount of water flowed through the pipe. The rate of flow of water is measured as liters per hour or cubic meters.
- Heartbeat Sensor
Heartbeat Sensor is an electronic device that is used to measure the heart rate i.e. speed of the heartbeat.
- Level Sensor
Level sensors detect the level of liquids and other fluids and fluidized solids, including slurries, granular materials, and powders that exhibit an upper free surface.
- Gas Sensor
Gas sensors (also known as gas detectors) are electronic devices that detect and identify different types of gasses. They are commonly used to detect toxic or explosive gasses and measure gas concentration
- Soil Moisture Sensor
The soil moisture sensor is a kind of sensor used to measure the volumetric content of water within the soil.
- Rotary Encoder
A rotary encoder, also called a shaft encoder, is an electro-mechanical device that converts the angular position or motion of a shaft or axle to an analog or digital output signals.
A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute (RPM) on a calibrated analog dial, but digital displays are increasingly common.
All of these sensors fall into multiple types so distinguishing them would only add to the confusion which is not the intent of this article. Hope this will help you in understanding what is a sensor, the different types as well as a list of most commonly used sensors. Tune in to this space to learn more about these sensors. And don’t forget, Keep Learning!!