We live in a World of Sensors. You can discover various types of sensors in our homes, workplaces, vehicles, and so on. Attempting to make our lives simpler by turning on the lights recognizing our presence, controlling room temperature, identifying smoke or fire, automatic door opener, and numerous different tasks. All these automation tasks are conceivable due to sensors.
Now take a look for a detailed description of sensors, types of sensors, and their applications.
What is Sensor?
There are numerous definitions as to what the sensor is but I would like to define a Sensor as an input device that provides an output (signal) with respect to a specific physical quantity.
The term “input device” in the definition of a Sensor means that it is part of a bigger system that provides input to the main control system (like a Processor or a Microcontroller).
Another unique definition of a sensor is as follows: It is a device that converts signals from one energy domain to the electrical domain. The definition of the Sensor can be understood if we take an example into consideration.
The simplest example of a sensor is an LDR or a Light Dependent Resistor. It is a device, whose resistance varies according to the intensity of light it is subjected to. When the light falling on an LDR is more, its resistance becomes very less and when the light is less, well, the resistance of the LDR becomes very high.
We can connect this LDR to a voltage divider (along with other resistors) and check the voltage drop across the LDR. This voltage can be calibrated to the amount of light falling on the LDR. Hence, a Light Sensor.
Now that we have seen what a sensor is, we will proceed further with the classification of sensors.
Classification of Sensors
There are several classifications of sensors made by different authors and experts. Some are very simple and some are very complex. The following classification of sensors may already be used by an expert in the subject but this is a very simple classification of sensors.
In the first classification of the sensors, they are divided into Active and Passive. Active Sensors are those which require an external excitation signal or a power signal.
Passive Sensors, on the other hand, do not require any external power signal and directly generate output response.
The other type of classification is based on the means of detection used in the sensor. Some of the means of detection are Electric, Biological, Chemical, Radioactive etc.
The next classification is based on the conversion phenomenon i.e. the input and the output. Some of the common conversion phenomena are Photoelectric, Thermoelectric, Electrochemical, Electromagnetic, Thermooptic, etc.
The final classification of the sensors is Analog and Digital Sensors. Analog Sensors produce an analog output i.e. a continuous output signal with respect to the quantity being measured.
Digital Sensors, in contrast to Analog Sensors, work with discrete or digital data. The data in digital sensors, which are used for conversion and transmission, is digital in nature.
How Many Types of Sensors
Coming up next is a list of various types of sensors that are normally utilized in different electronic applications. All of these sensors are used for estimating the physical properties like Temperature, Resistance, Capacitance, Conduction, Heat Transfer, and so on.
- Temperature Sensor
- Proximity Sensor
- Infrared Sensor
- Pressure Sensor
- Light Sensor
- Ultrasonic Sensor
- Smoke, Gas and Alcohol Sensor
- Touch Sensor
- Colour Sensor
- Humidity Sensor
- Tilt Sensor
- Flow and Level Sensor
We will see around a couple of the previously mentioned sensors in a word. More data about the sensors will be included along these lines. A list of projects utilizing the above sensors is given toward the end of the page.
One of the most common and most popular sensors is the Temperature Sensor. A Temperature Sensor, as the name suggests, senses the temperature i.e. it measures the changes in the temperature.
In a Temperature Sensor, the changes in the Temperature correspond to changes in its physical property like resistance or voltage.
There are different types of Temperature Sensors like Temperature Sensor ICs (like LM35), Thermistors, Thermocouples, RTD (Resistive Temperature Devices), etc.
Temperature Sensors are used everywhere like computers, mobile phones, automobiles, air conditioning systems, industries etc.
A simple and small project is made by using this sensor here Fire Alarm Sensor.
A Proximity Sensor is a non-contact type sensor that detects the presence of an object. Proximity Sensors can be implemented using different techniques like Optical (like Infrared or Laser), Ultrasonic, Hall Effect, Capacitive, etc.
Some of the applications of Proximity Sensors are Mobile Phones, Cars (Parking Sensors), industries (object alignment), Ground Proximity in aircraft, etc.
A simple and small project is made by using this sensor here Reverse Parking Sensor.
IR Sensor or Infrared sensor is a light-based sensor that is used in various applications like Proximity and Object Detection. IR sensors are used as proximity sensors in almost all mobile phones.
There are two types of Infrared or IR sensors: Transmissive Type and Reflective Type. In the Transmissive Type IR sensor, the IR Transmitter (usually an IR LED) and the IR Detector (usually a Photo Diode) are positioned facing each other so that when an object passes between them, the sensor detects the object.
The other type of IR sensor is a Reflective Type IR sensor. In this, the transmitter and the detector are positioned adjacent to each other facing the object. When an object comes in front of the sensor, the sensor detects the object.
Different applications where IR sensor is implemented are Mobile Phones, Robots, Industrial assembly, automobiles, etc.
A simple and small project is made by using this sensor here DIY Infrared Sensor.
An Ultrasonic Sensor is a non-contact type device that can be used to measure the distance as well as the velocity of an object. An Ultrasonic Sensor works based on the properties of the sound waves with a frequency greater than that of the human audible range.
Using the time of flight of the sound wave, an Ultrasonic Sensor can measure the distance of the object (similar to SONAR). The Doppler Shift property of the sound wave is used to measure the velocity of an object.
A simple and small project is made by using this sensor here Ultrasonic Range Finder.
A Light Detector or a Light Sensor is a device or circuit that detects the intensity of the light incident on it. Different types of light detectors are LDRs (or Light Dependent Resistors), Photo Diodes, Photo Transistors, etc.
All these devices are called as Photoelectric Devices as they convert light energy to electric energy. These Light Detectors or Sensors can detect different types of light as visible light, ultraviolet light, infrared light, etc.
A simple and small project is made by using this sensor here Darkness Detector.
A Smoke detector is a smoke-detecting gadget that shows fire. Smoke alarms are exceptionally normal in homes, workplaces, schools, and industries. Smoke alarms are extremely helpful gadgets as the harm brought about by fire mishaps is disastrous. These days, smoke alarms and smoke cautions are modest as their use is expanding and the expense of assembling is diminishing.
A simple and small project is made by using this sensor here Smoke Detector Alarm.
Alcohol Sensor – Alcohol Breathalyzer
Touch Sensor – Touch Dimmer Switch
Colour Sensor – Color Detector
Humidity Sensor – Humidity Sensor
Tilt Sensor – Tilt Sensor Using Arduino