A sensor is a component that works by detecting an event or a change in the surrounding physical environment and producing output that is in accordance with its function.
In an electronic system, a sensor is a type of transducer that has a function to process inputs such as sound, vibration, motion, heat, light, magnetic and chemical into a voltage or electric current which is then processed to produce an output.
A transducer is a device that converts one form of power into another form of power for a specific purpose. The transducer can be electrical, electronic, electromagnetic, photonic or photovaltic equipment.
The way the sensor works is determined by the type and function of the sensor, but still has similarities in detecting changes and processing them. The energy processed by the sensor aims to support the performance of electronic devices that use the sensor itself.
Types of Sensors
Basically the types of sensors can be divided into 8 kinds. Of the 8 types of sensors, there are 3 types of sensors that are most often used in various electronic circuits, such as light or light sensors, temperature sensors and pressure sensors. But it’s a good idea to know all the types of resistors that exist.
1. Light Sensor
Is a sensor that converts light energy into electrical energy, which is also often called a photosensor. This type of sensor is used for objects that have the form of color or light and then processed into different powers.
Light sensors are divided into 3 types, including:
- Photovoltaic or solar cells, is a type of sensor that functions to convert light energy directly into electrical energy, with the irradiation will cause the movement of electrons and generate voltage.
- Photoconductive, is a sensor that provides a change in resistance (resistance) in the cells caused by the energy received. The brighter the energy given, the smaller the value of the resistance, and vice versa if it is darker, the value of the resistance is getting bigger.
- Photoelectric, this sensor has a way of working based on the reflection due to changes in the position or distance of the light source (infrared or laser) or the reflector.
Some examples of components of this light sensor are LDR (Light Dependent Resistor), Photodiode, Phototransistor and one example is used in price detectors in various supermarkets or infrared on mobile phones
2. Temperature Sensor
As the name suggests, this sensor is used to detect a temperature. Sensors of this type can be divided into 4 main types, including:
- Thermocouple (T/C), which is a device consisting of a pair of different transducers then connected and melted together, where there is a difference between the connection and the reference connection that serves as a comparison.
- Pressure Temperature Detector or Resistant Temperature Detector (RTD) is an electrical resistance of metal that varies in proportion to temperature. This proportionality of variation is a precision with a high level of consistency/stability in resistance detection. The material commonly used in RTD is platinum because it has linearity, stability and reproducibility.
- Thermistor, is a type of resistor that is sensitive to heat which usually has a negative temperature coefficient. Because when the temperature increases, the resistance will decrease and vice versa. The thermistor component is very sensitive to changes (5% resistance per oC) so it is able to detect small changes in temperature.
- IC Sensor, is a type of sensor with an integrated circuit that uses a silicon chip for the element that acts as a sensor. It has a very linear voltage and current output configuration. Sensors of this type are widely installed in smoke detector equipment which is also used to track fires.
3. Pressure Sensor
This type of sensor uses a transducer that works to measure wire tension, which converts the mechanical stress into an electrical signal. The basis for sensing is the change in introductory resistance (transducer) due to changes in length and cross-sectional area.
One example of equipment that uses a pressure sensor is a tool to detect adult blood pressure automatically.
4. Speed Sensor
Is a sensor that is used to detect the speed of motion of an object which is then processed into an electrical signal format. The workings of this type of sensor is that the sensing process is the opposite of a motor, where a shaft/object rotating on a generator will produce a voltage that corresponds to the rotational speed of the object.
Rotational speed is also often measured using a sensor that senses a magnetic pulse (induction) that occurs when a magnetic field occurs.
5. Ultrasonic Sensor
This type of sensor works based on the principle of sound wave reflection, which is able to produce sound waves which are then captured again with a time difference as the basis for sensing.
The time difference between the emitted sound wave and the recapture is directly proportional to the distance or height of the object that reflects it. Types of objects that can be sensed include solid, liquid, granular and textile objects. Several devices or products have used this type of sensor, one of which is the Robot on KRCI.
6. Magnetic Sensor
Is a device that is affected by a magnetic field and is able to provide a change in the conditions of the output. This type of sensor is often referred to as a reed relay. Generally, this type of sensor is packaged in a vacuum and free from dust, moisture, smoke or steam.
The use of this sensor can be in the form of computer-based magnetic field measurements consisting of a magnetic field sensor UGN3503, Op-Amp LM358 and ADC 0804. The working principle is to bring the magnet closer to the sensor. The sensor output results in the form of a voltage which is then amplified by the Op-Amp so that it can be processed by the ADC.
Then the voltage is converted by the ADC into digital data, and processed again by the computer with a visual basic program, which then results are displayed on the PC.
7. Encoding Sensor
This type of sensor serves to convert linear motion or rotation into a digital signal, where the rotation sensor monitors the rotary motion of a tool. Usually this sensor is composed of 2 layers of encoding types, namely:
- The first is an additional rotary encoder (transmits a certain number of pulses for each round) and will generate a square wave on the object being rotated.
- Second, namely the Absolute Encoder (Completing a certain binary code for each angular position) and has the same work with the exception that more or more square wave pulses are generated so as to form an encoding in a certain order.
8. Proximity Sensor
A sensor that is able to detect the presence of an object that is nearby without making direct physical contact. These sensors are often referred to as proximity sensors and are usually composed of solid-state electronics that are tightly encased to protect against excessive vibration, liquid, chemical, and corrosive effects.
This type of sensor can be applied to sensing conditions on objects that are considered too small or soft to actuate a mechanical switch. One example of the use of this sensor is on a smartphone which in the process of its application uses the Air-Gesture technique. The use of which can manage access to the smartphone without any physical contact to the smartphone screen.
From the explanation of the definition and types of sensors above, it can be said that sensors have an important role in various technologies. Of these types of sensors, each has different specifications and functions for each use in various electronic equipment.