What is Sensor?
A sensor is an apparatus that receives input from the outside environment and processes it. Light, heat, motion, moisture, pressure, and a variety of other environmental phenomena can all be used as inputs.
The output is basically a signal, which is either electronically transferred over a network for reading or additional processing, or transformed into a human-readable display at the sensor location.
Types of Sensors.
There are several ways to classify sensors. A typical method is to categorize them as either passive or active.
Active Sensor: An active sensor is one that needs to be powered externally in order to respond to input from the environment and provide an output.
Passive Sensor: On the other hand, a passive sensor may detect environmental input without the need of an external power source. It draws energy from the environment itself, including thermal and light sources. The mercury-based glass thermometer is a perfect example. Variations in temperature cause the mercury to expand and contract, resulting in variations in the glass tube's level. An easily readable temperature gauge is provided by external markings.
Both active and passive versions of several sensor types are also available, such as infrared light and seismic sensors. Which sort of sensor is ideal for a given application usually depends on the environment in which it is deployed.
Another method to categorize sensors is according to their type of sensor output, according to whether they are digital or analog.
Analog Sensor: Continuous, variable analog signals are produced by analog sensors from environmental input. A good example of an analog sensor is the thermocouple found in all industrial as well as residential application as temperature sensing element.
Digital Sensor: In contrast to the analog sensor, digital sensor's output is discrete digital signals not any continues analog value and that transmitted in a binary(1/0) format. It's output is either "One" or "Zero" that means it is like a simple switch which have only two state ON or OFF.
Similar to active and passive sensors, there are analog and digital versions of several sensor types, such as pressure or temperature sensors. The most suitable option in this case is also usually determined by the environment in which the sensor will function.
Study more: Vibration Sensor Working Principle, Types and Application.
Another popular way to categorize sensors is by the kinds of variables in the environment they are to be monitored or detected. Here are a few typical example of sensors have been developed for measuring physical processes:
Temperature Sensor: These sensors are capable of measuring the target medium's temperature, whether it air, liquid, or gas. A vast variety of equipment and applications, including computers, appliances, machines, airplanes, cars, greenhouses, farms, and thermostats, use temperature sensors.
Pressure Sensor: These sensors measure the pressure of a liquid or gas. Which are widely employed in machinery, vehicles, aircraft, HVAC systems, and other environments. By monitoring air pressure, they also have a significant impact on meteorology.
Level Sensor: The level of a physical substance, such as water, fuel, coolant, grain, fertilizer, or garbage, can be measured using a level sensor. For example, fuel level sensors are used by drivers to make sure they don't get stuck on the side of the road.
Accelerometer: This kind of sensor measures tilt, vibration, and, of course, acceleration by detecting variations in gravitational acceleration. Many different industries, including consumer electronics, professional sports, aerospace, and aviation, use accelerometer sensors.
Proximity Sensor: Proximity sensors measure the distance between subjects or identify their presence. The purpose of proximity sensors is to find the existence of any physical object in the surrounding area without direct physical touch. In order to detect and return the presence of a physical object in close proximity, it may emits an electromagnetic field of radiation or light or sound within its range. A wide range of circumstances, including robotics, parking lots, stores, elevators, and manufacturing process lines, use proximity sensors as monitors.
Optical Sensor: Optical sensors, also known as photosensors, can detect light waves at different wavelengths in the light spectrum, including ultraviolet, visible, and infrared light. Optical sensors are widely utilized in cellphones, robots, Blu-ray players, home security systems, medical devices, and a variety of other applications.
Humidity Sensor: These sensors can detect the presence of water vapors in the air and determine relative humidity. Humidity sensors usually provide temperature information since relative humidity is proportional to air temperature. These sensors are utilized in a variety of industries and environments, including agriculture, industry, data centers, meteorology, and heating, ventilation, and air conditioning (HVAC).
Chemical Sensor: Chemical sensors detect particular chemical substances within a media like gas, liquid, or solid. A chemical sensor can detect soil nutrient levels in a crop field, smoke or carbon monoxide in a room, pH levels in a body of water, the quantity of alcohol on someone's breath, or in a variety of other environments. For example, an oxygen sensor in a car's emission control system will measure the fuel-to-oxygen ratio using a chemical reaction that produces a voltage. A computer in the engine compartment reads the voltage and compares it to the needed value; if the mixture is not optimal, the ratio is adjusted accordingly.
Motion Sensor: Motion detectors detect physical movement inside a specific area (the field of detection) and can be used to control lights, cameras, parking gates, water faucets, security systems, automated door openers, and a variety of other appliances. These sensors typically emit some form of energy, such as microwaves, ultrasonic waves, or laser beams, and can detect when the flow of energy is interrupted by something in its path.
Touch Sensor: Touch detecting devices detect physical contact when touching the monitored surface. Touch sensors are widely utilized in electronic gadgets to enable trackpad and touchscreen technology. They are also utilized in a variety of other applications, including elevators, robots, and soap dispensers.
The examples above are only a few of the many different types of sensors that are utilized in various contexts and systems. However, none of these categories are black and white; for example, a level sensor that monitors a material's level might equally be classified as an optic or pressure sensor. There are numerous additional different types of sensors, including ones that can detect load, strain, color, sound, and a wide range of other variables. Sensors are becoming so widely used that they are often overlooked by people.
Study more: RPM Sensor: Working Principle, Types and Applications.
Through our work place we can found some sensors by name, these all can be categorized among the above discussed classifications. Now we will go through some sensors like that.
- RTDs, thermocouples, and thermoistors: a trio for temperature measurement instrument belongs to temperature sensor.
- Strain gauges: used to quantify the strain—such as pressure, tension, weight, etc.—on an object
- Load cells: used to calculate loads and weights
- LVDT sensors: Distance displacement is measured with LVDTs.
- Microphones: to record audio waves
- Current transducers: used to measure DC or AC current
- Voltage transformers: to measure high voltage potentials
- Camera sensors: utilized to record both continuous and single 2D images
- GPS: Positioning sensors are used to record the longitudinal and latitudinal position.
- PIR sensor
- Tilt sensor
Strain gage sensor
Applications of strain gauges
- Measurements of stress and strain
- Measurements of weight and load
- Measurement of force
- Measurements of shock and vibration
- Data collection on road loads
Ultrasonic Sensor
An ultrasonic sensor uses ultrasonic sound wave emissions to determine the distance between the sensor and a targeted item. An ultrasonic sensor has a transmitter that generates and emits sound waves using piezoelectric crystals, and a receiver that picks up any sound waves that are reflected back from the targeted object. Which is then picked up and transformed into digital or electrical signals for processing.
What do the Sensor do?
A sensor is an apparatus that senses changes in its surroundings and responses to an output from another system. It transforms a physical input into a quantifiable analog voltage or current (or occasionally a digital signal like switch on/off), which is then sent for reading or additional processing or transformed into a display that is viewable by humans.
A widely recognized sensor is the microphone, which transforms sound waves into an electrical signal suitable for amplification, transmission, recording, and replication.
One very ancient form of sensor used to measure temperature is the ordinary mercury thermometer. It is based on the fact that colored mercury reacts linearly and consistently to temperature changes when used in a closed tube.
