What Are Sensors?
Sensors are devices that detect various types of physical quantities or concentrations of substances.
Also called detectors, sensors are incorporated into all kinds of electronic devices and play a role equivalent to that of sensory organs such as the eyes, ears, and nose. They are used not only to detect the object in real-time, but also to determine the next action of the device or to stop the device from operating for safety reasons.
Sensors convert physical information, such as light and heat, into electrical information, which can be incorporated into electrical circuits to enable automatic operation of electrical equipment.
For example, a temperature sensor is installed in an air conditioner. When the air conditioner is set to a certain temperature, the temperature sensor inside the air conditioner detects the temperature. This information is then transmitted to a microcomputer, which operates the air conditioner so that the indoor temperature equals the set temperature.
How Sensors Work
Temperature Sensors are devices that sense temperature and activate a contact point or change electrical resistance. A device that activates its contacts depending on the temperature is a temperature sensor called a thermostat. Two types of metal plates with different thermal expansion are laminated together, and when a temperature change occurs, the metal plates are disengaged.
A device that changes electrical resistance is a temperature sensor called a thermistor. Thermistors have the characteristic that their electrical resistance changes significantly even with slight changes in temperature. Therefore, for example, when used in heating equipment, fine control is possible, such as gradually reducing the output as the room temperature rises.
Types of Sensors
Sensors can detect heat, pressure, sound, light, distance, flow rate, etc. There are different types of sensors depending on the object to be measured, and the principle of measurement is also different.
For example, smartphones are equipped with a variety of sensors. Touchscreens are equipped with sensors that detect finger contact and movement, and cameras have sensors that detect light and convert it into images. Communication with an AI assistant is made through the microphone, which is also a sensor that detects sound.
In recent years, the rapid proliferation of IoT has led to more and more people adopting smart homes and other devices. For example, when a smart home detects the approach of a person and turns on a light, it uses infrared-based motion sensors to detect the approach of the person.
For example, when a sensor is used to turn on the air conditioner when a person approaches home, the GPS sensor is used to detect the location of the person.
Control of temperature and humidity is important to achieve a comfortable living space, and temperature and humidity sensors are also used here.
Sensors can be categorized according to the five human senses.
- Eye (Sight)
Optical Sensors (Photodiodes, CCD, CMOS, etc.) - Ear (Hearing)
Sound Sensors (piezoelectric elements, condenser microphones, etc.) - Skin (Touch)
Temperature Sensors (Thermocouples, Thermistors, etc.), Pressure Sensors (Diaphragms, Semiconductor Pressure Sensors, etc.) - Nose (Smell)
Smell sensors (semiconductor gas sensors, bio-chemical elements) - Tongue (Taste)
Taste Sensors (PH Sensors, Particle Sensors)
Since there are so many different types of sensors, it is important to carefully consider what to detect and select the appropriate one for your purpose.