What Are Sensors? How Do They Work?

Image: Robin Glauser / Unsplash

A sensor is a key component in electronic devices that detects an occurrence in its physical environment. It checks for external stimuli and sends the corresponding electrical signal to an interface from where the signal changes into computer-readable language. This signal is then displayed on an electronic screen or passed on further to facilitate another process.

The physical occurrences that a sensor can detect encompass motion, light, temperature, sound, and much more. Accordingly, they are called motion sensors, light sensors, sound sensors, etc.

These sensors are present in a broad range of devices around us. For instance, smartphones come with various built-in sensors such as an accelerometer, a magnetometer, a gyroscope, et al. Moreover, the booming field of the Internet Of Things (IoT) has all kinds of sensors at its core.

electronics with sensors
Most electronic devices have various sensors in them. (Image: Pixabay / Pexels)

Categories of Sensors

Active sensors

These sensors emit radiation to detect changes in their surroundings. They work by analyzing the reflection of the emitted waves back from the target object. Some technologies that use active sensors are LiDAR, radar, GPS, sonar, etc.

Passive sensors

Passive sensors do not radiate waves of their own, but they are receptive to external radiation. They work by sensing the radiation produced by their target object. These sensors are employed in infrared, electric field sensing, seismic, and thermal technologies.

Different types of sensors and how they work

Motion sensors

These sensors are present in devices such as smart lights and automatic doors. They usually emit an ultraviolet, microwave, or some other type of wave, which causes the motion sensor light to turn on or off when interrupted by an object.

Sound sensors

Sound sensors are commonly found in smartphones, security alarms, smart lights, etc. These devices have a sound-sensitive diaphragm that vibrates when it encounters sound waves. This results in producing an electrical signal that is amplified and digitized to detect the right sound intensity.

Light sensors

This type of sensor uses a high-precision photoelectric tube that produces an electric current whenever it detects light. There are a number of devices that use light sensors, such as automobiles, smartphones, solar cells, and more.

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