Sensing the World: what are sensors?

What are Sensors? They are electronic devices that detect input from the physical environment and respond with an action.

Sensors are everywhere around us. They allow technology to interact with our environment and do incredible things!

Inputs can be from light, heat, motion, moisture, pressure, or even distance. Sensors can take these inputs and can generate output that is converted to a display of data. An example of this would be a rangefinder displaying the distance of a swing in golf. The sensor detects the location of the ball. The device uses that location to output a numerical distance the ball travelled. A similar distance sensor example is used in automatic braking in a car.

What are Sensors?

Types of Sensor

There are a broad range of sensors that can use multiple aspects of the environment. We usually classify them as either active or passive. An active sensor is one that requires a power source to be able to respond to environmental input and generate an output. Examples of active sensors are accelerometers, thermistors, and sonar. Passive, on the other hand, doesn’t require an external power source. They use the environment itself for power, using aspects like light or thermal energy. Examples of passive sensors are photographic, infrared, and seismic.

Some are available in both active and passive forms, such as seismic and infrared light sensors. The environment in which the sensor is deployed determines which type is best suited.

Another way in which sensors can be classified is analog and digital. The type of output produced determines whether they are analog or digital. In simple terms, analog signals use a varying range of values while digital signals use an exact range of values. Analog sensors convert the environmental input into continuous and varying output. Digital sensors convert the environmental input into discrete digital signals in a binary format (1’s and 0’s).

Examples of sensors

Distance Sensor

Distance sensors are active-analog and they measure the distance between itself and an object. They do this by emitting a signal and measuring how long it takes to return to the transducer. They are used in situations where someone needs to determine the distance to an. A real example of this would be a car automatically braking when it gets close to another object.

Thermal Sensor

Thermal sensors can be either passive or active. They measure temperature by generating an electrical voltage when a temperature change occurs. They measure that change by measuring the voltage across the diode terminals. When the voltage increases, it is because the temperature increased.

Image Sensor

Image sensors are analog and can be both active or passive. They converts an optical image into an electronic signal. Image sensors are utilized in digital cameras to transform the light received on the camera lens into a digital image. Another use is the digital scanning of QR Codes. These work by using your phone’s system processor interpreting the data the camera sensor gets from reading the blocks and squares that make up the QR Code.

Pressure Sensor

Pressure sensors are active-analog and convert perceived pressure into an electronic signal. An example of this would be to measure oil, fuel, and brake pressure in vehicles. Another example would be a scale to measure weight.


Accelerometers are passive sensors that can be digital or analog. They measure the vibration, or acceleration of motion, of an object. This works because the force caused by vibration, or a change in motion (acceleration), causes the mass to “squeeze” the material in the sensor that produces an electrical charge. A very common application for accelerometers is in cars. Those sensors allow the car to show how fast you are speeding up on the road. Other examples are in cell phones, which allow action based on different touches to the screen, or movement of the phone.

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If you would like more information, or to learn more about sensors, just call or email and we’ll be happy to assist you! If you have specific questions, or if our terminology isn’t clear, please use our contact form to send us a message. Thank you!

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