Motion sensors detect heat and movement in a surrounding environment called a “protective grid.” If many objects are present in the grid or if an object is moving fast, it changes the infrared energy levels. Motion sensors are typically used for security such as driveway or house alarms as if there is a large fluctuation in infrared levels an alarm will sound signifying there is an extensive amount of activity going on.

There are two main types of motion sensors: active ultrasonic and passive infrared sensor technology. Ultrasonic motion sensors detect sound waves from an environment and bounce back to the sensor as input. If the sound waves are disturbed the intended action will be performed. For example, if someone enters a room the lights will turn on.  Passive infrared sensors detect infrared energy (heat from humans and animals). They detect temperature fluctuation as the input and output the intended action.

Motion sensors have a limited range in which they can word, hence the “grid.” That is why houses have multiple security alarms  in different locations.  A typical range for motion sensors is anywhere from 50 to 80 feet. The programming language used for motion sensors is C or C++. The other programming languages are Matlab, Java, and Python for the development or production phase.

Light sensors measure the amount of light emitted in a surrounding environment and react upon the values imputed into the sensor. However, light is an extensive property when it comes to being measured as depending on the sensor different aspects and the amount of light being collected can vary. For example, a large solar panel will collect more light than the solar panel on a calculator.

Light sensors take measurements in lux which have a base unit called candela. Candela is used to describe “luminous intensity” which is how intense the light is seen to the human eye. It can vary person to person. The luminous intensity is based on the wavelength of the light beam.

Light sensors are typically used to measure distance or an  angle of an object. Light sensors use an element called “photodiode” which measures the brightness of an object. The brighter the light imputed into the senros the stronger the electric current, and the stronger the electric current, the brighter the return of the illuminance of light.

Platforms like Arduino and Raspberry Pi have small light sensors. Java, C++, and recently Python are used to program light sensors into projects. There are also more user friendly platforms like AdaFruit Circuit that are making it easier for people to use light sensors.

Camera sensors use millions of tiny lights called “photosites” to record an image. When an object is in the frame or range of the camera the exposure begins and the tiny light cavities collect photons and store them as electrical signals. After the exposure is complete, the camera closes the photosites and determines how many photons fell into the “cavity array” which ends up producing the final image. The photos are measured by how much electrical signal they produce.

The light cavities do not produce the colors we see as humans. They only create grayscale images. Therefore, in order for the final output to be in color, a filter has to be placed over each cavity in the array. The most common filter placed is called a “Bayer array” which uses red, blue, and green colored filters on top of the photons placed in the initial cavity array. The ayer array consists of a specific pattern of color filters: alternating rows of red-green and green-blue filters. There are more green filters as the human eye is more sensitive to green light. Green light also has finer detail than red or blue filters.

The programming languages used for camera sensors include C#, Ruby, Python, C, and C++. There are also platforms like MagicLantern which people can use, which is written in C.

A load cell is a type of force sensor that converts force into an electrical output which is then used to do a desired action. Strain gauge load cells are the most used force sensors.  A load cell converts mechanical energy, force of an object, into numerical values that a user can read and use in their work. Strain gauge load cells specifically send users voltage irregularities when under load and then presented to the user as weight.

Load cells have 4 different classes: class A, class B, class C, and class D. The different classes show the levels of accuracy and capacity. Load cells are used amongst a wide variety of industries to weight and manage force based on the electrical output. 

Strain gauge load cells are used the most as they are highly accurate and cost effective. The sensor itself is made out of aluminum, alloy steel, or stainless steel to be sturdy to endure the weight of the item being sensed.

Load cells can be programmed using Arduino. Raspberry Pi, Python, and C#. Load cell code samples are also present for the Phidgetbridge sensor. Arduino along with HX711 amplifier will allow users to read load cells to measure weight and code the desired action.