How do sensors work

They look at human senses and their electronic imitators, with special focus on the nervous system, skin and touch sensors. Through four lesson and four activities, students are introduced to the logic behind programming. The unit is designed to be motivational for student learning, so th Students learn about electric motors and rotational sensors. They learn that motors convert electrical energy to mechanical energy and typically include rotational sensors to enable distance measuring.

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Curriculum in this Unit Units serve as guides to a particular content or subject area. So, the varying potential can be further used to measure the amount of change in temperature. A strain gauge is used to detect pressure when a load is applied. The same principle can be used here to measure the load. On a flexible board, a wire is arranged in a zig-zag manner as shown in the figure below. So, when the pressure is applied to that particular board, it bends in a direction causing the change in overall length and cross-sectional area of the wire.

This leads to change in resistance of the wire. The resistance thus obtained is very minute few ohms which can be determined with the help of the Wheatstone bridge. The strain gauge is placed in one of the four arms in a bridge with the remaining values unchanged.

Therefore, when the pressure is applied to it as the resistance changes the current passing through the bridge varies and pressure can be calculated. Strain gauges are majorly used to calculate the amount of pressure that an airplane wing can withstand and it is also used to measure the number of vehicles allowable on a particular road etc.

Load cells are similar to strain gauges which measure the physical quantity like force and give the output in form of electrical signals. When some tension is applied on the load cell it structure varies causing the change in resistance and finally, its value can be calibrated using a Wheatstone bridge. Here is the project on how to measure weight using Load cell. A potentiometer is used to detect the position. It generally has various ranges of resistors connected to different poles of the switch.

A potentiometer can be either rotary or linear type. In rotary type, a wiper is connected to a long shaft which can be rotated. When the shaft has rotated the position of the wiper alters such that the resultant resistance varies causing the change in the output voltage. Thus the output can be calibrated to detect the change its position. To detect the change in the position an encoder can also be used. It has a circular rotatable disk-like structure with specific openings in between such that when the IR rays or light rays pass through it only a few light rays get detected.

Further, these rays are encoded into a digital data in terms of binary which represents the specific position. The name itself states that it is the sensor which works on the Hall Effect.

It can be defined as when a magnetic field is brought close to the current carrying conductor perpendicular to the direction of the electric field then a potential difference is developed across the given conductor.

Using this property a Hall sensor is used to detect the magnetic field and gives output in terms of voltage. Care should be taken that the Hall sensor can detect only one pole of the magnet. The hall sensor is used in few smartphones which are helpful in turning off the screen when the flap cover which has a magnet in it is closed onto the screen. Here is one practical application of Hall Effect sensor in Door Alarm.

A FLEX sensor is a transducer which changes its resistance when its shape is changed or when it is bent. A FLEX sensor is 2. It is shown in the figure. This change in resistance can do no good unless we can read them. The next level is to use optics to do the sensing itself, both augmenting and replacing conventional technology sensors like strain gauges, accelerometers, temperature sensors, and more. More about this new trend will be added to this article in the near future, so please check back.

In addition to sensor performance, another advantage is the fiber optic transmission of the sensor data itself compared to using copper cables. Today, fiber optics are being used instead of electrical transmission to send signals from one point to another.

We see this even in our own homes, where fiber is used to bring television and the internet to our homes at transmission speeds that are higher than conventional cable. Fiber optical transmission also provides several distinct advantages over electrical transmission, including:.

We think of cameras as something only used to take pictures or movies, but they are heavily used in all kinds of industrial and scientific applications as well. Factories use single and continuous image sensor cameras aka video cameras to monitor and control a wide variety of fabrication and assembly line processes.

Cameras are also an important part of DAQ system measurement applications. Datafile recorded with the Dewesoft DAQ system showing analog and digital data synchronized with the video. On one end of the capabilities spectrum, it is possible to use a very inexpensive web camera to add a video to your recordings in some DAQ systems. For example, the DS-CAM shown here can output up to frames per second at full HD resolution, and up to frames per second if the size of the image is reduced.

The camera is also sealed to IP 67 so that it can be used in wet, dusty, and harsh environments. Within Dewesoft DAQ systems , multiple cameras can be used at the same time, providing different viewing angles of the object s under test. The next logical step was using industrial cameras whose frame rates could be precisely controlled, and which offered better resolution and speed.

Infrared cameras are also sometimes used in scientific and industrial applications and are another important sensor for DAQ applications. Data file export from the Dewesoft X using synchronized analog data, IR and standard cameras. Infrared is extremely useful in troubleshooting in power plants because power supplies and generators that are hotter than normal indicate a problem.

With one look using an IR camera is it easy to see trouble spots. The same is true with automotive brake testing, where IR cameras make it possible to measure the precise temperature of the brakes in operation and measure accurately how fast they heat up and cool down under a variety of conditions.

They are being used more and more in ADAS advanced driver assistance systems , as they allow the car to detect people and other sources of thermal energy before they come into view, especially at night. The best-known maker of IR cameras is FLIR , and Dewesoft has integrated many of their cameras seamlessly into their DAQ systems so that continuous thermographic data can be acquired in sync with the analog and digital sensor data, as shown in the example above.

High-speed cameras are useful for capturing extremely fast-changing events. An assortment of high-speed video cameras from Photron. High-speed cameras from Photron capture up to , pictures per second. This data is captured to RAM and then is immediately available for replay. It is possible to synchronize Dewesoft DAQ systems with Photron cameras so that they are both triggered at the same time, and when the test is over, the high-speed video is immediately transferred to the Dewesoft DAQ system and automatically synchronized with the other data.

You can replay it in perfect sync with all the data from other sensors. Video from a fuse switch test using Dewesoft DAQ equipment and software. Cameras provide a unique context to the data that engineers record, adding a vital layer of information and understanding to countless research and testing applications. When we talk about digital sensors, we refer to those sensors that output discrete values, usually related to the linear or angular position, as well as those sensors that are used to detect when an object is nearby.

A proximity sensor is able to detect a nearby object without making contact with it, and then output a pulse or voltage signal. There are several types of proximity sensors, which are chosen based on the composition of the object s that should be detected. Typical proximity sensor. Many encoders can also detect the direction of rotation, which is essential in some applications.

Typical Rotary Encoder. Incremental encoders report relative changes in position and direction - they do not track absolute position angle. Incremental encoders output A and B signals, which indicate changes in movement and direction. When this position is reached an additional Z output signal is generated. Incremental encoders are the most common and popular types of encoders.

A linear encoder measures position along a linear path. Unlike a rotary encoder which has a circular plate inside that allows it to measure shaft position, most linear encoders move along an external scale and determine their position from markings on the scale. Linear Encoder Image courtesy of Heidenhain.

A perfect example is an inkjet printer, which uses a linear encoder to precisely move the printhead back and forth along a scale during printing.

High resolution and accuracy are obviously required in this and countless other applications. The most prevalent sensing technology used with linear encoders is optical, however, there are encoders that also employ magnetic, capacitive and inductive technology.

Optical encoders provide the most accuracy and the highest possible resolution, however, care must be taken to prevent contaminants from interfering with their operation. There are both analog and digital output linear encoders. Dewesoft systems are better suited to digital outputs since they provide A and B outputs very similar to incremental rotary encoders as described in the previous section.

For example, a heat sensor called a thermistor changes its ability to allow the flow of electric charges through it in response to temperature. By placing a thermistor in an electrical circuit, the current can be switched on or off in another part of the circuit, such as turning off a heater if the air gets too hot. Just as sensors in the human skin send impulses to the brain where the information is analysed and we feel hot or cold, in machines, electronics are used to analyse the physical conditions being sensed through changes in electric current.

Sensors react to changing physical conditions by altering their electrical properties. Thus, most artificial sensors rely on electronic systems to capture, analyse and relay information about the environment. These electronic systems rely on the same principles as electrical circuits to work, so the ability to control the flow of electrical energy is very important. Put simply, a sensor converts stimuli such as heat, light, sound and motion into electrical signals. These signals are passed through an interface that converts them into a binary code and passes this on to a computer to be processed.

Many sensors act as a switch, controlling the flow of electric charges through the circuit. Switches are an important part of electronics as they change the state of the circuit. Components of sensors such as integrated circuits chips , transistors and diodes all contain semiconducting material and are included in the sensor circuits so that they act as switches.

For example, a transistor works by using a small electrical current in one part of the circuit to switch on a large electrical current in another part of the circuit. Most sensors use radiation such as light or laser, infraredradio waves or other waves such as ultrasonic waves to detect objects and changes in their environment.

They can do so by having an energy source inside them that enables them to emit the radiation towards their target object. This radiation is reflected back by the object and detected by the sensor — this is called an active sensor, for example, in the use of radar.