Banner Sensors - Introduction to the applications and characteristics of various types of sensors

1. Resistive type

A resistive sensor is a device that converts measured physical quantities such as displacement, deformation, force, acceleration, humidity, temperature, etc. into resistance values. There are mainly resistive strain gauge, piezoresistive type, thermal resistance, thermal, gas sensitive, moisture sensitive and other resistive sensing devices.

2. Weighing

A load cell is a power-electricity conversion device that converts gravity into an electrical signal, and is a key component of an electronic scale. There are many kinds of sensors that can realize power-electricity conversion, and the common ones are resistive strain type, electromagnetic force type, and capacitive type. The electromagnetic force type is mainly used for electronic balances, the capacitive type is used in some electronic crane scales, and the vast majority of scale products are still used for resistance strain gauge load cells. The resistance strain gauge load cell has a simple structure, high accuracy, wide application, and can be used in a relatively poor environment. Therefore, resistance strain gauge load cells are widely used in scales.

3. Piezoresistive type

Piezoresistive sensors are devices made by diffusion resistance on the substrate of semiconductor materials according to the piezoresistive effect of semiconductor materials. The substrate can be used directly as a measurement sensing element, and the diffusion resistance is connected to the substrate in the form of a bridge. When the substrate is deformed by an external force, the resistance values will change, and the bridge will produce a corresponding unbalanced output.

The substrate (or diaphragm) materials used as piezoresistive sensors are mainly silicon wafers and germanium wafers, and silicon piezoresistive sensors made of silicon wafers as sensitive materials have attracted more and more attention, especially for solid-state piezoresistive sensors that measure pressure and velocity.

4. Laser

A sensor that uses laser technology to make measurements. It consists of a laser, a laser detector, and a measurement circuit. The laser sensor is a new type of measuring instrument, which has the advantage of being able to achieve non-contact long-distance measurement, fast speed, high precision, large range, strong anti-light and electrical interference ability, etc.

When the laser sensor works, the laser emitting diode is first aimed at the target to emit a laser pulse. After being reflected by the target, the laser light is scattered in all directions. Part of the scattered light is returned to the sensor receiver, where it is received by the optical system and imaged onto the avalanche photodiode. An avalanche photodiode is an optical sensor with an internal amplification function, so it can detect extremely weak optical signals and convert them into corresponding electrical signals. The high directivity, high monochromaticity, and high brightness of the laser can be used to measure remotely without contact.

5. Hall

Hall sensor is a kind of magnetic field sensor made according to the Hall effect, which is widely used in industrial automation technology, detection technology and information processing. The Hall effect is a fundamental method for studying the properties of semiconductor materials. The Hall coefficient measured by the Hall effect experiment can determine the conductive type, carrier concentration and carrier mobility of semiconductor materials.

6. Biology

Biosensor is an interdisciplinary discipline that organically combines bioactive materials (enzymes, proteins, DNA, antibodies, antigens, biofilms, etc.) with physical and chemical transducers, which is an advanced detection method and monitoring method indispensable for the development of biotechnology, and is also a rapid and micro-analysis method at the molecular level of substances.

All kinds of biosensors have the following common structure: including one or more related bioactive materials (biofilms) and physical or chemical transducers (sensors) that can convert bioactive expression signals into electrical signals, the two are combined to reprocess biological signals with modern microelectronics and automated instrumentation technology to form various biosensor analysis devices, instruments and systems that can be used.

7. Temperature

A temperature sensor is a sensor that senses the temperature and converts it into a usable output signal. Temperature sensors are the heart of temperature measuring instruments and come in a wide variety of varieties. According to the measurement method, it can be divided into two categories: contact and non-contact, and according to the characteristics of sensor materials and electronic components, it can be divided into two categories: thermal resistance and thermocouple.

8. Contact type

The detection part of the contact temperature sensor has good contact with the measured object, also known as the thermometer. The thermometer achieves thermal equilibrium by conduction or convection, so that the thermometer's indication directly represents the temperature of the object being measured.

In general, the measurement accuracy is high. The carburized glass thermal resistance made by carburizing and sintering porous high silica glass is a kind of temperature sensing element of the cryogenic thermometer, which can be used to measure the temperature in the range of 1.6-300K.

9. Contactless

Its sensitive elements are not in contact with the measured object, also known as non-contact temperature measuring instrument. This instrument can be used to measure the surface temperature of moving objects, small targets, and objects with small heat capacity or rapid temperature changes (transients), as well as to measure the temperature distribution of the temperature field. The most commonly used non-contact temperature measuring instruments are based on the basic law of blackbody radiation, known as radiometric thermometers. Radiometric thermometry includes luminance (see Optical pyrometers), radiometry (see Radiation pyrometers), and colorimetric methods (see Colorimetric thermometers).

Advantages of non-contact temperature measurement: The upper limit of measurement is not limited by the temperature resistance of the temperature sensing element, so there is no limit to the maximum measurable temperature in principle. For high temperatures above 1800°C, non-contact temperature measurement methods are mainly used. With the development of infrared technology, radiation temperature measurement has gradually expanded from visible light to infrared, and has been used below 700 °C until room temperature, and the resolution is very high.

10. Thermocouples

Thermocouples are the most commonly used temperature sensors for temperature measurements. Its main benefits are a wide temperature range and adaptability to a wide range of atmospheric environments, as well as being robust, inexpensive, without the need for power supply, and the cheapest. A thermocouple consists of two different metal wires (metal A and metal B) connected at one end, and when one end of the thermocouple is heated, there is a potential difference in the thermocouple circuit. The temperature can be calculated using the measured potential difference.

11. Thermistor

Thermistors are made of semiconductor materials, and most of them have a negative temperature coefficient, that is, the resistance value decreases with the increase of temperature. Temperature changes can cause large resistance changes, so it is the most sensitive temperature sensor. However, the linearity of thermistors is extremely poor and has a lot to do with the production process. Manufacturers can't give a standardized thermistor curve.

12. Accelerometer

An accelerometer is a type of sensor that is capable of measuring acceleration. It is usually composed of mass, damper, elastic element, sensitive element and adaptation circuit. During the acceleration process, the sensor uses Newton's second law to obtain the acceleration value by measuring the inertial force on the mass. Depending on the sensor sensing element, common accelerometers include capacitive, inductive, strain, piezoresistive, piezoelectric, etc.

13. Piezoelectric

Piezoelectric accelerometers are also known as piezoelectric accelerometers. It is also an inertial sensor. The principle of piezoelectric accelerometers is to use the piezoelectric effect of piezoelectric ceramics or quartz crystals, and when the accelerometer is vibrate, the force of the mass on the piezoelectric element also changes. When the measured vibration frequency is much lower than the natural frequency of the accelerometer, the change in force is proportional to the measured acceleration.

14. Piezoresistive

Based on the world's leading MEMS silicon micromachining technology, piezoresistive accelerometers have the characteristics of small size and low power consumption, and are easy to integrate in various analog and digital circuits, and are widely used in automotive crash experiments, test instruments, equipment vibration monitoring and other fields.

15. Capacitive

Capacitive accelerometers are capacitive sensors with varying pole distance based on the capacitance principle. Capacitive accelerometers/capacitive accelerometers are more versatile accelerometers. There are no substitutes in some areas, such as airbags, mobile phones, mobile devices, etc. Capacitive accelerometers/capacitive accelerometers use a microelectromechanical systems (MEMS) process that is economical when produced in large quantities, thus guaranteeing low costs.

16. Servo type

The servo accelerometer is a closed-loop test system with good dynamics, large dynamic range and good linearity. Its working principle, the vibration system of the sensor is composed of "m-k" system, the same as the general accelerometer, but the mass m is also followed by an electromagnetic coil, when there is acceleration input on the base, the mass deviates from the equilibrium position, the displacement magnitude is detected by the displacement sensor, and is converted into current output after amplification by servo amplifier, and this current flows through the electromagnetic coil, produces electromagnetic restoring force in the magnetic field of the permanent magnet, and tries to keep the mass in the original equilibrium position in the instrument housing, So the servo accelerometer works in a closed-loop state.

17. Fiber optic sensor

The basic working principle of the optical fiber sensor is to send the optical signal from the light source to the modulator through the optical fiber, so that the parameters to be measured interact with the light entering the modulation area, resulting in the optical properties of the light (such as the intensity, wavelength, frequency, phase, polarization state, etc.) of the light change, becoming the modulated signal source, and then sent to the optical detector through the optical fiber, after demodulation, the measured parameters are obtained.

18. Thermocouple sensing

A thermocouple consists of two metal wires of different materials that are welded together at the ends. By measuring the ambient temperature of the unheated part, the temperature of the heating point can be accurately known. Since it must have two conductors of different materials, it is called a thermocouple. Thermocouples made of different materials are used in different temperature ranges, and their sensitivity is also different. The sensitivity of a thermocouple is the amount by which the output potential difference changes when the temperature of the heating point changes by 1°C. For most metal-supported thermocouples, this is between 5 and 40 μV/°C.

Banner Sensors - Introduction to the applications and characteristics of various types of sensors

Sections viewed

Contact

working hours