Question 1

pressure sensor types

Accepted Answer

There are many types of pressure sensors. Such as resistance strain gauge pressure sensor. Semiconductor strain gauge pressure sensor. Piezoresistive pressure sensor. Inductive pressure sensor. Capacitive pressure sensor. Resonant pressure sensor, etc.

At present, the widely used pressure sensors include: diffused silicon piezoresistive pressure sensors, ceramic piezoresistive pressure sensors, sputtering film pressure sensors, capacitive pressure sensors, and sapphire pressure sensors with high temperature resistance.

But the most widely used is the piezoresistive pressure sensor, which has extremely low price, high precision and good linearity.

Extended reading: What is an air pressure transducer?

Question 2

piezoresistive pressure sensor working principle

Accepted Answer

When the semiconductor silicon material is subjected to force, the atomic lattice changes.
That is, the spacing of the lattice changes. Then the carrier mobility of the silicon material changes.
changes, and the concentration changes. The lateral distribution structure and longitudinal distribution of carriers are disturbed.
The distribution structure of the material eventually leads to a change in the resistivity of the material. The above is half of the
A detailed elaboration of the piezoresistive effect of conductor silicon materials.

A pressure sensor that is also widely used, that is, a resistance strain sensor. Compared with a piezoresistive pressure sensor, the working process or working principle between the two is essentially different.

Piezoresistive Effect of Semiconductor Silicon Piezoresistive Pressure Sensor and Strain Effect of Metal Strain Gauge
The difference between the two should be: the output power of the former, that is, the change of the resistance value mainly depends on the material.
The change of the resistivity of the material. The output power of the latter, that is, the change of the resistance value depends on
Changes in material geometry (strain.

The sensitivity of semiconductor silicon material is high, and its sensitivity is 50 to 100 times that of metal strain gauges.

In 1954, Smith devoted himself to researching the piezoresistive effect of semiconductor silicon material. At the same time, he used it to make pressure sensors.

The silicon pressure sensor researched in the early stage is similar to the semiconductor strain gauge. After development and research, the N-type silicon wafer is doped with P-type impurities by diffusion or ion implantation. The resistance bar is customized. It is matched behind the resistance bar Connect a suitable bridge circuit to make an integrated chip.

It is the same as the use of resistance strain gauges. The chip cannot be used independently to complete the measurement work. It also needs to be firmly attached to the elastic element to sense the change in the measured pressure.

Diffused silicon piezoresistive pressure sensor refers to a sensor made by using the above-mentioned chip as a sensitive element.

Question 3

Diffused Silicon Piezoresistive Pressure Sensors

Accepted Answer

The piezoresistive chip of the piezoresistive pressure sensor is packaged in a shell, and the periphery is fixed to form a silicon cup structure.

On the circular silicon diaphragm, four resistance strips with equal resistance value are made by the above-mentioned diffusion or ion implantation doping method.

Put two of them in the range of compressive stress. The other two are fixed in the range of tensile stress. Together they form a Wheatstone bridge measurement circuit.

Resistor strips are drawn from the bridge power supply terminal and output terminal.

The above-mentioned structure is packaged by the manufacturing method of an integrated circuit to obtain a diffused silicon piezoresistive pressure sensor.

Question 4

capacitive pressure sensor

Accepted Answer

Capacitive pressure sensor is a pressure sensor that uses capacitive sensitive elements to convert the measured pressure into an electrical output that has a certain relationship with it. The characteristics are that the input energy is low, the dynamic response is high, the natural effect is small, and the environmental adaptability is good.

It generally uses a circular metal film z or a metal-plated film as an electrode of the capacitor. When the film is deformed by pressure, the capacitance formed between the film and the fixed electrode changes. The output can be in a certain relationship with the voltage by measuring the circuit. electrical signal.

Capacitive pressure sensors belong to the polar distance variable capacitive sensors. They can be divided into single capacitive pressure sensors and differential capacitive pressure sensors

Question 5

MEMS piezoresistive pressure sensor

Accepted Answer

Current MEMS pressure sensors include silicon piezoresistive pressure sensors and silicon capacitive pressure sensors. Both are microelectromechanical sensors produced on silicon wafers.

The silicon piezoresistive pressure sensor uses high-precision semiconductor resistance strain gauges to form a Wheatstone bridge as a force-electricity conversion measurement circuit. It has high measurement accuracy, low power consumption and extremely low cost. Piezoresistive sensor for a Wheatstone bridge. If there is no pressure change, its output is zero and almost no power consumption.

Capacitive pressure sensors use MEMS technology to create a grid-like shape on a silicon wafer. The upper and lower two transverse barriers become a group of capacitive pressure sensors. The upper transverse grille is displaced downward by pressure. Changed the spacing between the upper and lower transverse grids. It also changes the size of the capacitance between the plates, that is, △ pressure = △ capacitance.

Extended reading: Industrial Pressure Transmitters|Buy from the manufacturer

Month: May 2019

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