What is the structure of the piezoresistive pressure sensor

Piezoresistor pressure sensor is a sensor made of piezoresistor effect of monocrystalline silicon and integrated circuit technology. When the monocrystalline silicon material is affected by the force, the resistivity changes, through measuring circuit, ratiometric output signal to force change can be obtained. It is also known as the diffused silicon piezoresistive pressure sensor, which is different from the adhesive strain gauge which needs to feel the external force indirectly through the elastic sensitive element, but directly through the silicon diaphragm to feel the measured pressure.

Structure and features

The principle of piezoresistor pressure sensor is that the resistance changes after the sensitive core is pressed, and then the resistance changes are converted into standard signal output by the amplifier circuit.

Currently, there are three general types of piezoresistive cores:

（1） Principle of strain:

① Structure: Piezoresistor is combined with strain material (usually stainless steel) by the form of wheatstone bridge.

② features: overload capacity, strong impact resistance but low sensitivity, suitable for measuring high pressure above 500kpa, the highest range up to 500Mpa, vibration resistance, not easy to damage, small temperature drift, high range (over 1Mpa) good linearity, high precision diaphragm structure, suitable for measuring all kinds of media compatible with strain materials.

（2）Principle of piezoresistive ceramic:

① structure: Piezoresistor is sintered with ceramics by the form of wheatstone bridge.

② features: Overload capacity is lower than strain principle, but higher sensitivity to impact pressure, suitable for measuring the high range above 50kpa, maximum range of 40Mpa, wide temperature range.

（3）Principle of diffusion silicon:

① structure: Injecting particles into silicon wafers by the form of wheatstone bridge.

② features: high sensitivity, high precision, suitable for measuring the range of 1kpa ~ 40Mpa, strong overpressure capacity, good impact pressure, large temperature drift.

it is divided into 2 categories: ① non-isolating diaphragm can only measure clean gas. ② Isolating diaphragm is stainless steel material suitable for measuring media compatible to stainless steel.

Shanghai TM sensor’s OEM pressure sensor is belong to diffusion silicon pressure sensor, output is ratiometric mV output, and 0.5~4.5V output. Smart construction and various output mode, can be applied in various industrial requirement.