What is the MEMS pressure sensor?
A MEMS pressure sensor is one of the most mature and widely adopted types of MEMS sensors. Its function is to detect pressure in the environment or in a medium (absolute pressure, gauge pressure, or differential pressure) and convert it into a usable electrical output signal.
Operating Principle
The vast majority of MEMS pressure sensors operate based on the piezoresistive effect or capacitive change principle. Taking the most common piezoresistive MEMS pressure sensor as an example:
The core of the sensor is a thin diaphragm/membrane fabricated through micromachining, with a vacuum or reference pressure cavity typically formed underneath it.
Piezoresistive elements (materials whose resistance changes when subjected to mechanical stress) are integrated on or near the surface of the diaphragm.
When external pressure is applied to the diaphragm, it bends and deforms, exerting stress on the piezoresistive elements and thereby altering their resistance values.
These resistors are typically arranged in a Wheatstone bridge configuration to convert small resistance changes into a measurable voltage signal.
Electronic circuits then amplify, temperature-compensate, and linearize the signal, ultimately outputting a standardized signal proportional to the pressure value.
Main Classifications
Absolute Pressure Sensor, Reference to a sealed vacuum chamber; measures pressure relative to vacuum
Gauge Pressure Sensor,Reference to local atmospheric pressure; measures pressure relative to ambient air
Differential Pressure Sensor,Measures the pressure difference between two distinct pressure sources
Typical Application Fields
Automotive Electronics: Tire Pressure Monitoring Systems (TPMS), fuel injection control, Exhaust Gas Recirculation (EGR) systems;
Consumer Electronics: Barometers in smartphones and tablets (assisting GPS positioning and altitude measurement), height tracking in smartwatches;
Industrial Automation: Process control, pneumatic equipment, hydraulic system monitoring;
Healthcare: Ventilators, blood pressure monitors, negative-pressure wound therapy devices;
Aerospace: Cabin pressure monitoring, altimeters.
MEMS pressure sensors have become the dominant technology for pressure measurement due to their high sensitivity, excellent linearity, long-term stability, low cost, and suitability for batch fabrication.