Based in California Merit Sensors Systems designs piezoresis

Solution

Piezoresistance of a semiconductor can be described as the change in resistance caused by an applied strain of the diaphragm.Solid state resistors can be used as pressure and force sensors.

Design limitations:

Piezoresistive sensing is based on MEMS techonology.The carrier concentration near the device surfaces can be affected by charging the dielectric layers used to isolate and seal the micro machined structures. The main disadvantage of piezoresistive gauging using bridge circuits lies in the current requirements in the milliampere range,which cause limitations in the use of these circuits in power sensitive applications.

Calibration techniques:

one of the best calibration procedures is a four point bending technique.This is widely used because a uniform,uniaxial stress state can be easily obtained between two inner supports of the fixture.The reduction of uncertanities in the calibration constants increases the accuracy of the stress measurements.

Medical usage:

Many diagnostic and therapeutic devices incorparate pressure sensors made with piezoresistive semiconductor technology.PRT has number of applications in medical segment like patient monitors, respiratory devices, and drug delivery systems.To meet the demands of the patient, the pressure sensing systems are more in demand.