This type of pressure sensor consists of a micro-machined
silicon diaphragm with piezoresistive strain gauges diffused
into it, fused to a silicon or glass backplate.
The resistors have a value of approx. 3.5 kOhm. Pressure
induced strain increases the value of the radial resistors (r),
and decreases the value of the resistors (t) transverse to
the radius. This resistance change can be high as 30%.
The resistors are connected as a Wheatstone Bridge, the
output of which is directly proportional to the pressure.
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