Silicon flow sensor

A silicon flow sensing element formed by a single silicon chip, the flow sensing element comprising:

• a base region having a surface;
• a vane cantilevered from the base region and adapted to deflect relative to the base region when impinged by fluid flow, the vane having a surface contiguous with the surface of the base region;
• a beam region intermediate the vane and the base region;
• means for sensing strain in the beam region occurring as a result of the vane being deflected relative to the base region;
• and
• means defined by the chip for affecting the sensitivity of the vane to fluid flow.

A bidirectional piezoresistive silicon flow sensor including a single silicon chip within a sensor package, the chip comprising:

• a base region having a thickness in a direction of fluid flow;
• a vane cantilevered from the base region and adapted to deflect when impinged by fluid flow, the vane having a thickness in the direction of fluid flow, the thickness of the vane being less than the thickness of the base region, the vane having a width transverse to the direction of fluid flow;
• a beam region intermediate the vane and the base region, the beam having a width transverse to the direction of fluid flow, the width of the beam being less than the width of the vane;
• a piezoresistor disposed on the beam region for sensing strain occurring in the beam region as a result of the vane being deflected relative to the base region in the direction of fluid flow;
• and
• a frame disposed along a peripheral edge of the vane so as to form a gap therebetween, the gap being adapted to affect the sensitivity of the vane, the frame securing the chip to the sensor package.