A Bi-directional Silicon Orifice Flow Sensor Characterised For Fluid Temperature And Pressure

A bi-directional silicon orifice flow sensor for gases has been realised using an industrial sensor process. Characterisation has been performed with both a piezoresistor Wheatstone bridge configuration and with a novel Sigma-Delta converter providing digital read-out. Sensitivities of 0.044 mV/V(mg/sec)* or 5.7 counts/(mg/sec)' have been measured. Due to the symmetric design, the sensitivity is independent of the flow direction.