Smart flow sensors based on advanced packaging techniques applied to single chip sensing devices

A smart flow sensor capable of measuring two distinct gas flows with two different linearity ranges is proposed. The device is based on a chip, designed with a commercial CMOS process, which includes different sensing structures and a read-out interface. The chip is fabricated applying a post-processing technique based on a silicon anisotropic etching in a TMAH solution. A simple and low cost packaging technique is used to convey two distinct gas flows to two selected sensing structures by means of channels of different cross sections. Three methods for sealing the interface between the chip and the gas conveyor are proposed and discussed.