Integrated silicon flow-direction sensor

Abstract Thermal flow sensors can be made in silicon using standard planar technology, which has the advantage of mass fabrication of identical devices and the possibility of combining the sensor with on-chip signal-processing circuitry. Already a large number of sensors have been reported that use the total heat loss from the sensor to the flow. These sensors have a number of disadvantages, including limited directional sensitivity, which makes flow direction sensing difficult. Using the detection of on-chip temperature differences, it is possible to measure the flow direction independent of the flow magnitude. By combining flow direction and flow magnitude measurements, a full two-dimensional flow sensor can be realized. In this article the attention is focussed on how the flow direction can be measured based on thermal measurements.