Multi-range silicon micromachined flow sensor

A new approach of enlarging the measurement range of a thermal calorimetric flow sensor is presented. It is based on the fact that the response of these kind of sensors tends to saturate at a certain flow ratio, so the widening of the flow range can be achieved by increasing the number of sensing elements of the sensor. This implies only a redesign of the flow sensor device, which is fabricated with an existing standard low cost technology. This approach has been implemented achieving measurement ranges from 0.1 up to 8 SLM by placing three different pairs of sensing resistors on the same membrane. Characterisation results and a simulation-based procedure to design flow sensors according to specific applications are included.