Microflow meter integrated with an optical sensor

This micro flow meter does not only measure the flow of the gas but also controls the input of the gas in a automatic manner. A micro air turbine of 4000 micrometers diameter has been generated in the silicon chip by bulk micromachining technique. It can rotate up to a speed of 4000 rpm with a jet of air. An optical sensor of 400 micrometers diameter has also been generated in the cavity of the silicon under the turbine blades. The output pulses of the sensor due to the chopping of incident light, by rotation of rotor, can be correlated with the input flow. The control circuit controls the input flow based on closed loop system. This work also presents the effect of temperature on the performance of the micro flow meter. This micro flow meter has the response time in micro seconds in comparison to others having in milli seconds.