Wide-range flow meter for air and gases

Abstract

This paper presents a new wide-range sensor for measuring of the gas flow. The flow meter was developed on the base of the new way of measurement, which makes adaptation of measuring procedure. It extends the measurement range of the sensor without losing of accuracy. The sensor is implemented on the basis of the thin-film MEMS structures and the system on a chip, thus minimizing the number of components and to provide a set of standard digital interfaces. A generic aspect of the sensor is an original closed-loop conditioning approach. Using the thermal delay of the temperature waves as a function of gas flow, self oscillations are excited. This “electro-physical” generator realizes an analog-to-frequency conversion of the measuring value. Besides the feedback scheme should improve the sensor performance. The Sensor is made practically on one microcircuit with digital interface due to use PSoC. That has provided high accuracy and low prime cost of the device as a whole.