A transducer for measuring high frequency oscillatory flow rates.
Recent systems proposed in the literature to accurately measure flow rates at high frequency, such as the wave tube technique or the loudspeaker technique, are not adequate for large amplitude oscillations. Other standard pneumotachometer systems require analytical or numerical correction procedures. In this study, we propose a low cost, rapid response flowmeter for high and low flow rates, made up of a standard screen pneumotachometer coupled with a piezoresistive differential pressure transducer of recent conception. By reference to a gas capacitance, the frequency response of this device is compared to the frequency response obtained with the same screen pneumotachometer coupled with a standard low range medical pressure transducer. Contrary to the standard device, the new device has a flat amplitude response up to 70 Hz and introduces a minimal phase delay up to 90 Hz (9 degrees), both with a 1.51.s-1 constant peak flow and a peak flow rate two times greater. The authors suggest that this improved flowmeter can be advantageously used in physiological studies requiring accurate high frequency flow measurements over short periods of time.
D012123:Pulmonary Ventilation; D012212:Rheology; D012815:Signal Processing, Computer-Assisted; D014160:Transducers, Pressure