Transit Time Difference Flowmeter for Intravenous Flow Rate Measurement Using 1-3 Piezoelectric Composite Transducers

The flow rate of injected medication implemented by intravenous (IV) systems must be accurately monitored and meticulously controlled to prevent medical accidents. In this paper, an ultrasonic flowmeter (UF) with 1–3 piezoelectric composite transducers was designed, fabricated, and tested on a variety of flow rates of mimic medical injections. The transducer wedge for the angled beam propagation and an acoustic impedance matching layer were included in the design for transmission enhancement. To ensure an accurate measurement of flow rate, the effect of the flow distributions inside the IV tube was taken into account. The developed UF exhibited the capability of detecting low flow rates (<0.005 m/s), with 1%-2% discrepancy compared with the reference rate of infusion.