Measurement of fluid flow rate using nanocomposite silicone rubber sensor

Abstract

This paper describes the use of an elastic nanocomposite sensor to measure the water flow rate in open and closed hydraulic circuits. A sensor was constructed of multiwalled carbon nanotubes (MWCNTs) dispersed in silicone rubber (SR) and subsequently tested to verify its ability to measure water flow rate. The results reveal that the correlation between the fluid flow rate and the pressure variation across the sensor entails that its electrical resistance can be correlated to the flow rate. The sensor constructed of 2 and 3 wt,% of MWCNTs in SR-based nanocomposite sensors exhibited a low percolation threshold. An electron microscope (HRSEM) was used to characterize the manufactured nanocomposite sensors and confirm the conductive networks. The variation in the electrical resistance of the sensor in terms of both water pressure and flow rate is described. The elastic sensor was calibrated to measure the water flow rate in the range of 0–35 l/min. The results show that an elastic sensor fabricated from MWCNTs dispersed in silicone rubber does exhibit sensitivity to the slight strain levels produced by dynamic water pressure and, as such, can be used to measure flow rate. In addition, the sensor's response to water flow in the presence of bubbles enables pump cavitation monitoring. This paper also investigates the reduction of sensor electrical conductivity in response to water immersion. The findings reveal that the elastic nanocomposite sensor could potentially be used as a liquid sensor to detect water leakage in hydraulic circuits.