A responsive viscosity sensing system with a flow channel based on a one-port resonator

Abstract

Recently, more and more SAW sensors have been developed for viscosity sensing, bringing different ways of contacting the liquid with the device. It is important to choose a contact method that maximizes the performance of the device. Therefore, this paper describes the development of devices for detecting the viscosity of liquids and the evolution of fluid-device contact methods. And a responsive viscosity sensing system with a flow channel for real-time monitoring is developed in our work. The channel, made of polycarbonate, is responsible for regulating the flow direction and ensures that the sensing area covered by the liquid, the mass, and the morphology of the liquid load on the sensor are the same for each detection. Based on a one-port resonator, the sensor offers a faster response time, lower attenuation, and higher sensitivity of 38.6 kHz/ kg m−2 s−0.5. The real-time detection results also show that changes in flow rate do not affect resonant frequency. In addition, the sensor's frequency response to viscosity-density product has been conducted using glycerol solution to get a standard curve. Then the viscosity of the rinse water can be accessible by the frequency response. For the first time, the rinse solution directly from the washing machine is used to measure the residual detergent concentration. The residual concentrations of detergent in the first and second rinse solutions are 23 ppm and 6 ppm, respectively. The system is more convenient, more responsive, and more accurate.