A Micro-machined viscosity-variation monitoring device using propagation of acoustic waves in microchannels

Abstract

A new viscosity-variation monitoring device for measuring viscosity changes in small amounts of liquid in real time is designed and fabricated. The device is specifically developed to evaluate the physical characteristics of liquids that are readily changeable and/or difficult to obtain in larger quantities, such as biomaterials. It is capable of monitoring the viscosity variation of a sample as small as 13 nl. The device is composed of two chambers connected by multi-microchannels and is fabricated using MEMS (micro-electro-mechanical system) technology. Each chamber has a unimorphic piezoelectric diaphragm for generating and sensing sound waves. One chamber is regarded as an actuator and the other as a sensor. Viscosity variations can then be quickly and easily measured by detecting the signal output obtained from the sensor for either a continuous or tone-burst single-frequency input to the actuator. The performance of the device is ascertained by experiments performed on test samples with various viscosities.