MEMS-based pressure sensor with a superoleophobic membrane for measuring droplet vibration

We report on a sensor design to measure the vibration of small droplets. The sensor consists of a piezoresistive cantilever and a chamber covered with a superoleophobic membrane. The vibration of a droplet on the membrane causes the pressure of the chamber to change. Since the cantilever is able to detect a pressure change of less than 0.1 Pa, the vibration of the droplet can be precisely measured by the cantilever. In comparison to previously developed MEMS-based force sensor to measure the droplet vibration, the current sensor design offers several benefits including: wide range of usable liquids, simple sensing scheme (only one sensor is required) and capability to be disposable. With these advantages, our method is believed to be useful in measuring viscosity of small droplet for point-of-care application.