PNNL

Abstract

Abstract – Meniscus bases pressure sensing offers several advantages over other MEMS technologies for certain applications. These advantages include the potential for smaller footprints, harsh environment survivability, simple CMOS integration, and ease of fabrication. The pressure sensors can be realized in a variety of substrates because innumerable fabrication techniques have been demonstrated to create microfluidic channels for all manner of form and function. The small effective hydraulic diameter of these channels can be exploited to produce gas/liquid interfaces that create menisci that be used to trap gas in sealed chambers. The pressure is monitored by optically or electronically measuring the displacement of the meniscus which behaves according to the gas laws. This paper reports on the theory and realization of several fundamental concepts for this type of sensor including; auto-calibration of meniscus forces regardless of sensor material or liquid, electrode integration for electronic interrogation, simple repeatable manufacturing, and long-term drift. Hundreds of sensor devices were fabricated from Silicon and glass and demonstrated positive pressure sensitivities of 42.5 µm/kPa around atmosphere. Index Terms- Capacitive sensing, Microfabrication, Microfluidics, Pressure sensors.