| The technological advances of micro-electro-mechanical systems (MEMS) in the past two decades have been remarkable for innovations in microfluidic systems as well as automotive applications such as pressure sensors and accelerometers. MEMS flow sensing has emerged as a field of interest in microfluidics, with a variety of sensing methods being miniaturized, such as thermal anemometry, ultrasonic sensing and flow measurement based on the Coriolis effect. Coriolis sensing is particularly attractive since, unlike most other methods which provide volumetric flow information, Coriolis sensing is capable of providing a direct, true mass flow measurement. Because of this advantage, Coriolis flow sensing has engendered strong interest in developing miniature device designs, fabrication techniques, and sensitive Coriolis detection methods. Research and development efforts have been undertaken both in academia and industry to make inexpensive, highly sensitive, reliable, and appropriately packaged Coriolis solutions. One research focus has been on detection and read-out methods for Coriolis-induced signals. Piezoresistive, optical and capacitive methods have all been tried. This dissertation introduces the resonant beam as a detecting method for Coriolis mass flow sensing. Because resonant beams measure frequency changes, they can be highly sensitive, much more so than the previously tried methods. Resonant beams have been successfully demonstrated in MEMS pressure sensors and accelerometers. This work extends their application to Coriolis mass flow devices. |
