Wireless interrogation of a micropump and analysis of corrugated micro-diaphragms

In this chapter, Surface Acoustic Wave (SAW) device based wirelessly operated, batteryless and low-powered microdiaphragm structure is investigated. These diaphragms are intended to establish the actuation mechanism for micropumps and similar flow control devices. The actuation method of the diaphragm relies on the electrostatic coupling between the diaphragm and the output Inter Digital Transducer (IDT) of the SAW device. The theory governing the SAW device based novel actuation mechanism is elaborated. A Finite Element Model (FEM) is developed and analysed using ANSYS tools. Different design methods are considered to enhance the deflection of the diaphragm for a low control voltage. As such, inclusion of different types of corrugations, and selection of different bio-compatible materials for various sections of the diaphragm are analysed. Deflection of the diaphragm is obtained as a function of the electric potential at the output IDT of the SAW device and compared with results obtained from published research. Corrugation types such as pure sinusoidal, arc sinusoidal and toroidal types are included in the analysis. Effective meshing requirements that are specific to the presented model are considered and a mesh is developed to achieve converged results. Results show that the use of corrugations around a square-shaped diaphragm with carefully chosen materials results in better performance than that of a flat diaphragm.Don W. Dissanayake, Said F. Al-Sarawi and Derek Abbot