Electrostatic Microactuator Design Using Surface Acoustic Wave Devices

Abstract

An integration of low power operated Surface Acoustic Wave (SAW) devices with the electrostatic microactuators for microfluidic and similar applications is presented in this chapter. Passive, low power, and small area devices can be interrogated wirelessly using SAW devices, which can respond to a uniquely coded signal for a secure and reliable operation. The novel approach relies on converting the interrogating coded signal to surface acoustic wave that is then correlated with an embedded code. A theoretical analysis of how the actuation mechanism operates is carried out and simulation results of the new microactuator are discussed. At the initial analytical stage, for simplicity, a basic SAW delay line structure is used to generate an electrostatic field between output interdigital transducer (IDT) of the SAW device and a thin conductive plate (actuator), which is placed on top of the output IDT. The static and transient displacement analysis of the actuator is carried out using ANSYS simulation tools. A comparison between the static displacements obtained from ANSYS based simulations and Rayleigh-Ritz based analysis is also presented and discussed.

Finite element modelling of surface acoustic wave device based corrugated microdiaphragms

“…This analysis is an extended version of the authors' previous work [20], which was developed to analyse the performance of a SAW device based electrostatic actuator using the Rayleigh-Ritz method. Here, an energy minimization technique is used to solve the problem for the corrugated diaphragm model.…”

“…In the authors' previous work [19,20], the electric potential at the output IDT region was found to be a combination of the electric potential at the IDT fingers and the electric potential at the IDT finger gaps, and this is shown in equation (2). where…”

Wireless microfluidic control with integrated shape-memory-alloy actuators operated by field frequency modulation

“…Passive actuation mechanisms eliminate the need for active circuitry and batteries and are thus potentially advantageous in terms of size, longevity, cost and robustness of the devices. Passively operated wireless microactuators have been reported to use several mechanisms, including electrostatic actuations induced by surface acoustic waves [12] and magnetic fields [13], magnetic actuations [14][15][16][17], energy-beam-assisted heating (for shape-memory alloys (SMA) [18][19][20][21] and bimorph [22][23][24]). However, they pose various practical issues such as small actuation force and stroke, use of high voltages, micromachining and integration of ferromagnetic materials, and actuator/system packaging.…”