Graduation Year

2005

Document Type

Thesis

Degree

M.S.E.E.

Degree Granting Department

Electrical Engineering

Major Professor

Shekhar Bhansali, Ph.D.

Committee Member

Tom Weller, Ph.D.

Committee Member

John Bumgarner, Ph.D.

Committee Member

Scott Samson, Ph.D.

Keywords

FPW, PZT, Fabrication process, Sol-gel deposition, Piezoelectricity

Abstract

Current MEMS development is driven by the need to develop various 'Miniaturized Total Chemical Analysis Systems ([mu]TAS), biological and chemical sensing, drug delivery, molecular separation, microfiltration, amplification, and sequencing systems. In this work, the use of flexural plate wave devices as an actuator has been investigated.

This research was done with the aim of developing a platform to build FPW devices for use in System-On-Chip applications. It is well known that acoustic forces generated by a flexural plate wave (FPW) device can cause fluid motion, by the principle of acoustic streaming. Also the proven ability of FPW devices to cause mixing, filtration and to work as a chemical-biological sensor can be used towards building a micromachined [mu]TAS.

The effects of the IDT finger width, spacing, aperture, membrane thickness, and driving conditions on the device performance was studied to understand the impact of IDT design on device performance. For this research bidirectional IDT’s were used, and at a later stage unidirectional IDT’s on one end and bidirectional IDT’s on the other end can be used for devices that need to function both as a pump and as a sensor.

The devices were tested under various conditions to understand the device performance. The devices were tested with and without a ground. The device performance was also studied when operated under the poling condition. Also the response of the device was tested before and after etching the membrane and a significant improvement in the output response was observed with the reduction in the transmission loss.

The FPW device performance was studied and it is observed that uniformly spaced IDT’s which have an acoustic path of at least 25 wavelengths long are required for good device performance. It is also observed that the devices need to be isolated from one another piezoelectrically for better device performance.

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