Design of MEMS-Based Tunable Antennas, Organic Transistors and MEMS-Based Organic Control Circuits

Abstract

The advent of precision three-dimensional micromachining technologies in the last couple of decades has seen the birth of an exciting and potentially revolutionary field called Microelectromechanical Systems (MEMS). Predictions about the far-reaching implications and widespread prevalence of such miniaturized, smart, integrated systems and sub-systems have been made and yet as of today only modest market presence and commercial success has been attained. Having arisen out of the silicon IC microfabrication technology in academic and research environment, the initial developments in MEMS were driven mainly by technical curiosity and demonstrability. Like in any emerging field, most of the developments have therefore been an array of new fabrication techniques, new materials, and new device structures for a host of sensor and actuator applications. However, the commercial viability and success of MEMS devices in the industrial and academic communities require tackling some of the daunting technical and commercialization issues impeding the market presence of such systems. This dissertation explores two varied and vital applications of MEMS devices. One application involves the development of MEMS-based tunable antennas and the other explores the integration of MEMS sensors with organic transistors. Tunable antennas are drawing interest because instead of having multiple antennas switched into multiple transceiver chains covering different frequency ranges, a single multi-band tunable antenna assembly would provide size advantages and minimize product packaging complexity. This dissertation demonstrates a coplanar patch antenna made tunable by the use of a MEMS varactor. The second application explored was to develop a ‘Polymer Microsystem’ by the integration of a Polymer MEMS device and Organic Electronics. Traditionally, microsystems have been fabricated using silicon-like semiconductor substrates by micromachining techniques. Silicon (or thin-film in general) may be the ideal substrates for semiconductor devices, but they may not be suitable for all microsystem applications. In particular, silicon based wafer level technology may not be suitable for cost effective manufacturing and packaging of microsystems for large area and large volume applications. The proposed work was to demonstrate a plastic microsystem using low cost fabrication techniques. As a proof-of-concept of the proposed plastic microsystem, this project demonstrated the integration of a Polymer MEMS pressure sensor with an organic field effect transistor.