Browse Prior Art Database

Development of a microfabricated turbine-driven air bearing rig

IP.com Disclosure Number: IPCOM000128088D
Original Publication Date: 1999-Dec-31
Included in the Prior Art Database: 2005-Sep-14
Document File: 12 page(s) / 42K

Publishing Venue

Software Patent Institute

Related People

Lin, Chuang-Chia: AUTHOR [+3]

Related Documents

http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1999-45: URL

Abstract

A team at MIT has been working to develop the technology for a micro gas turbine generator that is capable of converting chemical energy from fuel into electrical power. Such a MEMS device would represent a big leap in portable power source technology, providing ten times the power and energy density of batteries at competitive costs. The major fabrication challenge of realizing this miniature gas turbine generator is to demonstrate a baseline fabrication process capable of integrating the radial-inflow turbine rotor, bearings, and gas interconnects into a small package. The rotor is a 300 pm thick, 4 millimeter diameter disk supported by a nominally 10 pm wide air journal bearing. This structure, called the micro-bearing rig, is not only a vehicle for the development of a process methodology for fabrication of freely-rotating high aspect ratio devices, but it is also a vehicle for research into micro-fabricated gas bearings and rotordynamics. The process flow involves the use of 16 masks, 9 aligned deep reactive ion etching (DRIE) steps, aligned fusion bonding of a 5 wafer stack, and laser assisted etching. The device has been successfully fabricated, and the fabrication process will be presented, together with work in instrumentation, and packaging. In order to determine the necessary tolerances for the micro bearing fabrication and to provide performance parameters, calculations were performed based on a computational fluid dynamics and a semi-empirical model. The calculations are validated through comparison to the experimental measurements. Based on the model, improvements in theist bearing design are implemented and fabricated. The increasing fabrication accuracy is reflected by constant improvement in device performance. So far, a stable speed of 296,000 rpm has been achieved. The approach taken to develop the fabrication process flow described can be applied in many areas to build devices with complicated micro-fluidic interconnects and devices with encapsulated free-moving parts. Data from the micro-thrust bearings are useful for miniature fluidic/hydraulic actuators. The micro-rotating machinery will open new opportunities for fabricating micro valves, pumps, micro-coolers, and micropropulsion devices. Thesis Supervisor: Martin A. Schmidt Title: Professor, Department of Electrical Engineering and Computer Science

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Page 1 of 12

 This record is the front matter from a document that appears on a server at MIT and is used through permission from MIT. See http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1999-45 for copyright details and for the full document in image form.

Development of a Microfabricated Turbine-Driven Air Bearing Rig

by

Chuang-Chia Lin
B.S., National Taiwan University (1990) S.M., Massachusetts Institute of Technology (1995) Submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY at the Massachusetts Institute of Technology

June 1999

SIGNATURE OF author: [[signature omitted]]

Department of Mechanical Engineering

April 15, 1999

CERTIFIED BY: [[SIGNATURE OMITTED]]

Martin A. Schmidt

Professor, Department of Electrical Engineering and Computer Science Thesis Supervisor ACCEPTED BY: [[SIGNATURE OMITTED]]

Ain A Sonin Professor, Department of Mechanical Engineering Committee Chairman ARCHIVES MASSACHUSETTS INSTITUTE OF TECHNOLOGY LIBRARIES July 12, 1999

Massachusetts Institute of Technology Page 1 Dec 31, 1999

Page 2 of 12

Development of a microfabricated turbine-driven air bearing rig

[2]

[3]

Development of a Microfabricated Turbine-Driven Air Bearing Rig

by

Chuang-Chia Lin

Submitted to the Department of Electrical Engineering and Computer Science on April 15, 1999, in Partial Fulfillment of the Requirement for the Degree of Doctor of Philosophy

ABSTRACT

A team at MIT has been working to develop the technology for a micro gas turbine generator that is capable of converting chemical energy from fuel into electrical power. Such a MEMS device would represent a big leap in portable power source technology, providing ten times the power and energy density of batteries at competitive costs.

The major fabrication challenge of realizing this miniature gas turbine generator is to demonstrate a baseline fabrication process capable of integrating the radial-inflow turbine rotor, bearings, and gas interconnects into a small package. The rotor is a 300 pm thick, 4 millimeter diameter disk supported by a nominally 10 pm wide air journal bearing. This structure, called the micro-bearing rig, is not only a vehicle for the development of a process methodology for fabrication of freely-rotating high aspect ratio devices, but it is also a vehicle for research into micro-fabricated gas bearings and rotordynamics. The process flow involves the use of 16 masks, 9 aligned deep reactive ion etching (DRIE) steps, aligned fusion bonding of a 5 wafer stack, and laser assisted etching. The device has been successfully fabricated, and the fabrication process will be presented, together with work in instrumentation, and packaging.

In order to determine the necessary tolerances for the micro bearing fabrication and to provide performance parameters, calculations were performed based on a computational fluid dynamics and a semi-empirical model. The calculations are validated through comparison to the experimental measurements....