Richard M. White (Advisor)

Biochemical Microflow System / Microfabricated Optical Chopper

Michael T. Ching
Richard M. White
Albert P. Pisano

The application of micromechanics to biochemical instrumentation yields many improvements in size, efficiency, and power consumption. The microdevices have small volumes which are compatible with many biochemical reactions. With the addition of integrated sensors, ...

A Silicon-Based Microsensor to Measure Airborne Contaminants

Bharat M. Shah
Richard M. White
Albert P. Pisano

In this reseach project the ability of a microfabricated acoustic-wave microsensor to detect volatile organic compounds in indoor air was studied. The microsensors were made in the Berkeley Microfabrication facility following designs developed at the Berkeley Sensor & Actuator Center. The devices were exposed in a four-liter chamber to vapor-phase concentrations of six representative VOCs one at a time: tetrachloroethylene, 1,1,1-trichloroethane, toluene, benzene, ethanol, and formaldehyde. The device sesnitivity to each VOC was computed from the measured oscillator frequency and...

A MEMS Sensor for AC Electric Current

Eli Sidney Leland
Paul K. Wright
Richard M. White
Dennis K. Lieu
This manuscript describes the development of a new MEMS sensor for the measurement of AC electric current. The sensor is comprised of a MEMS piezoelectric cantilever with a microscale permanent magnet mounted to the cantilever’s free end. When placed near a wire carrying AC current, the magnet couples to the oscillating magnetic field surrounding the wire, causing the cantilever to deflect, and piezoelectric coupling produces a sinusoidal voltage proportional to the current in the wire. The sensor is itself...

Microstructure Micropackaging

Kristen M. McNair
Roger T. Howe
Richard M. White

Two processes are developed to fabricate electrostatic comb drives hermetically encapsualted in a silicon nitride or polysilicon micropackage. To fabricate the silicon nitride micropackage, high-doped phosphosilicate glass is deposited, after the electrostatic comb-drive process is complete except for the release etch, and reflowed to form a mould for the silicon nitride microshell. The mould is patterned with a 5:1 BHF wet etch, and then the etch channel layer of phosphosilicate glass is deposited and patterned with a wt etch. The silicon nitride microshell layer is depositied, and holes...

Biological Applications of Micromachined Ultrasonic Flexural Plate-Wave Technology

Audra Hsien-I Meng
Richard M. White
Rajendra Bhatnagar
Albert P. Pisano
The micromachined acoustic flexural plate-wave (FPW) device has many applications in biological research and medical diagnostics. In order to safely use the FPW device for these applications, we studied the effects of ultrasound produced with the device on biological...

The Development of Lead Zirconate Titanate Thin Films for Piezoelectric Microactuators

Annabel Susan Nickles
Eugene E. Haller
Richard M. White
Timothy D. Sands
Piezoelectric actuation of a thin film is one means used for electrical-mechanical transduction in Microelectromechanical systems (MEMS). Currently, the most commonly employed piezoelectric thin-film material is ZnO. Replacing ZnO with certain compositions of lead zirconate titanate (PZT)...

Control of Fluids in Microscale Devices

Michael James DeBar
Dorian Liepmann
Albert P. Pisano
Richard M. White
Pumping in microdevices due to gradients in surface tension was investigated both theoretically and experimentally. When a gradient in surface tension exists along an interface between two fluids, there is a net motion of the interface. The...

Sputter Deposition of Piezoelectric Lead Zirconate Titanate Thin Films for Use in MEMS Sensors and Actuators

Clifford Frederick Knollenberg
Timothy D. Sands
Richard M. White
Eugene, E. Haller
This thesis describes the development of sputter-deposited piezoelectric lead zirconate titanate for sensing and actuation in microelectromechanical systems (MEMS). Piezoelectricity, the coupling of mechanical stress or strain and electric polarization observed in certain dielectric ceramics, is attractive for converting between electrical and mechanical energy in MEMS devices. While piezoelectric ZnO is currently used in MEMS devices such as the flexural plate wave device (FPW), replacing this layer with...

Batch-Fabricated Ferromagnetic Microactuators with Silicon Flexures

Jack William Judy
Richard S. Muller
Richard M. White
Timothy D. Sands
This manuscript investigates the use of magnetism and ferromagnetic materials in microelectromechanical systems (MEMS) and describes ways to integrate ferromagnetic materials with conventional silicon-based surface micromachining. Surface-microma-chined, batch-fabricated structures that combine plated-nickel and nickel-iron films with polysilicon mechanical flexures, are studied. The microstructures are constructed in a batch-fabrication process that uses electroplating and conventional lithography, materials,...