Publications

IC-Processed Polysilicon Micromechanics: Technology, Material, and Devices

Yu-Chong Tai
Richard S. Muller
Roger T. Howe
1989
Movable pin joints, gears, springs, cranks, and slider structures with dimensions measured in micrometers have been fabricated using silicon microfabrication technology. These micromechanical structures, which have important transducer applications, are batch-...

Micromachined Resonant Electrometer

Patrick Riehl
Richard S. Muller
Roger T. Howe
1999

Numerous analytical instruments require a sensor to detect small quantities of electric charge. The techniques of scanning tunneling microscopy and ballistic electron emission microscopy require tiny currents to be sensed, on the order of a few picoamperes. In a mass spectrometer, the analysis of a sample requires a measurement of the current resulting from ions passing through a mass filter. In a technique known as chargedetection mass spectrometry, used to measure the mass of large molecules such as DNA molecules or virus particles, the resolution of the mass determination is limited in...

Microsystems for Electrostatic Sensing

Patrick Riehl
Richard S. Muller
2002

We have developed highly sensitive electrometers and electrostatic fieldmeters (EFMs) that make use of micromechanical variable capacitors. Our systems operate using the same basic principle as a chopper-stabilized amplifier or vibrating-reed electrometer. We use micromechanical resonators with specialized electrodes that implement variable capacitors. Modulating the input capacitance of the sensor generates an ac sense voltage proportional to the input charge or field that is detected using a lock-in amplifier. If the motional frequency is sufficiently high, 1/f noise does not...

Micromirror Arrays for Adaptive Optics

Michael Helmbrecht
Richard S. Muller
2002

Deformable mirrors (DM) shape the wavefront of an optical beam in adaptive-optics (AO) systems. The ability to manipulate wavefront phase quickly allows for real-time correction of aberrated wavefronts. We investigate the design of a micromachined, segmented, highstroke deformable-mirror array for AO.

To achieve large mirror stroke, polysilicon-nickel bimorph flexures are designed to quiescently elevate surface-micromachined mirror platforms roughly 20 µm above underlying electrodes as a result of tuned residual stresses in the bimorph materials. We control stress in the...

Thermal and Electrostatic Microactuators

Robert Conant
Richard S. Muller
2000

This dissertation discusses the fundamental limits of scanning mirror design, focusing on the limitations due to the interaction between mechanical properties
(mirror flatness and dynamic deformation), and optical properties (beam divergence and optical resolution). The performance criteria for both resonant scanning mirrors and steady-state, beampositioning mirrors are related to the mirror geometries, desired optical resolution, material properties, and mechanical resonant frequencies. The optical resolution of the scanning mirror is linearly dependent on the mirror length, so longer...

Micromachined Mirrors

Robert Conant
Richard S. Muller
Kristofer S. J. Pister
Liwei Lin
2002

This dissertation discusses the fundamental limits of scanning mirror design, focusing on the limitations due to the interaction between mechanical properties (mirror flatness and dynamic deformation), and optical properties (beam divergence and optical resolution). The performance criteria for both resonant-scanning mirrors and steady-state, beam-positioning mirrors are related to the mirror geometries, desired optical resolution, material properties, and mechanical resonant frequencies. The optical resolution of the scanning mirror is linearly dependent on the mirror length, so longer...

Microfiltration and Flexural Plate Wave Devices

Pamela Caton
Richard M. White
2001

Current MEMS microfilter improvement is driven by the need to perform absolute separation of micron-sized particles from milliliter-scale uid volumes. Such filtration is an essential step in many biological and medical applications. For example, routine blood tests require separating blood plasma from whole blood. Using microfabrication techniques it has recently become possible to create integrated miniaturized fluid-handling devices. Promising applications include miniaturized systems for the filtration, fractionation, and manipulation of biological cells and DNA. Before such promise can...

MEMS-Based System for Particle Exposure Assessment Using Thin-Film Bulk Acoustic Wave Resonators and IR/UV Optical Discrimination

Justin Black
Richard M. White
2006

Airborne particulates are responsible for severe adverse effects on human health, examples being the lung disease caused by tobacco smoke and severeasthmatic reactions to certain other particulates. Present instrumentation to measure such particulates is bulky, costly to purchase, and difficult to operate; its use in field studies usually requires sending samples collected to an analytical laboratory in order to identify the particulates. This dissertation describes a...

Micromachined Silicon Ultrasonic Longitudinal Mode Actuators: Theory and Applications to Surgery, Pumping, and Atomization

Amit Lal
Richard M. White
1996
A silicon-based high-intensity ultrasound actuator technology is developed. It is shown that silicon's high maximum ultrasonic particle velocity, high thermal conductivity, and low internal loss, make it an ideal resonator material for high-intensity ultrasonic actuators. Furthermore, it is expected that silicon micromachined batch...

A Micromachined Acoustic Immunosensor for the Detection of Breast Cancer Antigens

Amy Wang
Richard M. White
1997
We have developed an acoustic immunoassay that couples a mass-amplifying label with a silicon-micromachined gravimetric sensor, the Flexural Plate Wave (FPW) device. This assay has direct application to the diagnostic detection of a breast cancer antigen in the sera...