Publications

FEA-Assisted Analysis and Gain Optimization of a Micromechanical Resonant Displacement Amplifier

Gleb Melnikov
Clark T.-C. Nguyen
Kristofer S.J. Pister
2017

Micromechanical resonant switches have the potential to greatly outperform currently dominant semiconductor switches due to their higher figures of merit. Of the current designs available, resonant MEMS switches are among the most promising, as they can achieve very large amplitudes at resonance with greatly reduced actuation voltages compared to more conventional MEMS switches, such as those that rely on pull-in based actuation.

Such resonant micromechanical devices are currently in their infancy, and require additional optimization and analysis to resolve their...

Finite Element Analysis of the Effects of Package Induced Stress on Micromechanical Resonator Temperature Stability

Divya Kashyap
Clark T.-C. Nguyen
Liwei Lin
2015

Vacuum encapsulation of RF disk and beam resonators is often needed to maintain high quality factor and frequency stability. Conventionally, this is performed at the wafer level by anodic, eutectic, fusion, or glass frit bonding. After wafer dicing, packaging proceeds with die attach to the package substrate and plastic over molding. This process leads to many contacts between materials of different coefficients of thermal expansion (CTE) resulting in package-induced stress. The focus of this work is to determine the effect of this stress on the temperature stability of...

Dosimetry Dust: An Ultrasonic Backscatter Implantable Dosimetry Device

Stefanie Garcia
Michel M. Maharbiz
Kristofer S.J. Pister
2017

Proton beam therapy is a well-established medical procedure for treating certain kinds of cancer, and is uniquely suited for treatment of head, neck, and eye tumors. Despite the continuous improvements in medical physics treatment plan simulations, improper tissue irradiation can easily occur if there is a shift in the tumor and/or critical organs during the irradiation process. A fully implantable dosimeter for in vivo dose measurements can provide closed loop treatment feedback to a physician during radiation treatments, and assist in enabling full irradiation of a tumor. This work...

A High-Resolution Resonant MEMS Strain Gauge

Mark Wolfson
Albert P. Pisano
Roger T. Howe
Oliver M. O'Reiily
2000

An investigation into the development of a high-resolution micro-strain gauge is discussed here. The design presented is a resonant sensor in the form of a double-ended tuning fork (DETF) that employs MEMS technology to achieve maximum sensitivity at...

An Investigation of MEMS Anchor Design for Optimal Stiffness and Damping

Daniel Sherman
Albert P. Pisano
George C. Johnson
Panayiotis Papadopoulos
1996

Micro-resonators for use in accelerometer applications and polysilicon flexures designed to damp unwanted vibrations of a micro-positioner are two examples of Micro-Electro-Mechanical Systems (MEMS) that require optimal anchor stiffness and damping properties. This investigation sought to determine how the geometric...

Fabrication and Assembly of a 2.4mm Compressed Gas Rotary Expander

Jose Rosario-Rosario
Albert P. Pisano
Dorian Liepmann
2005
A 2.4 mm-scale rotary engine has been redesigned, fabricated and partially assembled to operate as a compressed gas expander. The micro-expander is a multilayered stack of bonded components that are fabricated from single crystal silicon using bulk micro-machining techniques. This research is a continuation from previous work initiated by the MEMS Rotary Engine Power System (REPS) research group at UC Berkeley. The goal of the MEMS REPS project is to develop...

Fabrication and Assembly of A 2.4mm Compressed Gas Rotary Expander

Jose Rosario-Rosario
Albert P. Pisano
Dorian Liepmann
2005
A 2.4 mm-scale rotary engine has been redesigned, fabricated and partially assembled to operate as a compressed gas expander. The micro-expander is a multilayered stack of bonded components that are fabricated from single crystal silicon using bulk micro-machining techniques. This research is a continuation from previous work initiated by the MEMS Rotary...

Ultra High Frequency Piezoelectric Resonators: Suspension and Elastic Coupling

James Porter
Albert P. Pisano
Roger T. Howe
Liwei Lin
2004

In this research project, the suspension and elastic coupling of Film Bulk AcousticResonators (FBAR) has been investigated. Individual resonators and small arrays of AlN FBARs have been designed and fabricated in a post-CMOS compatible process. Suspensions based on networks of thin beams did not perform well, but m...

MEMS Based Capillary Pumped Loops for Integral Thermal Management

Kip Pettigrew
Dorian Liepmann
Luke P. Lee
Ralph Grief
2002

In continuation of the work performed on the micro-capillary pumped loop (CPL), a Micro Electro Mechanical Systems (MEMS) based CPL was designed built and tested to remove heat over a 1 cm2 ...

Characterization of Low-Fluence Excimer Laser Annealing of AlN Thin Films

David Park
Albert P. Pisano
2005

A process for laser annealing aluminum nitride (AlN) thin films with a low-fluence excimer laser has been characterized. Residual stress inherited during film deposition can cause undesirable effects, such as delamination and cracking, in MEMS devices. Current methods of furnace annealing require 30 minutes or longer, but laser annealing can reduce this anneal time down to less than 1 minute. This makes laser annealing a valuable time saving tool in the fabrication process of MEMS devices.

The laser used in this study was a 40 ns KrF excimer laser with a 248 nm...