Device Physics and Material Properties of Two-Dimensional Semiconductors

Sujay Desai
Ali Javey
Junqiao Wu
Tsu-Jae King Liu
Jeffrey Bokor

Device architecture and materials innovations have enabled transistor scaling for the last several decades, boosting the performance of electronics, increasing the speed of communication and computational systems, lowering power consumption and reducing costs per operation. Two-dimensional (2D) materials have gained tremendous attention in the last decade, after the discovery of graphene which has exceptional properties like high carrier mobility, ultra-thin van der Waals connected layers (~ 0.3 nm thick), high tensile strength, etc.

Transition metal...

Transparent Micro-electrocorticography (μECoG) Arrays for Optogenetic Mapping of Surface Potentials

Brian Pepin
Michel M. Maharbiz

Electrocorticography (ECoG) has been used for decades clinically to help localize epileptic seizures but has only recently come into vogue as a potentially useful imaging modality. This change has partially been driven by the development of new micro-electrocorticography (µECoG) arrays which take advantage of modern surface micromachining techniques to achieve extremely dense electrode arrays packed with tiny (less than500µm diameter) electrodes. As an imaging tool, µECoG may be improved by taking advantage of the transparent µECoG array technology developed at the University of...

Parametric Oscillation with Wineglass Disk Resonators

Thanh-Phong Nguyen
Clark T.-C. Nguyen
Bernhard E. Boser

Parametric oscillation provides another avenue to excite micro electro-mechanical resonators into oscillation. Rather than driving the resonator at its resonant frequency, modulating the stiffness of the resonator forces this motion. While this technique can lead to failures, it also can provide methods for frequency division, phase noise reduction, and sustaining oscillations of various frequency with a single amplifier. This work models the voltage conditions for parametric oscillation and compares them to measured results with an accuracy of 15%. Discrepancies caused by...

Design and User Guide for the Single Chip Mote Digital System

Sahar Mesri
Kristofer S.J. Pister
Ali M. Niknejad

In order to create a low-power and lightweight wireless sensor node for the control of MEMS microrobots, the Single Chip Mote project aspires to integrate a fully-functioning microprocessor, radio, sensors, and solar cells onto a single die, while also eliminating the need for external components through careful architectural design. This report presents the past two years of work on the design of the Single Chip Mote digital system, complete with an ARM Cortex-M0 microprocessor, control logic for an IEEE 802.15.4 radio, special-purpose radio timers, and ADC interface. This includes...

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

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

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

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

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

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

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
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...