Publications

Integrated Molecular Diagnostic Platform

Byungrae Cho
Luke P. Lee
Ming C. Wu
Randall J. Lee
2017

Infectious and non-communicable diseases impose a global burden of health on both developing and developed countries despite technological advancements in medicine and healthcare. In this perspective, point-of-care testing (POCT) has been paid attention as an area with enormous potential to solve this problem. Point-of- care molecular diagnostic enables to provide diagnoses from clinical samples to clinicians without wasting time such as sample transporting or sample preprocessing. However, most of nucleic acid diagnostics still are performed in central health facilities because they...

Instrumenting Flexible Substrates for Clinical Diagnosis and Monitoring

Amy Liao
Michel M. Maharbiz
2018

Over the past decade, there has been rapidly growing interest in wearable and implantable devices for a wide range of biomedical applications. For many applications involving prolonged contact with the body, devices that are compliant and can comfortably conform to and move with the patient are highly preferred. These flexible substrates (i.e. clothing, bandages, meshes, catheters, etc) can be instrumented to measure various physiological markers, such as temperature, pH, and oxygenation levels, to better inform clinical care. In this dissertation, I will discuss two examples of...

Piezoelectric Micromachined Ultrasonic Transducers for Ultrasonic Fingerprint Sensors

Joy (Xiaoyue) Jiang
David A. Horsley
Liwei Lin
Bernhard E. Boser
George C. Johnson
2018

A variety of physical mechanisms have been exploited to capture electronic images of a human fingerprint, including optical, capacitive, pressure, and acoustic mechanisms. Compared to other technologies, ultrasonic fingerprint sensors have two major advantages (1) they are insensitive to contamination and moisture on the finger (2) they have the ability to measure images at multiple depths hundreds of microns from the sensor surface. With the maturity of the thin film piezoelectric materials technology and MEMS-CMOS eutectic wafer-bonding process, piezoelectric micromachined...

Ring-shaped and Dual-electrode Bimorph Piezoelectric Micromachined Ultrasonic Transducers

Benjamin Eovino
Liwei Lin
Tsu-Jae King Liu
George C. Johnson
2018

The potential widespread usages of ultrasonic transducer technology have inspired the development of microelectromechanical systems (MEMS)-based devices. The research presented in this dissertation focuses on enhancing the performance of piezoelectric micromachined ultrasonic transducers (PMUTs) by devising innovative design structures, analytically deriving models to understand and optimize performance, and using these findings to demonstrate PMUT-based systems with increased capabilities. The ring-shaped PMUT is firstly introduced as a high-performance PMUT architecture, which is...

Large, Ordered 3D Nanocup Arrays for Plasmonic Applications

Joanne Lo
David A. Horsley
Jack L. Skinner
2010

A large, ordered nanocup array was fabricated and optically characterized. A novel fabrication method that combined Nanoimprint lithography (NIL), soft lithography, and shadow evaporation was designed to create asymmetric nanoparticles in a large (0.5cm x 1cm) array with subwavelength features. Although this fabrication procedure can be used to create many different types of asymmetric nanostructures that are useful in various plasmonic applications, here we fabricated a periodic nanocup array...

Silicon Electromechanical Microgrippers: Design, Fabrication, and Testing

Chang-Jin Kim
Albert P. Pisano
Richard S. Muller
1991
Microgrippers with jaw spans of l0um have been made from thin films (2um thick) of polycrystalline silicon (polysilicon) by using micromachining technology derived from IC-manufacturing methods. A 500um-long, on-wafer gripper, electrostatically driven by flexible-comb actuators, has been designed, fabricated,...

Impact Actuation of Polysilicon Micromechanical Structures

Abraham Lee
Albert P. Pisano
Roger T. Howe
1992
Impact on silicon? One may have the experience in dropping a silicon wafer on the floor, and shattering it to pieces. Or trying to dice a wafer by a diamond marker, and accidentally crunching the edges. These experiences may lead...

Controlled Structure Release for Silicon Surface Micromachining

David Monk
David S. Soane
Roger T. Howe
David B. Graves
1993
Silicon surface micromachining is a new technology that uses many of the common microfabrication techniques found in silicon integrated circuit (IC) production. The key processing step that is the sacrificial layer etch for releasing microstructures which is not ...

Micromechanical Investigations of Silicon and Ni-Ti-Cu Thin Films

Peter Krulevitch
George C. Johnson
Roger T. Howe
Kyriakos Kornvopoulos
1994
Residual stress, microstructure, and mechanical properties of low pressure chem cal vapor deposited polycrystalline silicon (undoped and phosphorus doped), selectively grown homoepitaxial silicon, and shape memory Ni-Ti-Cu films are investigated. Different methods...

Micromachined Piezoelectric Cantilever Transducers

Seung Lee
Richard M. White
George C. Johnson
Fai Ma
David S. Soane
1995
In this thesis, we present a micromachined piezoelectric acoustic transducer fabricated on a cantilever. Use of the cantilever as a supporting diaphragm produces a highly sensitive microphone. In addition, when the device is driven electrically as an output transducer (microspeaker), the relatively large...