Publications

Bubble-Actuated Planar Microvalves

Alexandros Papavasiliou
Albert P. Pisano
Dorian Liepmann
Luke P. Lee
2001

This work describes the development of low-power bubble-actuated planar micro gate valves. The work includes the design of the gate valve, the development of electrolysis bubbles as a low power actuator, and a novel fabrication procedure that allows these valves to be integrated with other planar fluidic devices and controlling circuitry. The operation of the valves is demonstrated and valve performance is measured in terms of leakage, power consumption, and cycle time.

The low-power, bubble-actuated, planar micro gate valves consist of a silicon gate that is thrust across a...

Hybrid Surface-/Bulk-Micromachining Processes for Scanning Micro-Optical Components

Jocelyn Nee
Kam Y. Lau
Richard S. Muller
Paul Wright
2001

This dissertation discusses the design and fabrication of micro-optical scanners that have high-quality optical-surface properties and are capable of previously unattainable high scanning rates. Scanners having high-quality optical surfaces are fabricated and characterized in both diffractive and reflective applications.

A first project investigates methods of creating scanning rectangular diffraction gratings using well-established fabrication methods of silicon surface-micromachining in a foundry process. We then introduce new methods to form an actuated blazed grating, a...

Polycrystalline Silicon Germanium for Fabrication, Release, and Packaging of Microelectromechanical Systems

John Heck
Roger T. Howe
Tsu-Jae King
George Johnson
2001
Polycrystalline silicon germanium has recently proven to be a compelling alternative to polysilicon for micromachining. Low temperature fabrication of micromechanical structures is possible, which enables their modular integration with conventional electronics. The deposition and crystallization temperatures are significantly lower than for polysilicon, and low-stress, low-resistivity structural films can be achieved with little or no annealing. Poly-Ge can be used as a hydrogen peroxide-soluble sacrificial layer, so a...

Mechanical Analysis and Design of Vibratory Micromachined Gyroscopes

Wyatt Davis
Albert P. Pisano
Oliver M. O'Reilly
Kristofer S.J. Pister
2001
Vibratory micromachined gyroscopes typically exhibit certain undesirable behaviors that impede the angular rate measurement, such as nonlinearity, cross-axis sensitivity, scale factor offset, and quadrature error. These errors have sources in both the mechanical and electrical ...

Effect of Devitrification Temperature on the Microstructure of NiTi Films

Michael Vestel
Ronald Gronsky
Albert P. Pisano
2002

Crystalline nickel titanium (NiTi) films are known to possess superelastic properties offering superior advantages in engineering applications where resilient mechanical response is essential. One such application of increasing importance in the biomedical field is the fabrication of micro-needles for transdermal or subdermal fluid transport, including the integration of micro-needles with silicon structures such as bio-MEMS assemblies. Unfortunately, the direct deposition of Ni-Ti alloys onto silicon is sometimes compromised by grossly mismatched thermal expansion coefficients...

Design and Modeling of a Dual Mass SOI-MEMS Gyroscope

Ashwin Seshia
Roger T. Howe
Kristofer S.J. Pister
1999

This report discusses the design of a dual mass silicon-on-insulator(SOI) MEMS gyroscope. The main advantage of the dual mass gyroscope is the ability to cancel out common mode acceleration. The SOI MEMS process also provides several inherent advantages including increased out-of-plane stiffness, increased mass, and increased...

Integrated Micromechanical Resonant Sensors for Inertial Measurement Systems

Ashwin Seshia
Roger T. Howe
Bernhard E. Boser
Kristofer S.J. Pister
Roberto Horowitz
2002
Thumbnail-sized inertial measurement systems based on Micro Electro Mechanical Systems (MEMS) technology have been perceived as a breakthrough in the field of inertial navigation. However, even as micromechanical accelerometers have seen widespread commercialization, vibratory micromechanical gyroscopes...

Assembly and Molding Processes for Three-Dimensional Microfabrication

Elliot Hui
Roger T. Howe
Kristofer S.J. Pister
Dorian Liepmann
2002
Lithographic semiconductor microfabrication has been employed with great success for the manufacture of mechanical structures, achieving microscopic dimensions and great complexity at low cost. However, due to the inherently planar nature of the lithographic process, this technology is limited in its capability to produce three-dimensional structures. In this work, three strategies are presented for extending thin-film microfabrication into the...

Ultrasonic Microdevices for Integrated On-Chip Biological Sample Processing

George Dougherty
Timothy Sands
Eugene Haller
Albert P. Pisano
2002
Integrated lab-on-a-chip devices, also known as micro total analysis systems (p-TAS), are expected to play a leading role in biological research and medicine in the 21st century, and on chip sample processing is a key function of...

A Magnetically Actuated Scanning Microplatform for Intravascular Ultrasound Imaging

Carl Chang
Richard S. Muller
1998

A magnetically actuated microplatform for use in invivo instrumentation applications is described. A specific embodiment for an intravascular ultrasound imaging system is the focus of this research. Magnetic microactuators with the ability to carry ultrasound transducer elements while in a liquid have been demonstrated. These actuators have also shown the ability to rotate the required angular range (+/-45) within the specified magnetic field limits (less than 150...