Dorian Liepmann (Advisor)

Research Advised by Professor Dorian Liepmann

Stability, Sensitivity, and Selectivity of Graphene FET-based Gas Sensors

Takeshi Hayasaka
Liwei Lin
Dorian Liepmann
Ana Claudia Arias
2019
Miniaturized gas sensors are expected to witness a high demand in the next decade invarious industry fields due to the small foot print, low power consumption, and low manufacturing cost. To date, various miniaturized gas sensors have been proposed by combining key sensing principles/materials and micro/nano fabrication technologies. Among those platforms, graphene-based gas sensor is especially promising due the unique features: gas sensing capability at room temperature, unique electrical properties, and the truly two...

Polysilicon Micromolding of Closed-Flow Passages for the Fabrication of Multifunctional Microneedles

Neil Hamilton Talbot
Albert P. Pisano
Dorian Liepmann
Richard S. Muller
1999

Three aspects of MEMS microneedle technology are developed in this work. First, a new two-wafer polysilicon micromolding process for the fabrication of multifunctional microneedles is developed. Second, microneedle strength is addressed including the investigation of strengthening methods. Lastly, the fluid-flow properties of microneedles are studied analytically and experimentally.

Polysilicon microneedles of smaller size and greater sharpness than stainless steel needles have been fabricated using a two-way polycrystalline silicon (polysilicon) micro molding process called...

Microscale Phase Change of Fuels for MEMS Power Applications

Brenda Haendler
Albert P. Pisano
Dorian Liepmann
Daniel M. Kammen
2006
As portable electronics technology advances, systems are becoming smaller and more energy intensive. While batteries are currently the only commercial power source for these applications, work is being done to create liquid fuel based portable power packs. These systems would leverage the higher energy density (W-hr/l) and specific energy (W-hr/kg) of liquid hydrocarbon fuels over available battery chemistries. For micro engines and small fuels cells there are advantages to preheating and vaporizing the fuel ...

Integrated Mesoscopic Fluidic Interconnects for Micro-Machined Fluidic Devices

Jennifer Ann Scalf
Albert P. Pisano
Dorian Liepmann
1999

An approach to fluidic interconnection which integrates a mesoscopic needle with a fluidic micro-device and which uses a membrane as a connector has been developed. This concept has been realized by the use of fusion bonding to create embedded devices within the...

Fluidic Self-Assembly of Microfabricated Parts to Substrates Using Capillary Forces

Uthara Srinivasan
Roger T. Howe
Dorian Liepmann
Susan J. Muller
Jeffery A. Reimer
2001
In this work, we present a fluidic microassembly technique which uses capillary forces to self-assemble microparts onto a substrate. We have demonstrated this technique using microfabricated silicon parts and silicon and quartz substrates....

Effects of Abrupt Changes in Microfluidic Geometry on Complex Biological Fluid Flows

Shelly Gulati
Dorian Liepmann
Susan J. Muller
Andrew J. Szeri
David Saloner
David Trebotich
2006
Direct measurement techniques are employed to quantify the kinematics of λ-DNA flows in three microfluidic components with abruptly changing geometries. Flow through these geometries subjects the fluid to large spatial gradients in velocity, leading to viscoelastic effects. The effects on DNA transport in microscale flows are significant because flow behavior may be influenced by elasticity of individual molecules,...

Articulated Mechanisms and Electrostatic Actuators for Autonomous Microrobots

Richard Yeh
Kristofer S.J. Pister
Roger T. Howe
Dorian Liepmann
2001

Enabled by advances in both integrated circuit technology and micro electromechanical systems (MEMS), the continuing miniaturization and integration of electronics, sensors, and actuators and mechanisms will make it feasible to create insect-sized autonomous microrobots. We propose to create a class of autonomous crawling microrobots the size on the order f 1cm^3 and equipped with a power source, low-power CMOS controller, sensors, wireless communications devices and motorized articulated legs. The work presented here demonstrates how articulated insect legs could be created from rigid...

A Multi-Stage Micro-Tangential Flow Filtration System for BioMEMS Applications

Patrick Pak-Ho Leung
Dorian Liepmann
Luke P. Lee
Liwei Lin
2002

The micromachining technology that emerged in the 1980s has yielded an explosion of developments of micro electromeclianica1 systems (MEMS) in the past two decades. The developments have brought lives to many miniaturized sensors and...

BPN494: Micro, Tunable, Check Valves for Surgical Applications

Daniel Cohen
2009

There are a wide variety of surgical applications where an implantable pressure-controlling valve would be an asset. We aim to identify and characterize promising valve designs for these applications, and begin to apply them to specific problems. At present, we are working with the UCSF Division of Pediatric Surgery at Parnassus to design such a valve for use in Tracheal Occlusion pre-natal surgeries.

Project end date: 08/12/09

Fluidic Microsystems Fabricated in Epoxy

Nelson Kuan
Albert P. Pisano
Dorian Liepmann
Susan J. Muller
2001
SU-8 epoxy was applied in fabricating microfluidic systems through a low-cost and robust process. The complete fabrication and packaging process is introduced in this work and further highlighted by the presentation of two application examples: a static fluidic structure design ...