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Current Research

I lead the Quantum Energy Systems (QES) side of the group within the Berkeley Micromechanical Analysis and Design Group (BMAD). The research of QES is focused on four key areas:

(1) Thermal Management and Energy Scavenging
(2) Nanomanufacturing systems
(3) Bioinspired materials systems and their applications
(4) MEMS tools for Biology and Medicine

My research team consists of several graduate and undergraduate student researchers who perform applied research sponsored by both federal grants and industry. A few our current projects and my dissertation research are listed below:

Passive, micro-cooling thermal ground plane system

Thermal management of high power density electronics is an essential, enabling technology for next generation electronic systems. Phase change is the preferred choice for heat transport solutions because of the ability to absorb large heat fluxes through latent heat. Current technology uses macro-scale capillary driven systems such as Loop Heat Pipes (LHP) and thermosyphons, which are passive devices that have proved to be efficient and reliable. However, these devices do not allow for chip-level integration and do not scale well for future (and even current cutting-edge high-performance) electronic requirements. The goal of the microColumnated Loop Heat Pipe (cLHP) project is to develop a "thermal ground plane" (analogous to an electronic ground plane) which is a uniform, isothermal substrate for transporting heat away from high power density electronic devices.

For more information, please visit the corresponding project pages at:
Berkeley Micromechanical Analysis and Design Group
Berkeley Sensor and Actuator Center

Novel templates and microfluidic molding for roll-to-roll processes

With the extremely large costs for cutting edge microfabrication facilities and the increasing need for energy efficiency in processes to lower manufacturing costs, many are turning to roll-to-roll processes utilizing templated printing techniques such as gravure as a possible solution for fabrication of micro/nanoelectronics. While new inks and their rheologies as well as novel substrate have been introduced to the mix to enable roll-to-roll processes, one of the major components have been overlooked: the templates themselves. For robust and repetitive manufacture of devices using the templates, the templates need to be (1) rigid, (2) vapor permeable, (3) alignable and (4) chemically resistant. My colleagues and I have found ideal candidates in a family of rigid, vapor permeable polymers synthesized originally for the oil and gas industry, which we have engineered into template materials for microfluidic molding and imprinting processes. The results are well-defined features in all three dimensions on par with current photolithography techniques which do not suffer from the fluidic limitations of other currently existing methods. The templates are also transparent allowing for standard optical alignment which is key to multi-layer processing.

For more information, please visit the corresponding project pages at:
Berkeley Micromechanical Analysis and Design Group
Berkeley Sensor and Actuator Center

Online, microfluidic reactors

By using microfluidic reactors which separate nucleation and growth of nanomaterials confined in droplets, highly monodisperse particles can be synthesized. By adding in quality control through electron microscopy in real-time, we take the concept further providing closed-loop control which allows for dialing in the correct flow rates of the chemicals along with proper, focused temperature control to ensure energy efficient, continuous manufacture of nanomaterials.

For more information, please visit the corresponding project pages at:
Berkeley Micromechanical Analysis and Design Group
Berkeley Sensor and Actuator Center

Dissertation: Biomimetic, Polymeric Transistor-based Biosensor Technology

The goal of this research is the creation of robust, flexible, polymer sensors and circuits fabricated from the polysaccharide, chitosan. The sensors will detect diatomic gases and DNA to more complex macro molecules (e.g. exotoxins) in a fluidic or dry environment. Polymer-nanoparticle (ex. CdS) hybrid films allow for development of robust, polymer thin-film transistors and, with optimization of the hybrid film, sensitive photodetectors. These transistors will be developed into gas or chemical sensors through functionalization of the polymer active layer or dielectric with proteins specific to a target analyte. This technology will enable the development of integrated polymer sensors and electronics which are low-cost, robust and highly versatile due to the replacement of semiconductor, dielectric and possibly metal layers with polymers and minimal thermal budget.

For more information, please view the archived file provided by EECS at UCB here.

Last updated on: October 7, 2011
©2005 Jim Cheng

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