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Research Areas

Implantable Electrode, for collecting brain neural signals. Karen Cheung.

Circuits of the Future? Crossed single-walled carbon nanotubes. Dr. Alireza Nojeh.

Micromotors and Sensors: Mechanical parts are etched in silicon. Dr. Edmond Cretu.

Research in our group is in areas:

Research projects:

Study of the Near-Surface Stress around Cu-filled and CNT-filled through silicon vias
Near-surface Stresses in Silicon around Cu-filled and CNT-filled Through Silicon Vias
The thermomechanical stress originating from the mismatch in the coefficient of thermal expansion of Cu and silicon is a serious concern on mechanical reliability and electrical variability. This project investigates the stress distribution dependence on TSVs diameters and operation temperatures using micro-Raman and COMSOL simulations, and the impact on the keep-out-zone.
The demand for multifunctional and high-performance integrated circuits and systems has necessiated three-dimensional (3D) integration with through silicon via (TSV) technology. The thermomechanical stress originating from the mismatch in the coefficient of thermal expansion of Cu and silicon is a serious concern on mechanical reliability and electrical variability.
3D integration of integrated circuits is one of the major approaches in research to increase packing density, communication bandwidth and to reduce wire length and energy consumption. Through silicon via is one of the key technology in achieving 3D integration. Cu is used to fill TSVs, which also introduce thermal mismatch stress in the surrounding Si. This project investigate stress dependence on TSV microstructure and annealing process.
This project is in collaboration with Texas Instruments. It is to systematically investigate P diffusion behavior in SiGe and SiGe:C.
Development of an Artificial Mechanical Skin Model for Microneedle Insertion Profiling
We systematically study SiGe interdiffusion: 1) we established a unified interdiffusivity model for SiGe interdiffusion under relaxed or tensile strain over the full Ge content range from experimental data and diffusion theories. 2) We will investigate the impact of compressive strain on SiGe interdiffusion in middle to high Ge range. 3) We will study how interdiffusion depends on different dopants and doping levels.
A technology for 3D printing of biological tissue constructs that will better mimic the human physiology and expedite the drug discovery process. The first stage of this work is to develop a disposable and bio-compatible droplet-on-demand (DOD) system.
High energy density, high power and long cycle life are all properties that are needed in portable energy sources, particularly for emerging electric vehicles, and multifunctional hand-held devices. We are investigating new materials for use in these electrochemical storage devices with the aim of dramatically improving all aspects of performance. We are also creating printed energy storage devices for use in smart packaging, RFIDs and the like.
The countless number of applications urged a demand for high performance micro-accelerometers, which in turn continue to gain momentum. Within that framework, one must justify the need for an approach defined by a system level performance in closed loop integration, by understanding the current performance limitations in the state-of-the-art micro-accelerometers, in research, on the market, and when employed with other electrical components.
This project aims to design a photoacoustic imaging system for prostate cancer study. Images will be acquired by using a laser to excite acoustic waves from tissues and an ultrasound transducer array to detect the acoustic waves. The photoacoustic imaging will be combined with ultrasound imaging to study prostate cancer.
Inkjet patterning of mammalian cells
In nanoscale optical devices, both the particle and the wave nature of light can play important roles. This creates new opportunities for engineering the optoelectronic properties, for instance the amount of light absorption in a device.
We are fabricating high-speed VCSELs in GaAs for 850 nm emission. Multi-wavelength VCSEL arrays are being developed. The fabrication is carried out in the AMPEL Nanofabrication Laboratory. We are currently fabricating devices based on sub-wavelength gratings (see e.g. Optics Express 2006 article).
We develop methods for thermal modulation of the widths of microchannels during operation of microfluidic devices. This allows arbitrary modulation of the channel width after device fabrication so that flow rate and flow velocity can be set independently.
This project aims at developing arrays of micromirrors with high resonance frequencies and high tilt angles in all directions. The mirrors are actuated through electrostatic forces to reach continuous tilt angles. The mirrors are fabricated using multi user MEMS processes.
We design microfluidic environments for targeted investigations of colloid transport. Focus of this work are particle-particle interactions, as well as particle-wall interactions. This study will lead to design recommendations for robust microfluidic devices.