Department: Electrical & Computer Engineering
Name: Randy Chen
Email: chc008 @ gmail.com
Grad Year: 2009
Sunghwan Cho, shc002 @ ucsd.edu | Jessica Godin, jgodin @ ucsd.edu | Frank Tsai, frank.sftsai @ gmail.com
Our research group develops enabling technologies for lab-on-a-chip flow cytometry devices. These small, disposable chips are intended to incorporate the full functionality of the benchtop cytometer on an inexpensive, mass-producible platform. Traditional flow cytometers are clinical and research instruments used for diagnostics, such as blood panels and HIV monitoring, and numerous biological assays. A flow cytometer detects scattered light and excited fluorescence and uses this information to identify each cell in a sample, allowing it to sort out cells of interest downstream. Our developments will make these devices more widely available and potentially portable, greatly aiding biomedical research and clinical diagnostics in industrialized nations, and hopefully extending the clinical services of this tool to developing nations as well.
We take a comprehensive, multi-disciplinary approach to system design and fabrication, involving microfabrication, microfluidics, acoustics, photonics, and electronics. Our current work includes the development of (1) two-dimensional polymer-based fluid-filled lenses, (2) on-chip miniaturized adaptive polymer microscopes, (3) microfluidic flow control and acoustics-based cell sorting. Our recently-developed in-plane lenses (1) have been incorporated into a detection-only cytometer device, affording us the ability to detect light scattering in the same fashion as a traditional cytometer (a capability most microfluidic cytometers are lacking). In addition, these lenses allow for more uniform sample illumination and more efficient light collection, yielding a stronger signal that has enabled our devices to operate with small, low-powered laser diodes and semiconductor detectors to make them smaller, lighter, and lower-cost. Miniaturized microscopes (2) can be achieved with bio-inspired adaptive optics. We have previously demonstrated low-cost adaptive optics that can perform focus point and field-of-view change. Now we are improving this technology and applying it to micro-fluidics. This technology promises low-cost microscopes for imaging and enhanced light collection. Manipulation of microfluidic flow control (3) can be achieved with the newly-designed micropump. Having developed a novel Cu-PDMS bonding technique, we have successfully fabricated PDMS-based micro-nozzle/diffuser. The new micropump allows precise fluid control (e.g. flowrate) and has shown great promise in high-throughput sorting of biological agents. Our final goal is to integrate all of these components into a high-sensitivity, high-throughput, low-cost flow cytometer chip.
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