SEM PICTURES OF A SEQUENTIAL MICROFLUIDIC BUBBLE PUMP ON SILICON

Microfluidic Lab-on-a-chip. A microfluidic platform provides a base for high throughput drug screening, drug delivery and point of care diagnostics. My current research in microfluidics focused on development of novel actuation mechanisms and microfluidic components for fluid manipulation in microchannels. Our approach is based on the actuation characteristics of electrolytic bubbles that are formed directly inside the microfluidic channels. This provides a robust and easily fabricated set of microfluidic components including valves, pumps, switches, and logic on an integrated chip. The actuation is electrically driven, consumes miniscule power, and requires no moving mechanical parts. In conjunction with cell-based biosensors, this effort is being further expanded to making integrated microfluidic lab-on-a-chip. Research activities include design and microfabrication of fully integrated microfluidics systems, fluid dynamics studies of bio-fluids in microchannels, interface studies of gas, liquid and solid materials under varying fluid flow conditions, and biocompatibility of materials.

        Solution chemistry and pH effect for saline as fluid.

Illustration of a working bubble valve.

      Cell based biosensors. The regulation of cell volume was one of the earliest evolutionary demands for life, and is a key measure of cell health. The current research in biosensors is focused on developing cell based sensing and diagnostic systems that utilizes the cell volume change to monitor how cells respond to drugs or detects toxic chemicals. During the course of sensor development we investigate biocompatibility of sensor materials, electronics for transduction of the biological signal, microfluidic characteristics of the testing reagents, and nanofabrication processes & design. Since the cell’s interior osmotic pressure (solute composition) reflects the state of metabolism and the balance of its membrane permeability, these sensors are being used to study various cellular activities and cell response to different chemicals, pharmaceutical agents, and environmental toxicity.

Impedance based cell volume sensor.  The adherent cells on a solid substrate are placed in a shallow chamber. Changes in cell volume displace the extracellular fluid in the chamber, thereby changing the resistance across the chamber. Thus, cell swelling is observed as an increase in resistance.

Nanoconductors for single molecule detection. This research is focused on processing of nanoscale conductors by electrochemistry and ultra high vacuum route, their characterization, and fundamental understanding of their electronic properties. Specifically, I am interested in using ballistic conductors for single molecule detection and their characterization at the quantum level. These ballistic conductors are being made through a series of nanofabrication and controlled electrodeposition steps that we have developed. We work on the materials structure studies, chemical reactions for targets molecules, and electron transport behavior under specific chemical environments.