Bio-MEMS and Microfluidics Laboratory
Dr. Susan Hua

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RESEARCH PROJECTS

Microfluidic Lab-on-a-chip
To successfully implement on-chip cell-based sensing and diagnostics, it is essential to have a high throughput sample handling and preparation system, i.e., a microfluidic Lab-on-a-Chip. In the past years, we have successfully developed a microfluidic system that utilizes electrolytic bubbles as sensors and actuators for flow measurements and control on chip. Advantages of this approach include high actuation speed, absence of any moving mechanical parts, and simple microfabrication capable of large-scale integration. We are now focused to integrate both fluid actuators and sensors on a single platform to develop a complete Lab-on-a-Chip. In conjunction with cell-based biosensors, this effort is being expanded to make high throughput Lab Chip for drug screening. Research activities include design and microfabrication of fully integrated microfluidics systems, fluid dynamics studies of bio-fluids in micro-channels, interface studies of liquid and solid materials under varying fluid flow conditions, and biocompatibility of materials.

Cellular transport studies using microfluidic sensors
The transport of ions and organic solutes across a cell membrane reflects cellular metabolism, neurotransmitter activity, as well as interaction with extracellular environment. Since transport can change intracellular and extracellular osmolarity, it leads to changes in cell volume. We have developed an impedance-based microfluidic volume sensor that is capable of measuring cell volume changes in real time in single cells as well as in cell population. We are now using volume sensor to study cell response to extracellular stimuli including shear stress, cell-matrix interaction, pharmaceutical agents, and environmental toxicity. One of our main interests is to gain the understanding of sensory mechanisms for cell volume regulation and transport mechanisms in renal epithelial cells.

Development of sensors for probing cellular communication
Cells in tissues and organs coordinate their activities by communicating with each other, and this communication is mediated by specialized channels, called gap junctions. Through the gap junction channels, cells synchronize their electrical and metabolic activities, transmit intercellular signals, resulting in regulation of cell growth and differentiation, and maintenance of metabolic homeostasis. This project aims to develop novel microfluidic sensors that are capable of probing intercellular communications via gap junction channels. The research involves design and control of the multi-stream flow in a microfluidic channel, on-chip cell culture in the functionalized regions of the sensor, detection of intercellular communication pathways using fluorescence and impedance measurements and their response to extracellular stimuli.

High-speed Microfluidic Thermal Stimulator
Temperature has strong effects on cell function and cellular processes. In addition to the general thermal effects on ion channel kinetics, the discovery of heat-gated ion channels in neurons has focused interest on thermosensing pathways. Microfabricated devices offer the advantage of precise control over thermal input and fast temperature changes over a very small volume of the test solution. Our research involves the development of microfluidic thermal devices that produce rapid temperature jump and accurate temperature control, demonstration of their applications in physiology. Specifically, we use the microfluidic thermal device to produce “step” changes in temperature and study the kinetics of heat stimulated currents using patch clamp.

RESEARCH FUNDING