We develop new fundamental understanding in microfluidics and electrokinetics to create micro-scale diagnostic sensors and fluidic tools.
Research Topics
Electrokinetics involves the interaction between applied fields, ions, and particles to drive fluid flows and particle motion. Recent interests in nanotechnology and microfluidics have motivated developing the ability to harness this field-driven phenomena for precise fluid and particle manipulations across a broad range of biomedical and lab-on-a-chip (LOC) applications.
Detecting Biomolecular Binding at Liquid Interfaces
Our current research is focused on understanding how to detect biomarkers for disease based on changes using a process we recently defined as “interfacial electrokinetic transduction”, or IET. In IET, we use the motion of a liquid interface as the basis to create a biomolecular sensing transduction event.
Microfluidics for Sample Processing and Preparation
Another major research thrust in my lab focuses on leveraging direct current (DC) electrokinetic principles to develop tools for LOC sample processing for NASA. Long missions in deep space present a new set of challenges for maintaining the health, safety and performance of crews. In particular, the ability to screen for disease, establish deviations from health, and detect viral or bacterial infections both in humans and in cabin air or water systems are essential requirements for assuring the health of crew members during flight missions. The objective of this proposal is to develop a liquid handling and sample acquisition technology that is capable of simultaneous extraction of both proteins and nucleic acids from human body fluids and cabin water. Our current work focuses on developing these tools using microscale free flow electrophoresis (FFE) and isotachophoreis (ITP) tools for on-chip sample preparation.
Our microfluidic devices are equipped with a main flow channel and two separate electrode-containing channels. These electrode channels are fabricated directly against micropatterned regions of conductive carbon black (CB) nanocomposite membranes using our novel multistage soft lithographic process. The membrane serves to controllably reduce the current within the microchannels such that a DC electric field can exist to initiate electrophoretic processing, but does not produce any unwanted heating or Faradiac reactions.
Here is an example of what these devices look like:
Cell Migration and Microfluidics
My group also uses microfluidics as a tool to study cell behavior. For example, we recently explored the use of microfluidics to gain insight into the role that confined environments play in promoting the formation of cellular protrusions, including blebs and pseudopods, during chemotaxis.
We are also utilizing microfluidics platform to investigate the dynamics of cell migration under the influence of exogenous electric fields (e.g. Electrotaxis). Our group has the ability to study the migration of single cells in response to a variety of external cues using microfluidics.
Cellular Dielectrophoresis
We are also investigating how to use the electrokinetic method, dielectrophoresis (DEP) to electrically detect the presence of red blood cells (RBCs) that have been stored in refrigerated buffer and then reinfused into human circulation. Below, a quadrupole electrode array is used to separate cells that have been stored in a blood bank and reinfused into circulation (center of the array) from fresh cells (edges of the array.
