The integrated microfluidic systems laboratory is an experimental research lab that focuses on microfluidic flow visualization (including micro particle image velocimetry) and microfabrication of such platforms. We also investigate electrokinetic methods in microfluidic systems for particle and cell manipulation and analysis. Below is a list of ongoing research projects in our laboratory
Our group has expertise in microscale electrokinetic mechanisms including dielectrophoresis (DEP) and electrohydrodynamics (ACEO, ET flow, etc.). These techniques offer sample manipulation schemes without moving parts and, in most cased, straightforward microfabrication techniques. Most of these mechanisms can be driven with a standard benchtop waveform generator with electric fields on the order of 106 V/m.
We are investigating the use of a unique electrode configuration that yields a constant dielectrophoretic force. This curvature produces a constant gradient field-squared; traditional DEP systems (ex: interdigitated electrodes) can have considerable differences in the DEP force field, especially near electrode edges. The isoDEP platform enables particle tracking velocimetry to be used to extract the dielectric properties of individual particles. By extracting the dielectric signature of individual particles subpopulation species can be identified and analyzed.
In 2016 we had an experiment conducted on the International Space Station that investigated the long-term stability of a colloidal solution in the presence of nanoparticles. Sample stability (i.e. prevention of particle aggregates) is a function colloid zeta potential, nanoparticle charge, and nanoparticle concentration. We will investigate the effects of an electric field on the stability and assembly of a nanoparticle-laden solution on the ISS in 2019.
Impedance spectroscopy (aka EIS) is a non-invasive, real-time technique than can measure the dielectric characteristics of a sample. We have applied this technique in a microfluidic chip to monitor the integrity of an endothelial monolayer in vitro . We can monitor the response of the endothelium when subjected to external mechanical and chemical stimuli.
Rapid Electrokinetic Patterning (REP)
REP is a technique that can manipulate colloids on an electrode surface dynamically through the use of reconfigurable illumination patterns. Our research team and collaborators have been able to translate, trap, sort, and manipulate microparticles (magnetic, metallic, and insulative), nanoparticles, bacteria, and carbon nanotubes. REP can be executed optically with a laser or broad light source (patterned using a traditional overhead projector) or without illumination through the use of integrated resistive heaters.
The electric curtain has been studied for decades; it is a platform where airborne particulates are repelled from a dielectric-coated electrode surface. We are studying the electric curtain when the particles have negligible charge and when energized air (plasma/ozone) is not present. Under these conditions dielectric phenomena and charge transfer dominate particle manipulation. Through careful understanding and balance of these mechanisms particle sorting (by size and by type) may be possible.
Our laboratory is investigating various methods of depositing colloids onto the surface of surfaces with various physical properties. Recently we are intersted in the effects of Kentucky bourbon on the formation of these porous-like colloid layers that are formed after liquid evaporation.
We acknowledge the support of Ultra Motion (www.ultramotion.com) for the use of precise linear actuators that aid in this investigation.