Microfluidic Separations

Microfluidic-based separations benefit

from the ability to control fluids with high precision and the reduction of cost, total analyisis times, and sample and reagent consumption. Electrokinetically driven separations on microfluidic devices have generated efficiencies per unit length similar to or exceeding that of conventional capillary systems. We are currently developing microfluidic devices with various geometries optimized for one- and two-dimensional separations that will shorten analysis times and improve the peak capacity, accuracy, and reproducibly compared to conventional techniques. We are also using this technology to study the onset and progression of diseases such as cancer.

Nanofluidics

In addition to developing sophisticated microscale

analysis systems, of particular interest is how device function scales when one or more of the conduit dimensions is on a nanometer length scale, and what advantages, if any, there might be for separations. nanofluidic systems can be significantly influenced by phenomena such as double layer overlap, surface charge, diffusion, and entropic forces, which are either insignificant or absent in larger microchannels. To develop analytical functions from these unique nanofluidic phenomena, we are studying fundamental fluid and material trasport and applying what is learned to separation and sensing problems, e.g., creating turnable particle/molecular filters and monitoring supramolecular assembly. Presently, we are developing electronic equivalent of nanofluidic devices and planar multi-pore devices which will be used towards sensing of particles such as viruses.

Cell-Based Assays

The ability to study a single bacterium

or small ensembles of bacteria is integral to answering some of biology’s most complex problems. Microfluidic platforms are a unique and useful tool to create micro- and nanoscale features feasible of containing micron-sized bacteria, to handle extremely small fluid volumes (attoliters!), and to systematically study the behavioral response of bacteria to a host of environmental changes such as media, flow rate, and viscosity. To this end, in collaboration with Prof. Yves Brun of the Indiana University Department of Biology, we have developed microfluidic systems to study the bacterium Caulobacter crescentus. Fundamental studies are currently underway to monitor the swimming behavior of these bacteria in confined spaces and determine how motility affects cellular processes. Additionally, the adhesive holdfast that tethers C. crescentus to a host of surfaces has been identified as nature’s strongest glue; this adhesive shows great promise in a variety of biomedical applications, so projects in this area of the Jacobson group also involve probing the adhesive properties of this bacterium and determining factors that affect adhesion.