Salil P. Desai

Plastic masters—rigid templates for soft lithography

We demonstrate a simple process for the fabrication of rigid plastic master molds for soft lithography directly from (poly)dimethysiloxane devices. Plastics masters (PMs) provide a cost-effective alternative to silicon-based masters and can be easily replicated without the need for cleanroom facilities. We have successfully demonstrated the use of plastics micromolding to generate both single and dual-layer plastic structures, and have characterized the fidelity of the molding process. Using the PM fabrication technique, world-to-chip connections can be integrated directly into the master enabling devices with robust, well-aligned fluidic ports directly after molding. PMs provide an easy technique for the fabrication of microfluidic devices and a simple route for the scaling-up of fabrication of robust masters for soft lithography.

Electroactive hydrodynamic weirs for microparticle manipulation and patterning

We present a platform for parallelized manipulations of individual polarizable micron-scale particles (i.e., microparticles) that combines negative dielectrophoretic forcing with the passive capture of hydrodynamic weir-based trapping. Our work enables manipulations using ejection- andor exclusion-based methods. In ejection operations, we unload targeted weirs by displacing microparticles from their capture faces via electrode activation. In exclusion-based operations, we prevent weir loading by activating selected on-chip electrodes before introducing microparticles into the system. Our work describes the devices passive loading dynamics and demonstrates enhanced functionalities by forming a variety of particle patterns.

Analog tunable diffractive grating with milliradian resolution

We have designed and fabricated two versions of analog tunable grating. The extrapolated performance of the device is a wide tunable range between sub-nanometer and sub-micrometer with actuation voltage below 100 Volts by electrostatic actuation or 5 Volts by the piezoelectric version. We have demonstrated the preliminary function of our designs.