Automated Fabrication of Bio-Polymer Structures by Optically-Induced Dielectrophoresis

We propose to develop a simple, inexpensive, flexible, and automated method for fabricating three-dimensional (3D) cross-linked networks of photoactive bio-polymers (e.g., poly(ethylene glycol) (PEG)-diacrylate hydrogel or PEGDA) using theoptically-induced dielectrophoretic(ODEP) force. Instead of using traditional micro-photolithographic techniques, in which an ultra-violet (UV) light source and relatively expensive masks are required for patterning bio-polymers, we have demonstrated recently that static and dynamic non-UV optical patterns can be used as virtual electrodes to generate the ODEP force, which induces localized 3D solid hydrogel formation, producing hydrogel structures with thickness dimensions down to the nanometer scale and lateral dimensions on the order of a few microns. The thickness of these structures can be well-controlled via the exposure time to the ODEP force. The ultimate goal of this project is to demonstrate anautomatedandsynchronizedODEP Platform, which links with a microfluidic system with an embedded ODEP chip, to rapidly fabricate 3D free-standing polymer structures. In order to achieve the ultimate goal of this project, we must explore several fundamental issues related to this novel fabrication technique: 1) understand and accurately model the electrokinetics phenomena, including AC electro-osmosis and light-induced electrothermal forces, during the polymer formation process under the ODEP force field; 2) elucidate the time-dependent formation process of ODEP-fabricated polymer structures, i.e., determine how the ODEP force field evolves near the ODEP chip surface and affects the resulting structural shape of the polymer over time; 3) investigate the dynamic polymer formation process under a constant ODEP force field, i.e., we have observed that, under specific polymer solution concentrations, it is possible to project a single static image to continuously generate micron-sized structures; 4) study and optimize the ODEP parameters for the polymerization process, in order to better design a microfluidic system, as an ‘automated polymer factory”, to continuously generate micro polymer particles and structures. The project team will performed detailed experimental work and numerical simulations to understand and solve these fundamental problems through the funding of this project. The key deliverables of this project are: a) a custombuilt ODEP Platform to enable theautomatedgeneration of micro bio-polymer structures with resolution of ~1µm; b) a microfluidic system that synchronizes with the ODEP Platform and facilitates the continuous generation of micron-sized bio-polymer structures in its microchannels; c) a software algorithm to automatically detect the formation of polymer structures in the microfluidic system, and to synchronize with switching flow valves to transport the fabricated free-standing polymer structures to designated reservoirs; d) an in-depth understanding of the ODEP-based polymerization process through cross-validation of experimental and simulation data obtained from the project. We believe that the new technologies developed from this project will provide an entirely new paradigm for micro polymer fabrication, which could find potential applications in the advanced fields of tissue engineering, drug delivery, and spectroscopic encoding.