(411h) Computational Design and Experimental Verification of Microfluidic Platforms for Deterministic Arraying of Microparticles for Point-of-Care Applications

Bead based microarrays are promising platforms for implementing the high throughput, multiplexed assaying of the binding interactions of biomolecules (for example the binding of antigens and antibodies, or the conjugation of membrane receptors with small molecule ligands). In these arrays, each bead contains a particular probe molecule on its surface, and a code to identify this probe. Particles with different probes are mixed and subsequently bound onto a surface in a regular array. The array is then incubated with a target, and the binding of the target to particular probe molecules is identified (usually by fluorescently labeling the targets and scanning to find luminescent beads). The bead code is then read to identify the probe and complete the multiplexed assay. The promise of this platform lies in the fact that by decreasing the size of the beads, ultra-mininaturized platforms capable of an increased number of binding assays can be constructed.

Bead arraying is essential to the formation of these bead based microarrays, and most research has focused on using the covalent binding of functional groups on the bead surface to functionalized sites on the platform surface. Arraying paradigms which sequester particles without reaction have the distinct advantage that they avoid chemical reaction conjugation. This presentation describes the design of a microfluidics cell for the placement, through flow, of micron-sized objects in a two dimensional array on a planar surface. In this presentation, a microfluidic obstacle course is proposed in which funnel-shaped capture elements are arranged inside a planar microfluidic cell to deterministically capture microparticles in prescribed locations. Exhaustive computational fluid dynamics simulation of streamline patterns are used a s a guide to optimize parameters such as the shape of the capture elements and their separation distances in order to achieve the highest possible capture percentage arranged in aligned configurations. Based on the optimized parameters, PDMS based devices are fabricated and tested with suspensions of neutrally buoyant polystyrene particles in DI water which shows the capability of this method to deterministically array particles in prescribed locations.

The ability to accurately array microbeads using flow fields will overcome one of the difficulties in integrating bead-based arrays with microfluidic devices. As the result of this research, point-of-care systems for identifying common infectious diseases could be in every doctor's office in the near future. It could also bring low cost integrated sensors, such as pathogen detection sensors, into environmental monitoring systems.