Design for Restricted-Area and Fast Dilution using Programmable Microfluidic Device based Lab-on-a-Chip

Microfluidic lab-on-a-chip has emerged as a new technology for implementing biochemical protocols on small-sized portable devices targeting low-cost medical diagnostics. Among various efforts of fabrication of such chips, programmable microfluidic device (PMD) is a relatively new technology for implementation of flow-based lab-on-a-chips. A PMD chip is suitable for automation due to its symmetric nature. In order to implement a bioprotocol on such a reconfigurable device, it is crucial to automate sample preparation on a chip as well. Sample preparation, which is a front-end process to produce the desired target concentrations of the input reagent fluid, plays a pivotal role in every bioassay or bioprotocol. In this paper, first, a method referred as dilution algorithm in two steps (DATS) is proposed, which needs only two diluting operations for any target concentration to achieve. Then, we present another method called as dilution algorithm on a small dilution area (DASDA), which needs less area compared to that by DATS. Finally, we propose the heuristic for efficient dilution of biochemical fluids using a PMD chip referred as dilution algorithm in a restricted dilution area (DARDA) that produces more accurate (with less error) target concentration value on a restricted area of the PMD chip in a shorter mixing time. Simulation results reveal that DARDA outperforms a start-of-the-art dilution algorithm applicable for PMD chips in terms of three performance parameters namely mixing time, mixing area and error in target concentration.