Automated design of digital microfluidic lab-on-chip under pin-count constraints

Digital microfluidic biochips, as referred to as lab-on-a-chip, are revolutionizing DNA sequencing, immunoassays, and clinical diagnostics. Bioassays steps are mapped to a sequence of microfludic operations on a two dimensional array of electrodes. The number of independent input pins used to control the electrodes is an important cost-driver, especially for disposable PCB devices that are being developed for clinical and point-of care diagnostics. We review two design-automation methods for such pin-count-constrained biochips. The first design procedure relies on a droplet-trace-based array partitioning scheme and an efficient pin assignment technique, referred to as the "Connect-5 algorithm". The second pin-constrained design method relies on cross-referencing addressing based on "rows" and "columns" to access electrodes. An efficient droplet manipulationmethod is presented for this cross-referencing technique based on a mapping of the droplet-movement problem to the clique-partitioning problem from graph theory