Integrated Microfluidic Systems for Continuous Particle Sorting
Particle sorting, counting, and separation are crucial precursor steps to a host of biomedical assays, and various macroscale tools have been developed over the past several decades in response. In more recent years, microfluidic technologies have gained significant popularity as a means of performing these same tasks and more, all at reduced power, reagent volume, time, and user difficulty. This raises the possibility that every fluidic, optical, and electronic system in a biomedical laboratory could soon be reduced to a microscale equivalent, and incorporated onto a single handheld device, a hypothetical lab-on-a-chip. However, while the sorting technologies at the heart of this new class of device have developed at a dramatic pace, the devices themselves remain costly to fabricate, difficult to manufacture at large scales, and poorly integrated with auxiliary systems such as power supplies and peristaltic pumps. As such, they rarely develop beyond the proof-of-concept stage and have yet to achieve any significant acceptance in the biomedical community. This work seeks to move microfluidic sorters beyond this obstacle. First, it was demonstrated that multiple components could be implemented onto a single platform, eliminating cumbersome external fluidics in the process. Next, methods from the mature microelectronics industry were used to build an electronic microfluidic cell sorter on a printed circuit board platform, yielding a dramatic improvement in device manufacturability and user friendliness, as well as ease of integration with other electronics, micro or otherwise. Finally, building on this, a method was developed to manufacture large numbers of three-dimensional microelectrodes and then incorporate them into a microfluidic device using pick-and-place methods, again a technique adapted from the microelectronics industry. Together, this shifts microfluidics away from the established standard of cumbersome devices monolithically constructed using costly materials and methods and towards a novel standard of more manufacturable and user-friendly devices, and represents a step towards this class of device gaining mainstream acceptance in the biomedical community.