Authors: D. Irimia and M. Toner
Affilation: Massachusetts General Hospital, Harvard Medical School, United States
Pages: 659 - 661
Keywords: valve, cell suspension, large particles
Lab-on-a-chip devices for cell processing and analysis are increasingly sophisticated and targeting a wider spectrum of scientific research and clinical diagnostic applications. Despite recent advances however, many sample preparation steps, common for macro-scale techniques, have not yet been implemented in microfluidic systems. One example is centrifugation, which is commonly employed for increasing the concentration the chip. Here we present a new microfluidic design, physically implemented using standard soft lithographic techniques, which enables the handling of suspensions of eukaryotic cells and three orders of magnitude increase of the cell concentration. In a significant departure from existent elastomeric microscale valves, our approach allows the integration of multiple structures on the same membrane, and the execution of complex sequential procedures using a limited number of control steps. In our design, a mobile sieving barrier in closed position could trap cells mechanically, and could be subsequently opened to allow the trapped cells to pass into an outlet channel. At the same time, the suspension fluid passing through the 3 x 10 µm openings in the sieve, was directed not into the outlet channel but instead was guided into a drain channel and removed from the cell suspension, by a second barrier.