Abstract

Extreme Microfluidics: Large-Volumes and Complex Fluids

Mehmet Toner, Helen Andrus Benedict Professor of Biomedical Engineering; Director, BioMEMS Center, Mass General Hospital and Harvard Medical School

Microfluidics gained prominence with the application of microelectromechanical systems (MEMS) to biology in an attempt to benefit from the miniaturization of devices for handling of minute samples of fluids under precisely controlled conditions. Microfluidics exploits the differences between micro- and macro-scale flows, for example, the absence of turbulence, electro-osmotic flow, surface and interfacial effects, capillary forces in order to develop scaled-down biochemical analytical processes. The field also takes advantage of MEMS and silicon micromachining by integrating micro-sensors, micro-valves, and micro-pumps as well as physical, electrical, and optical detection schemes into microfluidics to develop the so-called “micro-total analysis systems” or “lab-on-a-chip” devices. However, the ability to process ‘real world-sized’ volumes efficiently has been a major challenge since the beginning of the field of microfluidics. This begs the question whether it is possible to take advantage of microfluidic precision without the limitation on throughput required for large-volume processing? The challenge is further compounded by the fact that physiological fluids are non-Newtonian, heterogeneous, and contain viscoelastic living cells that continuously responds to the smallest changes in their microenvironment. Our efforts towards moving the field of microfluidics to process large volumes of fluids was counterintuitive and not anticipated by the conventional wisdom at the inception of the field. We metaphorically called this “hooking garden hose to microfluidic chips.”  We are motivated by a broad range of applications enabled by precise manipulation of extremely large volumes of complex fluids, especially those containing living cells or bioparticles. The use of high-throughput microfluidics to process large-volumes of complex fluids (e.g., whole blood, bone marrow, bronchoalveolar fluid) has found broad interest in both academia and industry due to its broad range of utility in medical applications.