Micro-Particle Operations Using Asymmetric Traps

[摘要] Micro-particles are a great tool to detect biomolecules for their high multiplexing capability, wide options of materials, and scalability. Currently, most of the platforms utilizing micro-particles are bench-top scale instruments equipped with bulky devices for fine spatiotemporal control of micro-particles. This requirement for resources restricts the environment where micro-particles can be applied. To this problem, microfluidic techniques are an attractive solution because of its inherent capability of fine controlling of micro-particle due to scale matching.This dissertation describes the development of the micro-particle operations using the asymmetric trap, a new mechanical trap that has flow direction dependent particle capturing behavior. Based on the theory of deterministic lateral displacement of micro-particle in periodic obstacle array and mass balance relationships, we provide a model that connects characteristic trap-particle interactions to critical dimensions including particle diameter and the gaps of the asymmetric traps. We theoretically predicted and experimentally observed five different trap-particle interactions including one-way particle transport, symmetric passage, symmetric capturing, trap skipping in zig-zag mode, and trap skipping in bump mode. Our model could explain most of the experimental results (particle diameter = 20.3 µm, Re < 0.01).Based on our modeling of particle dynamics in the asymmetric traps, we explore micro-particle operations using the asymmetric traps. One-way particle transport, the basic transport function using asymmetric traps, could displace hundreds of micro-particles across trap rows in only a few fluid oscillations (<500 ms per oscillation). On top of that, the segregation, medium exchange, and focusing and splitting of micro-particle in oscillatory flow were accomplished by capitalizing on two features: difference in the transport speeds of the trap-particle interaction dynamics and transport polarity of the asymmetric traps. At first, segregation of micro-particle mixture was achieved by utilizing the difference in transport speeds of trap-particle interaction dynamics. In the investigation of factors of the segregation performance, we found that the number of rows is the critical factor for a high performance of the segregation. Next, medium exchange of the particles in oscillatory flow was successfully demonstrated. At modest amplitude and number of fluid oscillations, the particle could be displaced into a new medium over the mixing region. Lastly, we could focus and split of groups of micro-particles in a few fluid oscillations by exploiting transport polarity of the asymmetric traps.

[发布机构] University of Michigan

[效力级别] Microparticle

[关键词] Microfluidics;Microparticle;Particle Operations;Separation;Oscillatory Flow;Chemical Engineering;Engineering (General);Physics;Engineering;Science;Chemical Engineering