Precise Steering of Particles in Electroosmotically Actuated Microfluidic Devices

Abstract

Title of dissertation: PRECISE STEERING OF PARTICLES IN ELECTROOSMOTICALLY ACTUATED MICROFLUIDIC DEVICES Satej V. Chaudhary, Doctor of Philosophy, 2010 Dissertation directed by: Professor Benjamin Shapiro Department of Aerospace Engineering In this thesis, we show how to combine microfluidics and feedback control to independently steer multiple particles with micrometer accuracy in two dimensions. The particles are steered by creating a fluid flow that carries all the particles from where they are to where they should be at each time step. Our control loop comprises sensing, computation, and actuation to steer particles along user-input trajectories. Particle positions are identified in real-time by an optical system and transferred to a control algorithm that then determines the electrode voltages necessary to create a flow field to carry all the particles to their next desired locations. The process repeats at the next time instant. Our method achieves inexpensive steering of particles by using conventional electroosmotic actuation in microfluidic channels. This type of particle steering has significant advantages over other particle steering methods, such as laser tweezers. (Laser tweezers cannot steer reflective particles, or particles where the index of refraction is lower than that of the surrounding medium. More sophisticated optical vortex holographic tweezers require that the index of refraction does not differ substantially from that of the surrounding medium.). In this thesis, we address three specific aspects of this technology. First, we develop the control algorithms for steering multiple particles independently and validate our control techniques using simulations with realistic sources of initial position errors and system uncertainties. Second, we develop optimal path planning methods to efficiently steer particles between given initial and final positions. Third, we design high performance microfluidic devices that are capable of simultaneously steering five particles in experiment. (Steering of up to three particles in experiment had been previously demonstrated [1].) PRECISE STEERING OF PARTICLES IN ELECTROOSMOTICALLY ACTUATED MICROFLUIDIC DEVICES by Satej V. Chaudhary Dissertation submitted to the Faculty of the Graduate School of the University of Maryland, College Park in partial fulfillment of the requirements for the degree of Doctor of Philosophy 2010 Advisory Committee: Dr. Benjamin Shapiro, Chair/Advisor Dr. Robert Sanner Dr. Christopher Cadou Dr. Alison Flatau Dr. Howard Elman, Dean’s Representative c © Copyright by Satej V. Chaudhary 2010

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@inproceedings{Chaudhary2010PreciseSO, title={Precise Steering of Particles in Electroosmotically Actuated Microfluidic Devices}, author={Satej Chaudhary and Benjamin Shapiro and Alison B. Flatau}, year={2010} }