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Title:Development and application of the stokes trap for measurement of interparticle interactions
Author(s):Shenoy, Anish
Director of Research:Schroeder, Charles M.
Doctoral Committee Chair(s):Hilgenfeldt, Sascha
Doctoral Committee Member(s):Rao, Christopher V.; Chen, Qian
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Directed assembly
Stokes flow
Particle manipulation
Particle trapping
Abstract:The ability to trap and control single particles in free solution has led to major advances in science and engineering. Common methods for particle trapping and manipulation often rely on optical, magnetic, acoustic, or electric forces. However, the vast majority of these methods critically depend on the target particle possessing specific physical properties such as index of refraction or surface charge. In this research, we have designed and built a Stokes trap, which allows for the manipulation and control of an arbitrary number of arbitrary type particles using only fluid flow. In this way, we have effectively constructed a `smart microfluidic device' by coupling feedback control with microfluidics, thereby enabling new routes for the fluidic-directed assembly of particles. This work is comprised of three distinct but interrelated efforts towards the precision trapping and manipulation of multiple particles using fluid flow. In the first project, the control algorithm for a microfluidic process is extensively studied for confining a single particle in solution. Here, we study the response of trapped particles actuated using a combination of proportional, integral, and derivative controllers (PID control), which extends beyond our prior work where we utilized a simple proportional controller for 2-D manipulation of particles in free solution. We investigate the effect of controller gains, flow rate, and feedback response times on the robustness of trapping, using a combination of simulation and experimental studies. In the second project, we present the development and application of the Stokes Trap, which is a multiplexed microfluidic method for arbitrary manipulation of an arbitrary number of particles in solution. We demonstrate simultaneous manipulation of two particles in a simple microfluidic device, and also achieve fluidic directed assembly of multiple particles in solution. In the third project, the Stokes trap is used to implement and experimentally demonstrate trajectory control using fluidic trapping, wherein particles are controlled by a path-following framework that improves the precision and the speed of manipulation of particles along arbitrary paths. An extended Kalman filter is also implemented, which effectively reduces the offset due to unmodeled phenomena during particle trapping. Finally, these techniques are leveraged to demonstrate the direct determination of solvent-mediated hydrodynamic interactions (HI) between two freely suspended colloidal particles in flow. From a broad perspective, this work provides a robust framework for studying fundamental interactions between particles or for guiding the directed assembly of materials.
Issue Date:2017-06-16
Rights Information:Copyright 2017 by Anish Shenoy
Date Available in IDEALS:2017-09-29
Date Deposited:2017-08

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