CU MEMS Microfluidic Platform for Sorting and Manipulation of Single Magnetic Particles and Biomolecules

	Multidisciplinary Engineering Micro-Systems Group Mechanical Engineering: University of Colorado at Boulder
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Manipulation and Detection of Superparamagnetic Beads with Spin-Valves

PIs: Victor M. Bright, John Moreland (NIST)
Student: Wendy R. Altman

Project field/specialty: Microfluidics, Spin-valve sensing, Superparamagnetic bead detection, MEMS

Project Description:This research demonstrates the feasibility a new magnetic manipulation technique to trap, release, transport, and detect superparamagnetic beads (SPBs) with low-power and addressable spin-valves (SVs). Functionalized superparamagnetic beads are used as “mobile substrates” in numerous bioassays; examples of applicable bioassays include protein and DNA purification, cell fractionation, enzyme immobilization, and immunoassays. SV technology is based on the giant magnetoresistance (GMR) effect and is commonly used in high-density magnetic recording heads and magnetic field sensors. The SV consist of two magnetic layers separated by a spacer layer. An antiferromagnetic (AFM) layer pins the magnetization of one ferromagnetic (FM) layer in one direction while the other FM layer remains free to rotate. When the two layers are parallel (low resistance state), the high magnetic field gradient will attract and trap a SPB. When the two layers are antiparallel (high resistance state), the gradient is low and the SPB will no longer be attracted to the SV; the SPB will be released. In addition to SPB capture and release, the stray fields from a trapped and magnetized SPB affect the SV resistance response, thus a trapped SPB can be detected. The scope of this research includes the design, fabrication, and characterization of the microfluidic and micro-electromechanical system (MEMS) to manipulate and detect SPBs using nonvolatile and locally addressable SVs.

Funding Source: NIST

Publications/Conferences:

W.R. Altman, J. Moreland, S.E. Russek, B.W. Han, and V.M. Bright, "Microfluidic Transport and Sensing of Functionalized Superparamagnetic Beads using Integrated Spin-Valves," Abstract accepted for Micro-TAS, Seattle, October 2-6, 2011(Poster).
W.R. Altman, J. Moreland, S.E. Russek, B.W. Han, and V.M. Bright, "Microfluidic Transport of Superparamagnetic Beads with Spin-Valve Traps", Manuscript submitted, July 2011.
W.R. Altman, J. Moreland, S.E. Russek, and V.M. Bright, "Optimization of Spin-Valve Parameters for Magnetic Bead Trapping and Manipulation," Journal of Magnetism and Magnetic Materials, 2010.
W.R. Krauser*, J. Moreland, S.E. Russek, V.M. Bright, "Magnetic Switching Characteristics of Spin-Valves designed for Bead Trapping and Manipulation," 11th Joint MMM-Intermag Conference, Jan. 16-22, 2010 Washington, D.C., USA (Talk).
W.R. Krauser*, S.E. Russek, V.M. Bright, and J. Moreland, “Switching Characteristics of Magnetic Spin-Valve Traps for Magnetic Bead Manipulation in Microfluidics,” 7th Int. Conf. on the Scientific and Clinical Applications of Magnetic Carriers, May 21-24, 2008, Vancouver, Canada, (Poster).
J. Moreland, D. Porpora, W.R. Krauser*, and V.M. Bright, “Magnetic Templates for Nanometer Scale Manipulation and Assembly,” MMM2007: The 10th Magnetism & Magnetic Materials Conference, Jan. 7-11, 2007, Baltimore, MD (Invited Talk).