SÉMINAIRE OUVERT !
14h00 à 15h00
Amphithéâtre Pierre Gilles De Gennes
(bâtiment Blaise Pascal, INSA de Lyon, campus LyonTech-la Doua, Villeurbanne)
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par Christopher S. LYNCH,
Dean Bourns College of Engineering UC Riverside
Magnetoelectric cell sorting offers the potential to sort large numbers of cells quickly. Cells can be tagged with fluorescent markers that identify cell type. They can also be tagged with magnetic micron or smaller magnetic beads. These beads experience a translational force in the presence of a magnetic field gradient. Macro scale cell sorting magnetically tags cells that are to be captured, making it possible to hold those cells and remove the unwanted cells. Magnetoelectric devices offer the ability to control magnetism at the sub-micron scale.
There are multiple challenges faced when applying magnetoelectric devices to cell sorting. In an envisioned device, the magnetically tagged cell is in a fluid bath that flows across a nanomagnet. The magnet traps the cell. Ideally, when voltage is applied, the cell is released. Some of the challenges include: the design of nanomagnets to produce the right force to trap and hold a cell in a flow field, and the ability to alter the magnetization in a way that enables releasing the cell. Ideally, an applied voltage would turn the magnetization off completely. The approach taken to developing a voltage-controlled magnet was to produce magnetostrictive structures on a piezoelectric substrate. At small length scales this approach can be used to produce single domain magnets with the magnetization in-plane. In certain systems like a NiCo layered structure, when the layers are thin enough, interface effects dominate and the magnetization shifts to an out-of-plane orientation. The work that will be presented describes the design of the nanomagnets to produce the desired capture force, the fabrication and characterization of an array of nanomagnets under an applied magnetic field to produce M-H curves, and the effect of strain on those M-H curves. Although the ability to switch these magnetic structures from a state of perpendicular magnetic anisotropy to an in-plane magnetic state has not yet been demonstrated, sufficient progress has been made to suggest that the approach may ultimately be successful.
Prof. Lynch performed his MS, PhD, and Post Doctoral work at UC Santa Barbara. He joined the Woodruff School of Mechanical Engineering at Georgia Tech in 1995 and the Department of Mechanical and Aerospace Engineering at UCLA in 2007 where he served as director of the #2 ranked MS Online program and as the Mechanical and Aerps[ace Engineering department chair. On September 1, 2018 he moved to UC Riverside to serve as Dean of the Bourns College of Engineering.
His research focuses on characterization, applications, and modeling of ferroelectric and magnetostrictive materials. He has contributed to the development of constitutive models based on internal state variables, on micromechanics, and on the phase field modeling; and to improved material reliability through his contributions to experimental and analytical field coupled constitutive measurements and fracture mechanics. His experimental data and related modeling work have been implemented in codes that his research group uses in the design and development of ferroelectric-based devices. This includes recent work on magnetoelectric coupling at the nanoscale. He leads the modeling thrust of the NSF TANMS NERC. He has published over 180 journal articles and conference papers. Details can be found on his Google Scholar profile.
Prof. Lynch has served as chair of the ASME aerospace division. He founded a conference on smart materials and adaptive structures, ASME SMASIS, and served as the general chair of the annual SPIE Smart Structures conference for 2014-2015. He has been honored with receipt of the NSF CAREER award, the ONR Young Investigator award, an ASEE educator award, as Fellow of ASME, Fellow of SPIE, the ASME Smart Structures Prize, the SPIE Smart Materials and Structures Lifetime Achievement Award, several teaching awards, serves as an associate editor of a new journal Multifunctional Materials, and is the editor-in-chief of the journal Smart Materials and Structures.
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