Design of Magnetic Field Concentrators By: Mohammed Zuned Desai Koji Hirota Michael Wong Areio Hashemi

Background Magnetic tweezers is a research tool for studying molecular and cellular mechanics Commonly used to study force regulated processes in biological systems Good resolution through a CCD (charged couple device) camera Exert no thermal or physical damage Functionality: Ability to measure forces on a particle using a magnetic field gradient. Simplicity: Simple models consist of a pair of magnets that are placed on top of the sample holder on an inverted microscope

Over all Purpose Design a magnetic tweezers device that is capable of obtaining force measurements up to at least 100 pN The tweezers should be designed in a way in that the sample will be able to be imaged using a bright-field transmission microscopy.

Clients Universities, Research Institutes, Biotech Companies, Laboratories Reason Device itself must be calibrated before its used, which implies the person must have some knowledge of the field If the customer were to buy all of the components it would be far too expensive for their budget i.e. cameras and microscope

Objectives Using FEMM (Finite Element Methods Magnetics) to predict the geometry and alignment of the magnets that will produce the largest possible magnetic field gradient. Machine and assemble the designs of four or six magnets that produce the largest field gradients using the FEMM results Calibrate the electromagnet assemblies, using procedures previously developed

Methods Determine the Best Core Size Determine the Best Coil Size Determine the Best Shape the Magnet Tip Determine the Best Alignment of two Magnets Determining the Best Design of the Apparatus Fabrication of the Apparatus Calibration of the Apparatus Using FEMMGeneral DesignProper Placement of Mirrors/Objectives Order Necessary Parts Designing and Attaching the Magnet Tip Setup Microscope and Bright-Field Transmission Design and Setup of the Magnets Setup of Camera and Computer Finding Linear Region of the Magnetic Fields Focusing Camera for Viewing Bead Movement Calculating Velocity of Beads from Measured Distance and Time and use Stokes Equation to fine the Force Exerted on the Beads

Setup Design Ibrahim UCR Bien June 2009

Design Innovations 1) Angle2) Arc 3) Cocave Angle 4) Flat Objective: Obtain design that will produce the largest magnetic field gradient

Sample Results Objective: Generate fine magnetic field lines

Sample Results Objective: Look for shape that provides the largest change in magnetic field

Magnet Design 1)Potential Problem 2)Experimentations

Budget ComponentPrice (US)In Stock Electromagnetic Magnets$20-$50 eachYes Magnet Power Supply$200Yes Aluminum plate$50-$200No Steel Rods (0.5inch diameter) $50-$100 eachNo CCD Camera$1,000-$10,000Yes Microscope$30,000-$40,000Yes Super paramagnetic beads$100-$500Yes

Potential Problems Machining the conical tip Fabrications of tip Too small, might crack How glue will affect results Working with a feasible distance Angular positioning of magnets Magnet coil turns Shipping time of magnets Calibrations Budget

Conclusion Design magnetic tweezers that can exert as much force as possible, preferable at least 100pN Using FEMM to determine the best theoretical model d Fabricate based on that model Calibrate to maximize the force output from the instrument Remarks: What makes our project unique from the other designs that are currently used is that we will be designing it in such a way that it will be compatible for the sample to be imaged using bright field transmission microscopy Being able to apply large forces

Can We Do It? We believe that we can achieve anything that we set our minds to achieve. - Anonymous

Questions?

References Neuman, Keri C, and Nagy, Attila. “Single-molecule force spectroscopy: optical tweezers, magnetic tweezers and atomic force microscopy.” Nature Publishing Group Vol. 5, NO. 6. June Danilowicz, Claudia, Greefield, Derek and Prentiss, Mara. “Dissociation of Ligand-Receptor Complexes Using Magnetic Tweezers.” Analytical Chemistry Vol. 77, No May Humphries; David E., Hong; Seok-Cheol, Cozzarelli; Linda A., Pollard; Martin J., Cozzarelli; Nicholas R. “Hybrid magnet devices fro molecule manipulation and small scale high gradient-field applications”. United States Patent and Trademark Office, An Agency of The United States Department of Commerce.. January 6, Ibrahim, George; Lu, Jyann-Tyng; Peterson, Katie; Vu, Andrew; Gupta, Dr. Sharad; Vullev, Dr. Valentine. “Magnetic Tweezers for Measuring Forces.” University of California Riverside. Bioengineering Senior Design June Startracks Medical, “Serves Business, Education, Government and Medical Facilities Worldside.” American Solution. Startracks.org, Inc. Copyright 2003.