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Design of Magnetic Field Concentrators
By: Mohammed Zuned DesaiKoji Hirota
Michael WongAreio 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 FEMM General Design Proper 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) Angle 2) 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 Problem2) Experimentations
BudgetComponent Price (US) In Stock
Electromagnetic Magnets $20-$50 each Yes
Magnet Power Supply $200 Yes
Aluminum plate $50-$200 No
Steel Rods (0.5inch diameter)
$50-$100 each No
CCD Camera $1,000-$10,000 Yes
Microscope $30,000-$40,000 Yes
Super paramagnetic beads $100-$500 Yes
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 2008.
• Danilowicz, Claudia, Greefield, Derek and Prentiss, Mara. “Dissociation of Ligand-Receptor Complexes Using Magnetic Tweezers.” Analytical Chemistry Vol. 77, No. 10. 15 May. 2005.
• 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. <http://patft.uspto.gov>. January 6, 2009.
• 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 2009.
• Startracks Medical, “Serves Business, Education, Government and Medical Facilities Worldside.” American Solution. Startracks.org, Inc. Copyright 2003. <http://images.google.com/imgres?imgurl=http://www.startracksmedical.com/supplies/invertedmicroscope.jpg&imgrefurl=http://www.startracksmedical.com/supplies.html&usg=__butCY2zWJa7nAkwkjiPxX_mFy0=&h=450&w=450&sz=24&hl=en&start=2&um=1&tbnid=XH6gnQuJLS7bRM:&tbnh=127&tbnw=127&prev=/images%3Fq%3Dinverted%2Bmicroscope%26hl%3Den%26sa%3DN%26um%3D1>