1. Design of Magnetic-Field Concentrators Wednesday February 17th Group: D Mohammedzuned Desai Areio Hashemi Koji Hirota Michael Wong

2. Outline  Introduction  Applications  Objectives  Methods  Results  Conclusion  Future Work  Gantt Chart  References

3. Introduction  What are Magnetic Tweezers (MT)? Scientific instrument used for studying molecular and cellular interactions Scientific instrument used for studying molecular and cellular interactions Ability to apply known forces on paramagnetic particles using a magnetic field gradient Ability to apply known forces on paramagnetic particles using a magnetic field gradient One of the most commonly used force spectroscopy techniques One of the most commonly used force spectroscopy techniques Atomic Force MicroscopyAtomic Force Microscopy Optical TweezersOptical Tweezers

4. Advantages of MT  They do not have problems of sample heating and photodamage that effects optical tweezers  Magnetic forces are orthogonal to biological interactions  Offer the prospect of highly parallel single- molecule measurements Hard to achieve with other single-molecule force spectroscopy techniques Hard to achieve with other single-molecule force spectroscopy techniques

5. Applications  The magnet configurations are relatively easy to assemble Combine force clamp properties with the ability to impose rotation Combine force clamp properties with the ability to impose rotation Ideally suited for the study of DNA topology and topoisomerases Ideally suited for the study of DNA topology and topoisomerases

6. Applications http://www.biotec.tu-dresden.de/cms/fileadmin/research/biophysics/practical_handouts/magnetictweezers.pdf

7. Objectives  Design and fabricate magnetic tweezers that is capable of achieving forces up to 100pN Current design can achieve 2pN Current design can achieve 2pN  Introduce illumination for bright-field transmission microscopy Ibrahim, George et al.

8. Methods  Using Finite Element Method Magnetics (FEMM) to predict the geometries of the magnet and that will produce the largest possible field gradients  Machine and assemble the design that will produce the largest field gradients  Calibrate the magnet so it is ready for data acquisition

9. Rough Design

10. Methods

11. FEMM Methods  Testing for material Iron Iron Mu metal Mu metal  Testing for shape Flat Flat Tip Tip Flat Tip Flat Tip  Testing for optimum distance between two magnets 1 mm 1 mm 3 mm 3 mm

12. FEMM Results ¼ inch 1.5 inch 1/8 inch

13. Results (Material) Iron Mu Metal |B| vs. length |B|/dl vs. length

14. Results (Shape) Tip Flat Tip |B| vs. length |B|/dl vs. length

15. Results (Angle) Double Magnet Tip 2mm Separation Double Magnet Tip 3mm Separation |B| vs. length |B|/dl vs. length

16. Results (Distance) Double Magnet FLAT 1mm Separation Double Magnet FLAT 3mm Separation |B| vs. length |B|/dl vs. length

17. Conclusions  Double flat magnet from mu metal gave best results  If there is a sharp tip there is a huge gradient at the tip but the working distance is not feasible  The distance between the two magnets effects the gradient

18. Future Work  Orders for the magnet cores have been placed When core arrives we can begin fabrication and eventually develop the magnetic tweezers When core arrives we can begin fabrication and eventually develop the magnetic tweezers  Contacted a company regarding the coiling of the magnets  Putting the entire set up together  Design a way for illumination of the sample

19. Progress Chart

20. References  1) 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.  2) Danilowicz, Claudia, Greefield, Derek and Prentiss, Mara. “Dissociation of Ligand- Receptor Complexes Using Magnetic Tweezers.” Analytical Chemistry Vol. 77, No. 10. 15 May. 2005.  3) 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, 2009.  4) 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.  5) Startracks Medical, “Serves Business, Education, Government and Medical Facilities Worldside.” American Solution. Startracks.org, Inc. Copyright 2003.  5) Startracks Medical, “Serves Business, Education, Government and Medical Facilities Worldside.” American Solution. Startracks.org, Inc. Copyright 2003.