1. Local Piezoelectric Response and Elastic Properties as Measured with AFM Emily Smith eas48@drexel.edu Advisor: Dr. Spanier

2. Problem Statement Techniques to measure local properties of bone Correlation with hierarchical structures Piezoelectricity connection with bone growth

3. What is Bone? CollagenProteinHydroxyapatite Ca-phosphate mineral Types –Cortical –Cancellous http://silver.neep.wisc.edu/~lakes/BME601.html

4. Bone Hierarchical Structure Rho, Jae-Young, Liisa Kuhn-Spearing and Peter Zioupos. Mechanical properties and the hierarchical structure of bone. Mechanical Engineering & Physics. 20 (1998) 92-102.

5. Bone Cells Osteoclasts –Breaks down and removes bone material Osteoblasts –Forms new bone material Osteocytes –Senses problems and pressure in the bone http://depts.washington.edu/bonebio/bonAbout/bonecells.html nucleus Multiple Nuclei

6. Microscope Image of Bone Cells http://depts.washington.edu/bonebio/bonAbout/bonecells.html

7. Principle of AFM http://www.npl.co.uk/smd/npl_research/afm_theory.html

8. Atomic Force Microscopy Scan probe microscopy Three Topographic Modes –Contact –AC Intermittent –AC Non-contact www.asylumresearch.com

9. Force vs. Tip-Sample Separation C- Contact IC – Intermittent Contact NC – Non-contact Catalin Harnagea. Local piezoelectric response and domain structures in ferroelectric thin films investigated by voltage-modulated force microscopy. Ph.D. thesis. 2001

10. Piezoelectricity Piezoelectric –Mechanical Stress => Electric Field Equation: D = d * σ –Converse Piezoelectric Effect Equation: x = d * E Ferroelectric –Spontaneous Dipole Moment –Domains

11. Elasticity Ratio of stress and strain Ability to return to its original shape Current ways to measure Strain Stress Elastic Range Strength http://hotmix.ce.washington.edu/wsdot_web/Modules/04_design_parameters/04-2_body.htm#elastic_modulus

12. Piezoresponse Scan Principle AC voltage Conductive Tip Contact Mode

13. Scan of Sample: Lamella of Cortical Bone Line cross-section of scan: Shows height Single Lamella Rho, Jae-Young, Liisa Kuhn-Spearing and Peter Zioupos. Mechanical properties and the hierarchical structure of bone. Mechanical Engineering & Physics. 20 (1998) 92-102.

14. Example of Piezoresponse Scan a- Topographic image of a Bi 4 Ti 3 O 12 grain (line added) b- The domain structure Catalin Harnagea. Local piezoelectric response and domain structures in ferroelectric thin films investigated by voltage-modulated force microscopy. Ph.D. thesis. 2001

15. Piezoelectric Response in Bone (a)Topography (b)/(c) Piezoresponse Scan C. Halperin, S. Mutchnik, A. Agronin, M. Molotskii, P. Urenski, M. Salai, and G. Rosenman. Piezoelectric Effect in Human Bones Studied in Nanometer Scale. Nano Letters. 4 (2004) 1253-6.

16. Future Work Piezoelectric Response Piezoelectric coefficient Elasticity measurement

17. Literature Jae-Young Rho, Liisa Kuhn-Spearing and Peter Zioupos. Mechanical properties and the hierarchical structure of bone. Mechanical Engineering & Physics. 20 (1998) 92-102. Catalin Harnagea. Local piezoelectric response and domain structures in ferroelectric thin films investigated by voltage- modulated force microscopy. Ph.D. thesis. 2001 C. Halperin, S. Mutchnik, A. Agronin, M. Molotskii, P. Urenski, M. Salai, and G. Rosenman. Piezoelectric Effect in Human Bones Studied in Nanometer Scale. Nano Letters. 4 (2004) 1253-6. http://silver.neep.wisc.edu/~lakes/BME601.html http://depts.washington.edu/bonebio/bonAbout/bonecells.html http://www.npl.co.uk/smd/npl_research/afm_theory.html www.asylumresearch.com http://hotmix.ce.washington.edu/wsdot_web/Modules/04_design_pa rameters/04-2_body.htm#elastic_modulus