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Development of a Full Field Optical System for Characterization of Fresh Biomaterials

Development of a Full Field Optical System for Characterization of Fresh Biomaterials. Megan Bland, Marisol Cortes, Kristin Solt Advisors: Dr. Yang and Dr. Siadat 6/26/2009. Outline of today's presentation. Research Objectives Scope of the medical problem Mechanical Properties

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Development of a Full Field Optical System for Characterization of Fresh Biomaterials

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  1. Development of a Full Field Optical System for Characterization of Fresh Biomaterials Megan Bland, Marisol Cortes, Kristin Solt Advisors: Dr. Yang and Dr. Siadat 6/26/2009

  2. Outline of today's presentation • Research Objectives • Scope of the medical problem • Mechanical Properties • Anatomy of Human Bone • Current Methods and Limitations • Digital Image Correlation • Methods and Set-Up • Future Work

  3. Research Objectives • Develop a robust non-contacting system using Digital Image Correlation to measure the stress and strain of fresh bone • Determine material properties of fresh bone • Investigate the effect of drying on the material properties of bone Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  4. Scope of Medical Problem • Over 25% of Americans have musculoskeletal condition requiring medical attention (www.aaos.org) • $849 billion spent annually on bone and joint health (www.aaos.org) • Over 1 million hip and knee replacements in 2006 (www.aaos.org) • 10 million Americans with osteoporosis (www.nof.org) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  5. Knowing the mechanical properties of bone is useful for many medical applications • Better understand normal physiological loading, effects of aging, disease, drugs (M.M. Barak et al.) • Recognize areas of peak stress most likely to fracture (M.M. Barak et al.) • Better design of biomaterials (A. Sharir et al.) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  6. Stress:σ = Mechanical Terminology F Force Area Area Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  7. Mechanical Terminology l - l0 l Change in Original Length Original Length = l lo lo l Strain: ε = Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  8. Mechanical Properties σ ε = Stress Strain Elastic Modulus: E = • Tendency to be elastically deformed www.bwog.net www.townsend.co.uk • Low E • Easily deformed • High E • Difficult to deform Objectives Scope www.tosnend.co.uk Mechanics Anatomy Current Methods DIC Methods Future Work

  9. F Y X Mechanical Properties -εx εy = Poisson’s Ratio: ν= -εtrans εaxial Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  10. Stress-Strain Curve Elastic Modulus Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  11. Stress-Strain Curve Strain (ε) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  12. Bone Anatomy www.medical-dictionary.thefreedictionary.com Trabecular Bone Cortical Bone www.feppd.org http://www.engr.iupui.edu/~turnerch/biomech.htm Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  13. The unique characteristics of bone make whole-field measurement on fresh bone optimal Complex architecture and geometry (A. Sharir et al.) Inhomogeneous (M.M. Barak et al.) Anisotropic (C.H. Turner and D.B. Burr) Graded (A. Sharir et al.) Viscoelastic (A. Sharir et al.) Mineralized (Zaslansky et al.) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  14. Drying Effects Material Properties Brittle Ductile (Yawen Li) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  15. Current Methods • Mechanical w/ Strain Gauge - Tensile Test - 3 or 4 Point Bending • Numerical - Finite Element Analysis • Optical - Digital Speckle Pattern Interferometry - Digital Image Correlation Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  16. Mechanical Tests tensile test 3 point bending www.ptli.com www.insitron.com Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  17. Strain Gauge www.kin.hs.iastate.edu www.answers.com Common method Point specific Inexpensive Need dry sample Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  18. Limitations of Strain Gauge (L.X.Yang) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  19. Finite Element Analysis B. Mahaisavariya, K. Sitthiseripratip, J. Suwanprateeb Algorithm based Node specific Whole system analysis Sample independent Requires input of material properties and experimental validation Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  20. Overview of Optical Methods • Characterize whole surface • Non-contact • More precise and accurate • Examples: Digital Speckle Pattern Interferometry, Digital Image Correlation Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  21. Digital Speckle Pattern Interferometry Fringe Pattern (L.X.Yang) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  22. Example of DSPI (L.X.Yang) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  23. Advantages and Limitations of DSPI • High resolution • High measuring sensitivity—accurate to 30 nm • Very sensitive to vibrations • Can only measure small displacements • Can’t measure contour easily Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  24. Digital Image Correlation • Measures displacement by tracking the gray level distributions in small subsets before and after loading (L.X.Yang) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  25. DIC Theory (L.X.Yang) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  26. Digital Image Correlation (L.X.Yang) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work Two cameras make it possible to measure contour and displacement in three dimensions.

  27. DIC Calibration • Needed to establish parameters such as focal length and camera position and to eliminate distortions dantecdynamics.com Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  28. Results of DIC (L.X.Yang) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  29. Why DIC is Our Chosen Method • Less sensitive to “noise” • Able to detect rigid body motion • Able to measure large deformations • Able to measure 3D contour and strain concurrently • Able to measure dynamic loads efficiently Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  30. Previous Studies • DIC used to characterize mechanical behavior of arterial tissue (Zhang) • DIC used to study loosening of total hip replacements (Zhang) • DIC used to measure strain of wet bone callus (M.S. Thompson et al.) Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  31. Methods • Use DIC to measure strain of chicken tibia in Phosphate Buffered Saline Solution • Apply force and stabilize sample with loading system • Measure force with load cell Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  32. System Schematic Load Cell Istra 4D Software Loading System Cameras Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  33. Whole System

  34. Loading System Design Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  35. Loading System Design Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  36. Load Cell Summary • Capacitance Based technology • True USB connection http://www.loadstarsensors.com/iloaddigital.html Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  37. Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  38. Learning the Software for DIC 1. Focus Image Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  39. 2. Calibrate the Image Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  40. 3. Take a picture of the object. Load the object and take another picture Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  41. 4. Evaluate the Image Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  42. Evaluation of Results • Capture whole surface strain-field image • Generate stress-strain curve • Calculate Elastic Modulus and Poisson’s Ratio • Validate accuracy of results using statistical methods Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  43. Completed Work • Literature Review • Design and build loading system • Obtain load cell • Write output software Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  44. Future Work • Test chicken bone using DIC • Calculate material properties • Investigate difference between dry and wet bone Objectives Scope Mechanics Anatomy Current Methods DIC Methods Future Work

  45. Acknowledgements • We appreciate the: • funding support from NIH 34586 • assistance from Sijin Wu in our load system design

  46. Questions?

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