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Elastic Measurements in an Operating Shoe Sole

Elastic Measurements in an Operating Shoe Sole. BME 301 Steven Pauls, Timothy Rand Brian Schwartz, Brant Kochsiek Advisor: Professor Naomi Chesler Client: Professor David Beebe March 5, 2004. University of Wisconsin – Madison Biomedical Engineering Design Courses

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Elastic Measurements in an Operating Shoe Sole

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  1. Elastic Measurementsin an Operating Shoe Sole BME 301 Steven Pauls, Timothy Rand Brian Schwartz, Brant Kochsiek Advisor: Professor Naomi Chesler Client: Professor David Beebe March 5, 2004

  2. University of Wisconsin – Madison Biomedical Engineering Design Courses INTELLECTUAL PROPERTY STATEMENT All information provided by individuals of Design Project Groups during this or subsequent presentations is the property of the University and of the researchers presenting this information. In addition any information provided herein may included results sponsored by and provided to a member company of the Biomedical Engineering Student Design Consortium (SDC). The above information may include intellectual property rights belonging to the University to which the SDC may have l license rights. Anyone to whom this information is disclosed: 1) Agrees to use this information solely for purposes related to this review; 2) Agrees not to use this information for any of her purpose unless given written approval in advance by the Project Group, the Client / SDC, and the Advisor. 3) Agrees to keep this information in confidence until the University and relevant parties listed in Part (2) above have evaluated and secured any applicable intellectual property rights in this information. 4) Continued attendance at this presentation constitutes compliance with this agreement.

  3. Problem Statement • Device should fit into the sole of a shoe • Inform runner when shoe is worn • Decrease incidence of injury due to shoe wear • Measure the elasticity of the shoe sole • Direct measurement • Other methods

  4. Problem Motivation • Running shoes last 300-500 miles • Worn shoes not always “worn” • Incidence of injury increases with worn shoes • Diagnostic tool in relation to running style

  5. Client Requirements • Lightweight • Ergonomic with sole • Operable for life of the running shoe • Should not hinder performance • Have clear indicator

  6. Elastic Effect • Elastic recoil cushions impact • Age/Wear decreases elastic effect • Similar stresses create more strain on material

  7. Shoe Materials • Ethylene and Vinyl Acetate (EVA) • Polyurethane (PU) Upper Footbridge Midsole Outsole http://www.dummies.com/WileyCDA/DummiesArticle/id-450,subcat-SPORTS.html

  8. Pronation Styles Wet sand imprints indicating foot shape and pronation style Most common strides (note: underpronation is also termed supination) http://www.dummies.com/WileyCDA/DummiesArticle/id-450,subcat-SPORTS.html

  9. Shoe Wear Patterns • Forefoot Striking • Neutral • Overpronation • Supination http://www.fleetfeethouston.com/tips/basics.asp

  10. Principles Design Matrix

  11. Strain Gauge • Directly affected by elasticity (ε = σ∕ E) • Inexpensive • Small • Requires calibration • Incorrect alignment http://www.dur.ac.uk/richard.scott/gauges.html

  12. Conductive PolymerForce Sensor • Resistive elements • Medium to high pressure range • Compact • Indirect Measurement • Requires calibration http://interlinkstore.com

  13. Force Differential • Impact creates force (F), smaller dispersal force (f) • F α f as a function of shoe sole force absorbance • Force absorbance during impact is a function of elasticity • Set ratio F:f will trigger sensor, indicate elastic wear

  14. Retroreflectors • Advantages • Small, lightweight, & cheap • Only taking one measurement (distance) instead of two • Virtually no wear on device • Disadvantages • Need for clear polymer in some portions of the shoe sole • Distance measurement may not correlate to shoe sole elasticity

  15. Future Work • Polymer which degrades faster than EVA or polyurethane • Integrate retro-reflector, strain gauge, & a conductive polymer force sensor into polymer mold • Perform tests to determine which device is able to detect wear (elasticity) the best • Determine correlation between shoe wear and output of each device • Select ultimate wear value • Integrate chosen device into a shoe sole for field testing • Possible patent application

  16. Prototype Design Matrix

  17. Acknowledgments Professor Naomi Chesler Professor David Beebe Professor John Webster UW Biomedical-Engineering Dept.

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