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Esther Johnson Physics, Del Rio High School Dr. Alvin Yeh, Associate Professor of Biomedical Engineering Dr. Arne Lekven, Associate Professor of Biology

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Noninvasive High resolution 3D Images Two Photon Fluorescence Second Harmonic Generation (SHG) Setup

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Embryos are large, robust and transparent Easily observed Embryonic development occurs rapidly Embryos are easily manipulated

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Yuqiang Bai - Biomechanics Macroscopic Properties of Engineered Tissue Microscopic Properties of Extracellular Matrix Various stretch ratio 1.0:1.0 1.1:1.01.1:1.1 1.2:1.2 1.2:1.1 Photos courtesy of Yuqiang Bai

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Connecting molecular and cellular biology Biomechanics Engineered Tissues Stem cell replacement therapy Cancer research Various other biomedical arenas

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TAKS Science Objective 5 Physics TEKS c.3.E, F c.6.B,E

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Research: focus on biomechanics Correlation Elasticity Hookes law Test the biomechanical properties of engineered skin tissue Photo courtesy of http://hyperphysics.phy-astr.gsu.edu/hbase/permot2.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/permot2.html

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Memory metal spring.wmv

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Hook Activity: Demonstration of Nitinol Spring vs. Regular Spring Ask students why there was a difference Notes on Elasticity and Hookes Law Homework (research assignment) Students must go home and research Nitinol springs

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Elasticity: the property of a substance that enables it to change its length, volume, or shape in direct response to a force effecting such a change and to recover its original form upon the removal of the force (dictionary.com) Hookes Law or Elasticity F = -kx F = restoring force exerted by the spring k = spring constant x = displacement of the spring end from its equilibrium position

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Hookes Law computer simulation Homework: Hookes Law practice problems http://phet.colorado.edu/sims/mass-spring-lab/mass-spring-lab_en.html

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Hookes Law Lab PowerPoint on my summer research experience Photo courtesy of Wikipedia Photo courtesy of JL Stanbrough http://www.batesville.k12.in.us/physics/phynet/mechanics/newt on3/Labs/SpringScale.html

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Stretchiest skin - Guinness World Record2.wmv

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Engineering Challenge: design a mechanism to test the stretch vs. strain on skin-like materials compare the graphs from engineering challenge with graphs from the Hookes Law lab Background: Human Skin Must be elastic If not, it would tear Photo courtesy of exorgroup inc.

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Can synthetic skin handle the same kinds of stressors as its biological counterparts? Human skin is considered viscoelastic meaning it demonstrates both viscous and elastic properties while it is deformed Graph courtesy of http://www.engin.umich.edu/class/bme456/ligten/ligten.htmhttp://www.engin.umich.edu/class/bme456/ligten/ligten.htm

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Students must design a mechanism to compare the various skins to identify which most closely resembles human skin Photos courtesy of http://www.purdue.edu/uns/html4ever/0002.Badylak.SIS.html and http://childrenshospital.org/newsroom/Site1339/mainpageS1339P223.htmlhttp://www.purdue.edu/uns/html4ever/0002.Badylak.SIS.html http://childrenshospital.org/newsroom/Site1339/mainpageS1339P223.html

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The stress/pull on the fabric must be equally distributed over a cross-section Material must be immobilized on the other side Material cannot be torn or the test has failed Students must decide which material presents a stress-strain graph which most closely resembles human skins stress- strain graph.

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Various material squares (wool, spandex, cotton, rubber, leather, etc) Ruler Hanging Mass Set Wood blocks Pulley apparatus Cardboard Masking tape Wire hangers Paper clips

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Post-Test (identical to pretest) Closure/ Discussion

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Students will Be able to manipulate the Hookes Law equation. Analyze and verify Hookes Law. Explore the field of Biomedical Engineering Identify practical applications of physics in engineering Design a Biomechanical testing device Evaluate and rank the biomechanical properties of various materials

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Yuqiang Bai Kirsten Brink