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

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

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

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

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

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

 Research: focus on biomechanics  Correlation  Elasticity  Hooke’s law  Test the biomechanical properties of “engineered skin tissue” Photo courtesy of

Memory metal spring.wmv

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

 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)  Hooke’s 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

 Hooke’s Law computer simulation  Homework: Hooke’s Law practice problems

 Hooke’s Law Lab  PowerPoint on my summer research experience Photo courtesy of Wikipedia Photo courtesy of JL Stanbrough on3/Labs/SpringScale.html

Stretchiest skin - Guinness World Record2.wmv

 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 Hooke’s Law lab  Background: Human Skin  Must be elastic  If not, it would tear Photo courtesy of exorgroup inc.

 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

 Students must design a mechanism to compare the various “skins” to identify which most closely resembles human skin Photos courtesy of and

 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 skin’s stress- strain graph.

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

 Post-Test (identical to pretest)  Closure/ Discussion

 Students will Be able to manipulate the Hooke’s Law equation. Analyze and verify Hooke’s 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

Yuqiang Bai Kirsten Brink