TeachEngineering: Next-Generation Surgical Tools in the Body

Collector: Ann V.

Young engineers design laparoscopic surgical tools in an 11-lesson unit aligned with the Next Generation Science Standards. The first lesson introduces the class to the abdominopelvic cavity. Teams learn what it is like to perform laparoscopic surgery while completing three different tasks and quantify their performance. Next, groups investigate elasticity with a set of springs. They collect data to calculate the spring constant for each spring using Hooke's Law. Another lesson helps learners connect Hooke's law and elasticity with an activity that introduces the class to the behavior of elastic materials. The resource defines stress and strain to calculate the modulus of materials' elasticity and introduces the class to an engineering stress-strain graph. To understand the similarities and differences between elasticity and viscosity, class members investigate four types of fluid behaviors: shear thinning, shear thickening, Bringham plastic, and Newtonian. They then measure the time it takes a marble to fall a specified distance in household fluids. Using unit conversions and algebra, the teams then determine the viscosity of the fluids. Next, future engineers learn about viscoelastic materials and how they differ from solids and fluids. They discover how the molecular structures of the materials relate to their properties, including strain rate dependence, stress relaxation, creep, hysteresis, and preconditioning. It might be silly to determine the creep rate of putty but groups will enjoy making different formulations of silly putty and playing with them to understand how the different mixtures behave. The second part of the activity has groups calculate and compare the creep rate between the silly putty. Pupils learn more about tissue mechanics by reflecting on how silly putty and human tissues are alike. The lesson covers collagen, elastin, and proteoglycans and their effects on body tissues. Moving on, groups explore preconditioning by stretching a balloon to the point of equilibrium. They then measure the force required to stretch the balloon to the same point several times. By graphing the data, they recognize when the force no longer increases. The engineering design process meets laparoscopic surgical robots with an activity that is the last part of the series of 10 and brings all the unit's lessons together. Teams design and build a remotely controlled laparoscopic device. The goal of the device is to search for disease, obtain biopsies, and monitor the process via wireless imaging.

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