T.E.A.K. Traveling Engineering Activity Kits. Biomechanics of a Joint Activity. Biomedical Engineering Kit: The Biomechanical Hand and Joint

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1 T.E.A.K. - Bioengineering Mechanics of a Joint Lesson Plan 1 T.E.A.K. Traveling Engineering Activity Kits Biomedical Engineering Kit: The Biomechanical Hand and Joint Biomechanics of a Joint Activity

2 T.E.A.K. - Bioengineering Biomechanical Joint Page 2 Instructor Preparation Guide: Biomechanics of a Joint Bioengineering Overview Bioengineering is the use of engineering principles to tackle challenges in the fields of biology and medicine. Bioengineering applies engineering design principles to model any living systems. Biomechanics Overview Biomechanics is the application of mechanical principles to living organisms. Mechanical engineers apply their engineering principles and knowledge of physics and mechanics to simulate living things. Areas of biomechanics that will be cover in this lesson include prosthesis, robotics, and materials. Prostheses helps people with disabilities perform tasks that they could not naturally. Advances in robotics are helping doctors perform surgeries that take a great deal of precision and control. The materials needed for these applications of biomechanics must be selected based on the many different functions and environments a system will be used in. Figure 1 X-Ray of a Human Elbow Figure 2 Robotic Hand with Air Muscles

3 T.E.A.K. - Bioengineering Biomechanical Joint Page 3 Mechanical advantage is a factor in which a simple machine can multiple an input force to overcome a resistance. Many human joints can move in multiple directions, but for this activity we will be focusing on a simple one degree, or direction, of motion, joint, similar to the elbow. A human can lift more than 50 lbs alone in some cases using just the bicep muscle, even though the mechanical advantage is the least. The three orders of mechanical advantages for a lever are shown below. The first order has a mechanical advantage of one, where the output force equals the input force. The second order has as mechanical advantage greater than one, and the third order has a mechanical advantage less than one. Figure 3 X-Ray of a Human Elbow Resistance Pivot Point Force Force Pivot Point MA = Output Force Input Force Resistance The students will be able to experiment with how the mechanical advantage would change if the bicep muscle was located along different points of the forearm. They will be asked to test the different connection points and determine what would be the pros and cons of each scenario. The students will also use different methods to apply a force. This will allow them to act as engineers who are trying to solve a problem by maximizing the effectiveness of a system. Air Muscles Resistance Force Pivot Point Air muscles are operated by compressed air. Air muscles are very lightweight because their main element is a thin membrane, usually made of latex or silicone. This allows them to be directly connected to the structure they power, which is an advantage when considering the replacement of a defective muscle. If a defective muscle has to be substituted, its location will always be known and its substitution becomes easier. This is an important characteristic, since the membrane is connected to rigid endpoints, which introduces tension concentrations and therefore possible membrane ruptures. Another advantage of air muscles is their inherent compliant behavior: when a force is exerted on the air muscle, it "gives in", without increasing

4 T.E.A.K. - Bioengineering Biomechanical Joint Page 4 the force in the actuation. This is an important feature when the air muscle is used as an actuator in a robot that interacts with a human, or when delicate operations have to be carried out. In air muscles the force is not only dependent on air pressure but also on each muscle s inflation, depending on size. This is one of the major disadvantages, because the mathematical model that supports the air muscle functionality is a non-linear system which makes them more difficult to control precisely. However, the relationship between force and extension in air muscles mirrors what is seen in the length-tension relationship in biological muscle systems. There are also other disadvantages: gas is compressible, so an air muscle that uses long tubes must have a control system that can deal with a delay between the movement control signal and the effective muscle action. An air muscle actuator system needs electric valves and a compressed air generator too, both of which are neither light nor small. Muscle Wire A shape memory alloy (SMA, also known as a smart metal, memory alloy, or muscle wire) is an alloy that "remembers" its shape, and can be returned to that shape after being deformed, by applying heat to the alloy. When the shape memory effect is correctly harnessed, this material becomes a lightweight, solid-state alternative to conventional actuators such as hydraulic, pneumatic, and motor-based systems. Shape memory alloys have numerous applications in the medical and aerospace industries. Resources Image Resources Figure 2: Date: February 3 rd, 2009 Time: 1:00 PM Figure 1: ets.com/2007/07/25/tactile-robotic-hand-with-air-muscles/&usg= ST4nIlh4pIeu-wbURJ- hdx-n8aw=&h=1600&w=1200&sz=197&hl=en&start=1&um=1&tbnid=es5- fnvffmumkm:&tbnh=150&tbnw=113&prev=/images%3fq%3drobotic%2bhand%26um %3D1%26hl%3Den Date: February 3 rd, 2009 Time: 12:00 PM

5 T.E.A.K. - Bioengineering Biomechanical Joint Page 5 Activity Preparation Guide - Biomechanical Joint Overview This kit contains activities and discussions for intermediate students to gain a better understanding of how engineers solve complex technical problems and design medical instrumentation to perform intricate medical procedures. This kit demonstrates some of the issues faced by engineers who design and develop mechanical prosthetics to improve the quality of life for individuals with disabilities. The main focus of this kit is a simple, one degree of motion, biomechanical joint. Learning Objectives By the end of this lesson, students should be able to Explain what bioengineering is. Solve an engineering problem. Determine the criteria and constraints and make trade-offs to determine the best decision. Identify alternative solutions based on the constraints of the design. Engineering Connection Engineers work with doctors to create solutions to problems that arise within surgical and medical environments. Due to advancements in surgical operations and in the field of robotics in general, the need for robotic devices that can mimic human joint motion has been increasing over the years. By studying human joint motion, engineers are able to optimize the range of motion a typical person possesses and then apply that range of motion through a mechanical system to carry out a function with great precision and accuracy. Just as an engineer would study, analyze, and model the joint structure of a human elbow, the students participating in this activity will design and construct a simple human joint from common materials and air muscles Activity Descriptions A.) Introduction Discussion: 5 Minutes This discussion will introduce the discipline of bioengineering, and how doctors and people in the medical profession work with engineers to solve technical problems. It will give an overview of the topics that will be covered during this lesson and their applications in a real world setting. B.) Student Engineering Team Roles: Industrial Engineer Plans a process to test joint, collect data, and analyze results with entire engineering team. Test Engineer Collects data throughout experiment.

6 T.E.A.K. - Bioengineering Biomechanical Joint Page 6 Mechanical Engineer Leads assembly of Mechanical Joint Engineering Planner Leads group discussion on improving design C.) Biomechanics of a Joint Activity: 30 Minutes This activity will allow the students to identify an engineering problem and test different solutions. The problem will be creating the motion of a biological joint such as the human elbow. The students will be asked to think of different ways to solve this engineering problem. After this, the students will work in groups as they design and test different solutions to this engineering problem. The students will operate an air muscle and a mechanical system. After they have tested all of the potential solutions and analyzed the data, they will make their decision as to which method to power the joint and which system design creates the best solution. D.) Group Discussion: 5 Minutes This concluding discussion will recap what the students have learned during the group activity. It will further allow the students to participate in a class discussion based around the conclusion that they gathered from conducting the activity as engineers. Students will also hear about new technologies such as telesurgery, where doctors in California can operate on a patient in New York with robotic controls and instruments such as the ones they just built in classroom activity. The discussion will also include how engineers have analyzed inefficiencies with human joint function and how through analysis and design collaboration, they have been able to improve and optimize this human motion. New York State Learning Standards New York State Health Learning Standards a.) Standard 3: Resource Management - Students: Distinguish between invalid and valid health information, products, and services. - Students: Analyze how the media and technology influence the selection of health information, products, and services. New York State Technology Learning Standards a.) Standard 1: Engineering Design -Students will use mathematical analysis, scientific inquiry, and engineering design, as appropriate, to pose questions, seek answers and develop solutions. - Students: Activate devices Recognize why an object or choice is not working properly Recognize how a defective simple object or device might be fixed Under supervision, manipulate components of a simple, malfunctioning device to improve its performance Design a structure or environment (e.g., a neighborhood) using modeling materials such as LEGO Duplo blocks, model vehicles, model structures, etc.) b.) Standard 5: Technological Systems - Students will apply technological knowledge and skills to design, construct, use, and evaluate products and systems to satisfy human and environmental needs.

7 T.E.A.K. - Bioengineering Biomechanical Joint Page 7 - Students: Identify and operate familiar systems Assemble simple systems New York State Science Learning Standards a.) Intermediate Standard 1: Analysis, Inquiry, and Design. - T1.1: Identify needs and opportunities for technical solutions to from an investigation of situations of general or social interest. - T1.1a: Identify a scientific or human need that is subject to a technological solution which applies scientific principles. - T1.3a: Identify alternative solutions base on the constraints of the design. b.) Intermediate Standard 6: Interconnectedness - 1.4: Describe how the output of one part of a system can become the input to other parts : Describe how feedback mechanisms are use in both designed and natural systems to keep changes within desired limits : Determine the criteria and constraints and make trade-offs to determine the best decision. Resources 1.) 2.) 3.) Note: Many of these resources were used in assisting the creation of the following Lesson Plan and we want to thank and reference them for their valuable instruction.

8 T.E.A.K. - Bioengineering Biomechanical Joint Page 8 Biomechanics of a Joint Duration Minutes Concepts covered: Bioengineering Biomechanics Mechanical Advantage Air Muscles Medical Applications

9 T.E.A.K. - Bioengineering Biomechanical Joint Page 9 Bioengineering Discussion: (2 Minutes) Background Information: Bioengineering is the application of engineering principles to address challenges in the fields of biology and medicine. Bioengineering is the application of the principles of engineering design to the full spectrum of living systems. Group Discussion: Bioengineering Background (Pose the following questions to the group and let the discussion flow naturally try to give positive feedback to each child that contributes to the conversation) What do you think bio (biology) means? The study of life and a branch of the natural sciences that studies living organisms and how they interact with each other and their environment. The study of the environment. The study of living organisms and living systems. What do you think engineering is? What do you think it means to be an engineer? A technical profession that applies skills in: o Math o Science o Technology o Materials o Anatomy o Environmental Studies Discuss with the students what bioengineering is and the broad scope of areas that bioengineering includes. For this discussion, provide students with examples of bioengineered products and applications. Bioengineering applies engineering principles in the fields of medicine, biology, robotics, and any other living system. Examples of products that have been bioengineered are: o Prosthetic Joints o Artificial Limbs o Hearing Aids o Artificial Organs Heart, Lungs, Etc. o Dialysis Machines. o Contact Lenses.

10 T.E.A.K. - Bioengineering Biomechanical Joint Page 10 Biomechanics of a Joint Activity Introduction: (5.0 Minutes) Background Information: This kit contains activities and discussions for intermediate students to gain a better understanding of how engineers solve complex technical problems and design medical instrumentation to perform intricate medical procedures. This kit further demonstrates how engineers design and develop mechanical prosthetics to improve the quality of life for individuals with disabilities. The main focus of this kit is a simple, one degree of motion, biomechanical joint. Simplified Definitions: Mechanical Advantage A factor by which a mechanism multiplies the force. The force you get out divided by the force you put in. Telesurgery New technology using a robotic hand, powered by air muscles, that allows a doctor in one location to perform surgery at another location. The doctor wears a glove that transmits his movements to the robotic hand controlled by air muscles. Group Discussion: Biomechanics (5.0 Minutes) This discussion will occur after the introductory discussion and will lead into the Mechanical hand activity. (Pose the following questions to the group and let the discussion flow naturally try to give positive feedback to each child that contributes to the conversation) What is Biomechanics? Application of mechanical principles to living organisms. o Creating a model of a human joint o Prosthesis o Robotics Why would someone need a mechanical limb? To replace a lost or missing limb. To perform a task that cannot be done by a human. Increase strength or motion of a human limb.

11 T.E.A.K. - Bioengineering Biomechanical Joint Page 11 What do engineers need to know to create a mechanical model of a body part? Range of motion Strength Size Location Shape Purpose

12 T.E.A.K. - Bioengineering Biomechanical Joint Page 12 Biomechanical Joint Activity 30 Minutes Learning Objectives By the end of this exercise, students should be able to 1. Discuss their predictions with team members. 2. Work as a team to build an apparatus. 3. Follow a procedure to test predictions 4. Analyze data that has been collected Materials (per group) 1. 1 Biomechanical Joint Worksheet 2. 1 Biomechanical Joint Apparatus Procedure 1. Draw the Second and Third Order Lever from the mechanical advantage schematic on the board and explain what it means. 2. Hand out Worksheet 3. Instruct students to discuss the first three questions within group and come up with answers 4. Hand out Biomechanical Joint Setup 5. Have students put Biomechanical Joint together and perform experiment 6. Have students fill out the rest of the worksheet with their results Expected Results 1. See Worksheet Solutions End Biomechanical Joint Activity

13 T.E.A.K. - Bioengineering Biomechanical Joint Page 13 Mechanical Joint Activity Worksheet What position will require the most muscle force to lift the load, and why? What position will require the least muscle force to lift the load, and why? What position will have the most mechanical advantage? 1. Attach Clamp to desk 2. Attach mechanical joint to clamp 3. Rank each position on the arm in the table below a. Rank Force 1 being the least amount of force required, and 5 being the most b. Rank Length of Rope 1 being the least amount of rope required, and 5 being the most Position a b c d e Force Length of Rope What joints on the human body move the same way as this joint, and can be modeled with this joint? What position would most closely resemble one of these human joints?

14 T.E.A.K. - Bioengineering Biomechanical Joint Page 14 Mechanical Joint Activity Worksheet What position will require the most force applied? Position A What position will require the least force applied? Position E What position will have the most mechanical advantage? Position E 1. Attach Clamp to desk 2. Attach mechanical joint to clamp 3. Rank each position on the arm in the table below a. Rank Force 1 being the least amount of force required, and 5 being the most b. Rank Length of Rope 1 being the least amount of rope required, and 5 being the most Position A B C D E Force Length of Rope What joints on the human body move the same way as this joint, and can be modeled with this joint? Elbow, Knee, fingers, toes What position would most closely resemble one of these human joints? Position A

15 T.E.A.K. - Bioengineering Biomechanical Joint Page 15 Concluding Discussion: (5.0 Minutes) How else could the force be applied? Electric Motor Muscle wire (explain what it is) What muscles could air muscles replace? Any muscle What problems would exist if your bicep was actually attached at your wrist? The muscle would get in the way of your everyday life Your arm would not be able to travel as far If resources available, show video on air muscles.