Build a Helping Hand *
|Time Required||Average (6-10 days)|
|Material Availability||Readily available|
|Cost||Low ($20 - $50)|
The human body is an impressive piece of machinery, and your hands are no exception. With some training, they can perform delicate and complex tasks like manipulating pens and tools to create art. At the same time, hands have the strength and durability to hold a person's own body weight up on steep rocks. Unfortunately, there is a rapidly growing demand for hand replacements. But fortunately, scientists have studied human anatomy and biology and created human-like hands used as artificial devices called prosthetics.These devices are especially needed in war-torn countries. Land mines (explosive devices concealed under the ground and designed to disable enemy targets ranging from combatants to tanks) are the main cause of devastating limb injuries, leading to an estimated 26,000 amputations per year. Prosthetics help those who have lost their hands to regain functionality, independence, and confidence. Some prosthetic designs mimic the human limb closely, while others use a more innovative, creative approach, like the "Cheetah Flex-Foot blades" used by long distance runners. Recent technological innovations and the dedicated work of biomedical engineers has resulted in remarkable progress, and while modern cutting-edge prosthetic limbs do not quite reach the functionality and/or visual appeal of their human counterparts, they are getting closer every day.
In this science project, you will design and create your own prosthetic hand model and put it to the test. Creating a prosthetic hand that performs all the tasks a human hand can handle is clearly a daunting task, so in this science project you will select only a couple of tasks to work on.
Before you start creating, you might want to do some background research on the anatomy of human hands. Study the musculoskeletal system. How do the sizes of the palm and different fingers compare? What is the role of the muscles, the ligaments, and the tendons in the movement of the finger? What gets pulled to make a finger move? What is the role of the bones or the skin? Next, study some robot hands. The robotics science project Grasping with Straws: Make a Robot Hand Using Drinking Straws or the elbow project referenced in the Bibliography can give you ideas on how to create prosthetic fingers or hands. As you look at these two references, pay attention to one major difference between them; in the case of the straw fingers, strings are only used to flex the finger. The elasticity of the straw is used to let the finger "spring" back to its original position. Rubber bands or springs are other ways to obtain this feature. In the elbow example, different strings are used to flex and extend the body parts, mimicking flexor muscles and extensor muscles. Can you think of some advantages and disadvantages of both ways, and decide which will work best for your prosthesis?
Once you have plenty of information, you will probably be eager to start creating. Before you do so, think of the qualities you would like your prosthetic hand to have. Should it be life-like? What is an acceptable weight and size? Should it be able to pinch something hard so it can hold a pencil or use a computer keyboard? Following the engineering design process, you will use these qualities to define the problem. Then you can create clear and precise design requirements, which will then be used to evaluate and test your prototype. Table 1 lists an example of how a problem translates into design requirements and test criteria.
|Desired Quality||Design Requirements||Test|
||The fingers need:
Now that you have a list of desired qualities for your prosthetic hand, including the design requirements, you can start brainstorming and create a first sketch of the design. Note that the anatomy of a prosthesis does not necessarily replicate the human anatomy, but you may still find that mirroring the anatomical structure of the human hand is a good place to start as you brainstorm for your project. Once your sketch is done, continue following the engineering design process to develop and build a prototype. Figure 1 shows some example designs of prosthetic hands created by Science Buddies staff using drinking straws, rubber washers, polymer clay, upholstery thread and rubber gloves.
Figure 1. Collage of prosthetic hands or fingers created by Science Buddies staff.
As another example, Figure 2 shows a hand made using wood. Many other materials could be used, such as irrigation tubing, rulers for fingers or to create an arm, or hinges from the hardware store or craft store can be handy to create joints. Try using a medical glove (or just its fingers) or skinny balloons (the kind used to make balloon animals) to mimic the skin and increase the hand's grip.
Figure 2. Prosthetic hand made by Science Buddies staff. The thumb has a separate joint from the other fingers so that it can move separately, and has a rubber band in the back to pull its spring back in place.
Once you have made your first model, take a good look. Do you like it? Does it inspire you to make it even better? This is your opportunity to learn. You can move on to the test and redesign step of the engineering design process. Put your hand to the test and record your results. State clearly what worked and what did not work so well, so you or other people can benefit from your findings!
Cite This PageGeneral citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.
Last edit date: 2019-01-12
- Eaton, C. (n.d.). Hand Facts and Trivia. E-Hand. Retrieved September 29, 2014, from http://www.eatonhand.com/hw/facts.htm
- Clements, I.P. (n.d.). How Prosthetic Limbs Work. HowStuffWorks. Retrieved September 24, 2014, from http://science.howstuffworks.com/prosthetic-limb.htm
- Nerdy Science Staff. (2012, April 9). Biomedical Engineering: Elbows and Muscles. Retrieved September 24, 2014, from http://nerdybaby.blogspot.com/2012/04/biomedical-engineering-elbows-and.html
News Feed on This Topic
Materials and Equipment
The materials you will need depend on the design choices you make for your prosthetic hand. Read the Abstract for a few ideas.
Recent Feedback Submissions
|Sort by Date||Sort by User Name|
What was the most important thing you learned?
That the fingers not only need the flesh to be firm yet soft to the touch but to keep other things from getting in and out.
What problems did you encounter?
Can you suggest any improvements or ideas?
Science Buddies materials are free for everyone to use, thanks to the support of our sponsors. What would you tell our sponsors about how Science Buddies helped you with your project?
I thought it was a great idea and I found it helped encourage my love in the field of the human body and medicine.
Overall, how would you rate the quality of this project?
What is your enthusiasm for science after doing your project?
Compared to a typical science class, please tell us how much you learned doing this project.
|Do you agree?||Report Inappropriate Comment|
Ask an ExpertThe Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.
Ask an Expert
If you like this project, you might enjoy exploring these related careers:
Biomedical EngineerShakespeare described humans as a "piece of work," and others have called the body "the most beautiful machine," but like any machine, sometimes body parts need repairs or servicing when the body cannot take care of the problems itself. That's where biomedical engineers come in. They use engineering to solve problems in medicine, such as creating replacement body parts, drug-delivery systems, medical instruments, and test equipment. Their work helps restore health and function, and improves the quality of life for people who are sick or injured. Read more
Civil EngineersIf you turned on a faucet, used a bathroom, or visited a public space (like a road, a building, or a bridge) today, then you've used or visited a project that civil engineers helped to design and build. Civil engineers work to improve travel and commerce, provide people with safe drinking water and sanitation, and protect communities from earthquakes and floods. This important and ancient work is combined with a desire to make structures that are as beautiful and environmentally sound, as they are functional and cost-effective. Read more
Robotics EngineerHave you watched "The Transformers" cartoon series or seen the "Transformers" movies? Both shows are about how good and evil robots fight each other and the humans who get in the middle. Many TV shows and movies show robots and humans interacting with each other. While this is, at present, fantasy, in real life robots play a helpful role. Robots do jobs that can be dangerous for humans. For example, some robots defuse landmines in war-stricken countries; others work in harsh environments like the bottom of the ocean and on the planet Mars. At the heart of every robot is a robotics engineer who thinks about what a robot needs to do and works with several engineering disciplines to design and put together the perfect piece of equipment. Read more
Robotics TechnicianRobots are no longer futuristic machines. Robots are here and now and are used in manufacturing, health care, service industries, and military applications. They perform tasks that are repetitive and hazardous—things that humans don't want to do or are unsafe to do. But robots are still machines, which means they require humans to build, maintain, program, and keep them functioning efficiently. Robotics technicians work with robotics engineers to build and test robots. They are responsible for installing and maintaining robots and keeping them in working order for their employers. If you are interested in working with robots, your future is here and now. Read more
News Feed on This Topic
Looking for more science fun?
Try one of our science activities for quick, anytime science explorations. The perfect thing to liven up a rainy day, school vacation, or moment of boredom.Find an Activity
Explore Our Science Videos
Why Won't it Mix? Discover the Brazil Nut Effect
How to Build an ArtBot
How to Make an Archimedes Screw - STEM Activity