What prosthetic limbs can do these days is nothing short of miraculous, and can change the life of an amputee in so many ways. But no matter what advanced sensors and actuators are added to the prosthetic, it has to interface with the wearer’s body, and that can lead to problems.
Measuring and mapping the pressure on the residual limb is the business of this flexible force-sensing matrix. The idea for a two-dimensional force map came from one of [chris.coulson]’s classmates, an amputee who developed a single-channel pressure sensor to help him solve a painful fitting problem. [chris.coulson] was reminded of a piezoresistive yoga mat build from [Marco Reps], which we featured a while back, and figured a scaled-down version might be just the thing to map pressure points across the prosthetic interface. Rather than the expensive and tediously-applied web of copper tape [Marco] used, [chris] chose flexible PCBs to sandwich the Velostat piezoresistive material. An interface board multiplexes the 16 elements of the sensor array to a PIC which gathers and records testing data. [chris] even built a test stand with a solenoid to apply pressure to the sensor and test its frequency response to determine what sorts of measurements are possible.
We think the project is a great application for flex PCBs, and a perfect entry into our Flexible PCB Contest. You should enter too. Even though [chris] has a prototype, you don’t need one to enter: just an idea would do. Do something up on Fritzing, make a full EAGLE schematic, or just jot a block diagram down on a napkin. We want to see your ideas, and if it’s good enough you can win a flex PCB to get you started. What are you waiting for?
[Neal Muzzy], a local member of the Cedar Valley Makers makerspace, just made news on Open Bionics for his robotic prosthetic hand called Dextrus v1.2 which he made for his friend, and wounded war veteran, [Taylor].
In just two months, [Neal] worked with his friend to make this robotic prosthetic with the goal of having it more functional and easier to use than [Taylor]’s current prosthetic. The very first prototype was made by using the open-source Dextrus design, to test fit, and control using EMG sensors. Once they determined it would work — onto customizing!
They call it Dextrus V1.2, and it works better for [Taylor] than the original — but that’s the whole point of the Open Hand project — starting with a base design, and making it better. If you’re not familiar with the Open Hand Project, it was originally crowd-funded on Indiegogo, and is now an organization to make robotic prosthetic hands more accessible to amputees. We wrote about it in Hacklet 41 – Prosthetic Projects.
Continue reading “Wounded Soldier Gets Robotic Hand Replacement”
Did you know over 50% of amputees take at least one fall per year due to limited prosthetic mobility? That compares to only about a third of all elderly people over the age of 65!
[Professor Mo Rastgaar] and his PhD student [Evandro Ficanha] set out to fix that problem, and they have come up with a microprocessor controlled prosthetic foot capable of well, to put it bluntly, walking normally.
Working with a scientist from the Mayo Clinic, the pair have created a prosthesis that uses sensors to actively adjust the ankle to create a normal stride. Commercially available prosthetics can do this as well, but can only adjust the foot in an up-down motion, which is fine — if you only plan on walking in a straight line. In addition to having an ankle that can also roll side-to-side and front-to-back based on sensor feedback, they have also moved the control mechanism up the leg using a cable-driven system, which lightens the foot making it easier to use.
We find the test apparatus almost as interesting as the prosthesis itself. The researchers had to come up with a way to measure the performance of the prosthesis when used to walk in an arc. The solution was the turn-table treadmill seen above.
If you have time, check out the video demonstration on the main article’s page which covers the leg and the treadmill build.
This is a screenshot from a video tutorial on making your own prosthetic parts from 2-liter soda bottles. The opaque white part is a mold made of plaster. It’s a representation of the wearer’s limb, and provides the hard, heat-resistant form necessary for this manufacturing technique. You can see the clear plastic soda bottle which fits over the form after the bottom was removed. A heat gun causes the plastic to shrink to the shape of the plaster model.
Once formed, the threaded neck is split down the middle with a band saw. This will receive a piece of 1/2″ PVC pipe to be held in place by the neck and a pipe clamp. It’s possible to stop there, but a second video details an additional bottle used to make the device more rigid. See both videos after the break.
This manufacturing process is aimed at parts of the world that don’t have access to advanced prosthetics. We think it’s a wonderful demonstration of what can be done to improve the lives of amputees. We also think it’s a technique that can be used in other projects… we just haven’t figured out what those are as of yet.
It’s amazing how versatile this plastic waste can be if you put your mind to it.
Continue reading “Learn A New Fabrication Technique From DIY Prosthetics Builders”
After a gruesome accident involving a harvester, [Oscar] lost his legs. [Noel Fitzpatrick] a mad scientist veterinary surgeon came to the rescue. [Oscar] now has leg implants prosthetic feet. It is pretty amazing that a cat would even function in this manner. Have you ever seen one try to walk with tape on its feet? We have to wonder why that cat doesn’t have some more awesome looking legs though. We think that cat needs to team up with [Aimee Mullens], the olympic athlete with no legs, to get a better looking pair.
60 minutes has covered [Dean Kamen]’s modular robotic arm. This thing is light weight, adjustable for different body frame sizes, modular, and eventually thought controlled. The system is currently functioning quite well, as you can see in the video. Current testers are controlling it with buttons under their toes, but the thought control is in the later stages of development. Sounds like science fiction right? You can see a monkey using a thought controlled arm to feed itself grapes, though we don’t think it is [Dean]’s arm.
Another cool feature of this arm is the fact that it changes its grip on your body depending on how much weight you are lifting. Lift something heavy and it grips harder. Though it has a lot of the same information, there is a little bit of different footage in [Dean]’s TED talk about the arm.
It seems to us, with microcontrollers becoming so cheap and accessible that we should be seeing more home made contraptions in this area. Are any of you working with prosthetics?