Flex PCBs Make Force-Mapping Pressure Sensor for Amputee

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?

The Cyborgs Among Us: Exoskeletons Go Mainstream

Every technological advancement seems to have a sharp inflection point, a time before which it seems like any early adopters are considered kooks, but beyond which the device or service quickly becomes so mainstream that non-adopters become the kooky ones. Take cell phones, for example – I clearly remember a news report back in the 1990s about some manufacturers crazy idea to put a digital camera in a phone. Seemingly minutes later, you couldn’t buy a phone without a camera.

It seems like we may be nearing a similar inflection point with a technology far more complex and potentially far more life-altering than cameras in cell phones: powered exoskeletons. With increasing numbers of news stories covering advancements in exoskeletal assistants for the elderly, therapeutic applications for those suffering from spinal cord injuries and neurodegenerative diseases, and penetration into the workplace – including the battlefield – as amplifiers of human effort, it’s worth taking a look at where we are with exoskeletons before seeing someone using one in public becomes so commonplace as to go unnoticed.

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Artificial Limbs And Intelligence

Prosthetic arms can range from inarticulate pirate-style hooks to motorized five-digit hands. Control of any of them is difficult and carries a steep learning curve, rarely does their operation measure up to a human arm. Enhancements such as freely rotating wrist might be convenient, but progress in the field has a long way to go. Prosthetics with machine learning hold the promise of a huge step to making them easier to use, and work from Imperial College London and the University of Göttingen has made great progress.

The video below explains itself with a time-trial where a man must move clips from a horizontal bar to a nearby vertical bar. The task requires a pincer grasp and release on the handles, and rotation from the wrist. The old hardware does not perform the two operations simultaneously which seems clunky in comparison to the fluid motion of the learning model. User input to the arm is through electromyography (EMG), so it does not require brain surgery or even skin penetration.

We look forward to seeing this type of control emerging integrated with homemade prosthetics, but we do not expect them to be easy.

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Dexterity Hand is a Configurable Prosthetic Hand

One of the interesting benefits of the 3D printing revolution is the dramatic increase in availability of prosthetics for people with virtually any need. With a little bit of research, a 3D printer, and some trial and error, virtually anyone can build a prototype prosthetic to fit them specifically rather than spend thousands of dollars for one from a medical professional. [Dominick Scalise] is attempting to flesh out this idea with a prosthetic hand that he hopes will be a useful prosthetic in itself, but also a platform for others to build on or take ideas from.

His hand is explained in great detail in a series of videos on YouTube. The idea that sets this prosthetic apart from others, however, is its impressive configurability while not relying on servos or other electronics to control the device. The wearer would use their other hand to set the dexterity hand up for whatever task they need to perform, and then perform that task. Its versatility is thanks to a unique style of locks and tensioners which allow the hand to be positioned in various ways, and then squeezed to operate the hand. It seems like a skilled user can configure the hand rapidly, although they must have a way to squeeze the hand to operate it, or someone will need to develop an interface of some sort for people without needing to squeeze it.

To that end, the files for making your own hand are available on Thingiverse. [Dominick] hopes that his project will spark some collaboration and development, using this hand as a basis for building other low-cost 3D printed prosthetics. There are many good ideas from this project that could translate well into other areas of prosthetics, and putting it all out there will hopefully spur more growth in this area. We’ve already seen similar-looking hands that have different methods of actuation, and both projects could benefit from sharing ideas with each other.

Thanks to [mmemetea] for the tip!

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Bird Beats Cancer With The Help Of A 3D-Printed Prosthetic

It’s a reasonable certainty that 3D-printing is one day going to be a huge part of medicine. From hip implants to stents that prop open blood vessels to whole organs laid down layer by layer, humans will probably benefit immensely from medical printing. But if they do, the animals will get there first; somebody has to try this stuff out, after all.

An early if an unwilling adopter of 3D-printed medical appliances is [Jary], a 22-year-old Great Pied Hornbill, who recently received a 3D-printed replacement for his casque, the large, mostly hollow protuberance on the front the bird’s skull leading out over the upper beak. There’s no known function for the casque, but it had to be removed since cancer was destroying it and [Jary] wouldn’t have fared well post-surgically without one. Working from CT scans, the veterinary team created a model of the casque as well as a jig to guide the saw during surgery. There’s no word on what filament was used, but we’d guess PLA since it’s biocompatible and available in medical grades. The video below shows some of the surgery; it’s interesting to note that the prosthetic started out natural colored but quickly turned yellow as [Jary] preened with oils from glands near his tail feathers, just like a natural casque would.

Hornbills live to about 40 years old, so [Jary] is just middle-aged. Here’s hoping that he lives a long, happy life in return for being a pioneer in 3D-printing for medical and surgical appliances.

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DIY Socket for Prosthetics Contains Power Supply, Charger

Innovation in prosthetics is open to anyone looking to enhance the quality of life, but there’s an aspect of it that is sometimes under-served. The DIY Prosthetic Socket entry to the Hackaday Prize is all about the foundation of a useful prosthesis: a custom, form-fitting, and effective socket with a useful interface for attaching other hardware. While [atharvshringaregt] is also involved with a project for a high-tech robotic hand with meaningful feedback, socket fitting and design is important enough to be its own project.

The goal is not just to explore creating these essential parts in a way that’s accessible and affordable to all, but to have them include a self-contained rechargeable power supply that can power attachments. Thoughtful strap placement and a power supply design that uses readily available components with a 3D printed battery housing makes this DIY prosthetic socket a useful piece of design that keeps in mind the importance of comfort and fitting when it comes to prosthetics; even the fanciest robot hand isn’t much good otherwise.

Rapidly Prototyping Prosthetics, Braille, and Wheelchairs

We live in an amazing time where the availability of rapid prototyping tools and expertise to use them has expanded faster than at any other time in human history. We now have an amazing ability to quickly bring together creative solutions — perfect examples of this are the designs for specialized arm prosthetics, Braille printing, and custom wheelchair builds that came together last week.

Earlier this month we published details about the S.T.E.A.M. Fabrikarium program taking place at Maker’s Asylum in Mumbai. The five-day event was designed to match up groups of makers with mentors to build assistive devices which help improve the condition of differently-abled people.

The participants were split into eight teams and they came up with some amazing results at the end of the five-day program.

Hands-On: Prosthetic Designs That Go Beyond

Three teams worked on projects based on Bionico – a myoelectric prosthesis

DIY Prosthetic Socket – a Human Machine Interface : [Mahendra Pitav aka Mahen] lost his left arm during the series of train bomb blasts in Mumbai in 2006, which killed 200 and injured over 700 commuters. He uses a prosthetic arm which is essentially a three-pronged claw that is cable activated using his other good arm. While it is useful, the limited functionality restricted him from doing many simple things. The DIY Prosthetic socket team worked with [Mahen] and [Nico Huchet] from MyHumanKit (who lost his right arm in an accident 16 years back), and fabricated a prosthetic forearm for [Mahen] with a modular, 3D printed accessory socket. Embedded within the arm is a rechargeable power source that provides 5V USB output at the socket end to power the devices that are plugged in. It also provides a second port to help recharge mobile phones. Also embedded in the arm was an IR reflective sensor that can be used to sense muscle movements and help trigger specific functions of add-on circuits, for example servos.

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