She injured a finger in her right hand in October 2010 and severe pain spread throughout her arm. Doctors diagnosed her with complex regional pain syndrome in early 2011 before the condition worsened, her limb twisting up towards her chest. Finally, on 24 November 2014, her right hand and wrist were amputated.
With the loss of her dominant hand, her independence – and long-held flower arranging business plan – went as well. At a rehabilitation centre two months after the amputation, she was offered a plastic, cosmetic replacement, or nothing.
A cosmetic prosthetic limb (Credit: Shutterstock)
Choosing nothing, and facing prohibitive costs for more advanced prostheses, she went more than three years without a replacement – until she spotted an online post about Mitt. She contacted the company and they visited her soon after, bringing a brand-new prosthetic hand. After attaching it herself, Sam tried some drawing exercises.
“I couldn’t believe it,” she says. “I picked up the pen straight away, put the adapter to the hand and just used it, and there was no pain. It just felt natural.”
The device returned the independence lost years earlier, she says. “I hadn’t used a knife in years… I could go to a restaurant and not have to ask my husband or children to cut my food.”
But the prosthesis was not some hyper-advanced bionic limb using a complex combination of actuators, sensors and algorithms. Instead, it took its cues from comfortable sportswear, had minimal parts and was optimised for simple, cheap manufacturing. Its creators hope it can change millions of lives for the better.
‘A completely new type of prosthetic’
Mitt began two years ago as a project from four self-confessed “nerdy engineering students” at Imperial College London. Studying mechanical engineering, the team decided to focus on robotics.
“We had seen prosthetics in the media and they look very high-tech, like Luke Skywalker’s hand,” said Mitt founder Nate Macabuag after winning the People’s Choice Award at the recent Royal Academy of Engineering Enterprise Hub Launchpad Competition. Shortly after the project began, however, a meeting with quadruple amputee Alex changed their perceptions.
“The reality is, people still get given the same kind of design from World War Two – hooks, big rigid plastic you just jam yourself into. They are really uncomfortable to use, really heavy, really horrible to use and also restrictively expensive.”
The team soon realised they needed to abandon the high-tech robotic route for their work to have the biggest impact. “The basis of the technology has been simplified over the course of the project,” Nate says. “There are very simple things we can do now before we focus on pushing the frontier, the next generation of prosthetics.”
Nate with a Mitt prosthetic. The attachment is designed for carrying objects by hooking onto them (Credit: Mitt)
Prosthetic arms and legs are often made of two parts, he explains – the socket, which is worn by the user, and a device such as a replacement hand or foot on the end. With no device attached, the Mitt socket resembles sportswear, with a flexible sleeve as its base and rigid supports to give it structure and transmit loads from the user to the end device. A user slips the socket on like a sleeve and tightens it using two small buttons, before clipping an interchangeable tool on to the socket.
“The innovation isn’t actually any new science, it’s a culmination of elements from other industries – sportswear, shoe design, cycling – that when brought together result in a completely new type of prosthetic design,” says Nate. “More like stylish sports clothing and less like a rigid, horrible medical device.”
The modular design allows for great flexibility. The team has built attachments for carrying pens, kitchen knives, cutlery and drinking glasses, and there are plans for 15 more designs. Nate also hopes the company will eventually reactively meet the needs of many more of the roughly 5m upper-limb amputees worldwide. “When people suggest an idea to use, we hear it and we add that module,” says Nate. “The idea is always to be working on new ones.”
A helping hand
The Mitt approach is a radically different engineering process from most high-profile prosthetic projects, which often dazzle with dexterity and flexibility but come with prohibitive prices or impractical commercialisation periods. According to Eureka!, most multi-grip bionic hands cost between £25,000 and £60,000 in the UK. A cheaper option is Open Bionics’ Hero Arm, which is custom made and controlled by users’ muscles. It can nonetheless cost up to £10,000 and is not yet available on the NHS.
Mitt, however, aims to release a significantly cheaper product. “We are talking the price of a pair of shoes rather than a car,” says Nate. The simple design should allow cost-effective manufacturing, which should make the device accessible for many more of the millions of people with missing limbs.
The award-winning company aims to open a simple website for people to buy its products this year, with a launch for low-to-middle income countries in 2020. The former students aim to start mass manufacturing in China after that.
As with everything the company does, however, the expansion plan is built around flexibility. The team is already working with international charities, and aims to use networks in countries such as India to distribute its devices – and to find out what users think.
“What we really want to do is keep the feedback loop really close, so we are not just sending limbs off to some country and not listening to what people want,” says Nate. “We are both engineers, me and Ben [the firm's co-founder Ben Lakey], so we are doing this to be useful. We had a product that we thought could be useful, that is what drives us. Starting a company is very much secondary to helping people.”
The dedication to practicality over complexity at all costs is admirable, and appreciated by trial user Sam Gibson. “There are so many things out there, but they are so expensive,” she says, before providing testimony for Nate’s recent award win. “They are going about things the right way. They are two lovely lads who want to help people.”
Although it can be tempting for engineers to chase an elusive target in the search for cutting-edge technology solutions, Mitt spoke to Sam and more than 100 other people with limb loss. The key problems were uncomfortable replacement limbs and high costs, so the team focused on those issues. If they achieve their goal of helping millions worldwide following their initial success, their approach could be an inspiration for new generations of young engineers.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.