With the hand: the future of mechanical gloves

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This article originally appeared in Medical Device Developments

A new robotic glove could soon help people suffering from loss of hand motor control regain some of their strength. Oliver Hotham speaks to the project’s head, Conor Walsh, and mechanical engineer Kevin Galloway, about how silicone elastomers are helping medical device designers develop products that are more comfortable and can better mimic nature, and what the research means for the business of medical devices.

For patients suffering from muscular dystrophy, amyotriphic lateral sclerosis (ALS), and spinal injury, it’s the lack of mobility, and the loss of the independence that comes with it, that’s most demoralising and most impacts the quality of everyday life. From picking up a cup to cooking, cleaning or getting dressed, tasks that most take for granted become exhausting.

But a team of pioneering researchers at Harvard might be onto a solution. Working out of the Wyss Institute for Biologically Inspired Engineering and the John A. Paulson School of Engineering and Applied Sciences, they’ve developed a soft robotic glove that, using customisable actuators tailored on a patient-by-patient basis, might give hand-impaired subjects a chance to regain their mobility.

Leading the project is Conor Walsh, an assistant professor of mechanical and biomedical engineering at Harvard with a speciality in developing technology which combines mechanical engineering with human physicality. He’s worked on a soft exosuit which helps soldiers carry heavy loads and allows stroke victims to regain mobility, and is an expert in developing mobility-enhancing technologies that are both comfortable to wear (often a challenge) and powerful.

Panagiotis Polygerinos, an engineer at Wyss and author of a number of papers on these type of devices, built the first benchtop prototype, putting together the technology which would hold the customisable actuators to the hand. But it wasn’t long before the team realised that, to really get to grips with the potentials of the hardware, and understand how to improve its general functionality and customisability, they had to go to the patients that would be using it. The designers then put together of group of participants for tests: recruiting stroke victims, spinal chord injury patients, muscular dystrophy and ALS sufferers, to try it out.

“We really wanted to get their feedback on the design,” says Galloway, when asked why this stage was so essential. “We wanted to find out ‘do you want this? You know, is the range of motions good enough?”

Just fitting the glove to the hand proved a challenge, giving the patients a comfortable experience that directs the forces as best as possible towards bending their fingers, as well as finding the right textiles – the question being how to anchor it to the hand so that it felt comfortable doesn’t get hot and sweaty but can still carry out the complex mechanical tasks required of it.

“So we use breathable materials and, you know, try to create a glove that is easy to put on and take off, allows the hand to breathe and still anchors the actuators to the hand,” says Galloway.

“Basically, we mold silicon tubes or balloons and add specially patterned reinforcements with Kevlar fibres and other inextensible sheets that cause them to take particular shapes when inflated,” argues Walsh. “Normally, when we force air into the silicon tubes, they just expand equally in all directions. But adding the reinforcements allows us to mechanically program the actuators so it gives the desired motion and force when pressurized.”

The other major task was developing how the customer would control the device. Focusing on patients with neuro-muscular disorders, for whom motion is always difficult, coming up with control schemes which can detect user intent was complex and it’s an aspect of the technology that’s still under discussion. But Wyss are pursuing a range of options, including the  use of EMG sensors that detect and anticipate muscle activity.

“We’ve been playing with a whole bunch of different suite solutions to detect user intent,” says Galloway.

The recognition of this fact allowed the technicians at Wyss to really get to grips with the lives of the end-use customers, and the key challenge of the device became clearer as time went on: to balance the highly functional and complex technology with comfort and ease of use. Part of their approach at the institute is the “from bench to bedside” philosophy: a holistic way to go beyond functionality by incorporating the often overlooked social and psychological factors which go into the design of a product like this into the process.

“From the start of this project, we’ve focused on understanding the real-world challenges facing these patients by visiting their homes to perform research,” Walsh explained when the success of the research was first announced back in June.  

Of course, the teams at Wyss aren’t the only engineers developing these types of devices. In October, MIT announced that they had built a three-fingered robotic hand with adaptive sensors, capable of identifying and holding objects. This design is not dissimilar to one developed by researchers at Carnegie Melon, too, with both utilising soft robotics to mitigate the challenges that come with regulating grip in non-human hands.

But in contrast with other engineering departments, which are exploring this in the context of attaching hands to larger robots and artificial intelligence, the focus at Wyss is integrating technology into human biology, in short – the glove must comfortable, affordable, and match the physicality of the wearer.

“We’re not trying to overpower the person,” explains Walsh. “We’re trying to put a light, flexible actuator on them that, in this case, when it’s pressurized, has kind of a similar motion than what they would be trying to do (if they weren’t paralysed), so it works naturally and synergistically with them.”

This is why it must be made of entirely soft materials. For one, they make the device easy to fit and adjust to the human hand, and can be as comfortable as possible.

“Soft robotics is a rapidly growing subfield of robotics, and our application is an example how the technology is useful for applications when robots need to intimately interact with people,” he says. “Our goal is to use soft materials, and this brings a number of benefits. It makes the device very easy to fit and adjust to the human hand, and thus, when assistance is applied, it’s very comfortable for the wearer.”

The main focus was patients who enjoy general motor function but whose situation is, unfortunately, not set to improve in the future:  they can move their arms, but the hand is very weak. The glove isn’t meant or users to be applying huge forces to the hand, it’s intended to help patients with the day to day tasks which limit their independence: picking up small objects, buttoning up a shirt.

“It’s not going to allow you to crush a beer can,” says Galloway. “So for the moment it’s not for the worker on the factory floor lifting heavy objects, it’s for people who have really weak hand strength.”

“So the glove is able to provide enough force to open and close their hand, and provides enough force to pick up some objects of daily living.”

Of course, there’s a long way to go before we see these gloves on sake, and affordability remains a challenge. But what makes the Wyss Institute’s special, however is the emphasis on practicality and commercial viability: Walsh and his team are building technology with the view that, one day, it’ll be accessible to the majority of the population.

“The whole mission of the Wyss Institute is to get technologies and bring them to market,” says mechanical engineer Kevin Galloway. “What’s great about the Wyss is there are a lot of resources, from business development people.”

“The whole idea is to push the technology, put a lot of intellectual property around it, and look for opportunities to commercialize it.”

Walsh argues that Wyss now has a proof of concept device which demonstrates that the technology does indeed help patients grasp objects, but concedes there’s a great deal of work that needs to be done before it’s robust enough for wider use.

“At the moment we have an engineering team focused on refining the technology, which we then hope to do a ten-patient pilot study within a year,” he says. “If we’re successful, then we’ll seek a commercial partner who will then help take the device to market.”

So where does this leave the industry more broadly? Obviously it’s early days, but the ideas behind the project have major implications for at-home rehabilitation. Most of the devices on the market are prohibitively expensive, sometimes the cost of a car, and Wyss, in contrast, is working with materials that are cheap. If the technology becomes widespread, there are countless millions whose lives would be profoundly transformed by the technology.

“It would be wonderful to be able to control my environment a little better, and my life a little better,” a study participant says in a video on the Wyss’s website, an elderly woman suffering from muscular dystrophy, who finds it impossible to pick up day-to-day items.

“With the glove it’s like having a hand back,” she says, smiling. “If anything it feels good to have it on, it feels nice to have my fingers extended, but most of all it’s the function – to have strength in my hand again, it’s just wonderful.”

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