Electronics
Walsh’s lab brings together researchers from different disciplines (engineering, industrial design, medicine and business) to develop robotic technologies. These include wearable robotic devices that can help restore and improve mobility in individuals with, for example, gait deficits. One of its major areas of research is in exosuits – soft, wearable robotics designed to improve mobility in people with muscle weakness. The components, which are extremely light, are much more comfortable than traditional exoskeletons and minimise the suit’s interference with the body’s natural biomechanics. The exosuits can also help improve movement in healthy people – one of the lab’s spin-outs, Verve Motion, has launched the SafeLift suit, which reduces the strain on workers performing physically strenuous tasks in different industries. When Walsh and his colleagues decided to create a device that could help with arm movement in people suffering from paralysis, it was, he says, “with broad use across a range of application areas in mind”. Initially, they hoped to use it for stroke rehabilitation. The Covid-19 pandemic prevented them from carrying out human subject testing, however, putting the stroke plans on hold. The team then switched focus to ALS, enabling them to apply for the newly launched Cullen Education and Research Fund (CERF), which awards prizes for research that helps people with ALS lead a more normal life. They went on, in 2022, to win the prize, worth €500,000, in collaboration with the BrainGate team at Brown University.
An inflatable actuator When Tommaso Proietti, an assistant professor at the Biorobotics Institute of Scuola Superiore Sant’Anna, Italy, joined the team as a research fellow, he brought with him expertise in upper limb robotics. Two of his colleagues, Ciaran O’Neill, with a specialism in engineering, and Kristin Nuckols, an occupational therapist, worked with Proietti on the project. Working with clinical and patient communities to understand the requirements and get feedback on early prototypes, the team set about creating the assistive device.
The final prototype, which is powered cordlessly by a battery, consists of a shirt with an inflatable actuator resembling a balloon under the armpit. A sensor system that can detect angle, velocity and acceleration is integrated into the shirt. After a 30-second calibration period in which it detects the strength and mobility of the individual patient, it inflates the balloon accordingly, moving the arm in a way that appears smooth and natural. If, for example, an individual with ALS is normally able to move their arm to 40 or 50 degrees of elevation, once they reach this angle, the robot assists them to raise it further.
Medical Device Developments /
www.nsmedicaldevices.com
Proietti, who spent three years in the Harvard lab working on the technology, says it “seems like a very simple idea to use inflatable balloons to assist the shoulder”. The biggest challenge, he says, was to “understand how to anchor the textile to the body in a smart way that would allow maximising the torque transfer from the pressurised actuator to the limb”. They used a combination of extensible and inextensible textile in the design of the shirt – the inextensible to transfer the torque, and the extensible to make the shirt more comfortable and adjustable to different body sizes. Another challenge was to find a pump that could pressurise the necessary flow, but was not too heavy, bulky or noisy. There are not many companies making pumps for health care. “We were able to find one very exceptional device, that is very silent and provides a good flow,” Proietti says. The team bought three prototypes but were then told that the company would only sell the pumps in batches of at least 100. Fortunately, there has since been a change of heart, and the company is now selling the pumps individually at a cost of about $3,000 each.
The Harvard Biodesign Lab prototype includes infl atable actuators that assist in moving the arm through a higher range of motion than ALS patients can manage.
“[We had] to understand how to anchor the textile to the body in a smart way that would allow maximising the torque transfer from the pressurised actuator to the limb.”
Tommaso Proietti
Significant improvements in function Once the prototype was complete in the summer of 2021, the researchers were able to test it on 10 patients with ALS at different stages of the disease. One advantage they observed was ease of use: participants were able to learn how to use it in under 15 minutes. Despite the relative simplicity of the design, they saw “significant improvements in function”, says Walsh, and patients were able to increase arm movement by 30–40%. As well as
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Harvard Biodesign Lab
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