Since the start of the war in Ukraine, the need for prosthetic hands has increased sharply. In Netherlands TU Delft researcher Gerwin Smit has designed a prosthetic hand that can be made through a combination of 3-D printing and laser-cutting, which means that they be produced easily and relatively cheaply in countries that have little money to spend on such things.

These prosthetic hands are already being used in India and now, the Indian technology company Vispala has donated 350 of Smit’s 3D-printed prosthetic hands to war victims in Ukraine, sponsored by the American IT-company, Cisco. Biomechanical engineer Gerwin Smit is the designer of the so-called ‘Hundred Dollar Hand’ which is easy and inexpensive to produce using a combination of 3-D printing and laser-cutting. 80% of people needing a prosthetic hand live in countries which have little money for such things so Smit’s robust and artificial hand offers a robust and reliable solution. Last year, the social enterprise, Vispala made the Hundred Dollar Hand design ready for production and already, several hundred have been made and distributed around India since 2021.
Meanwhile, Gerwin Smit and his team are monitoring the use of these prosthetic hands  and are gathering feedback to see how the design can be made even better.

Source: https://www.tudelft.nl/ 

Nine years after an accident caused the loss of his left hand, Dennis Aabo Sørensen from Denmark became the first amputee in the world to feel – in real-time – with a sensory-enhanced prosthetic hand that was surgically wired to nerves in his upper arm. Silvestro Micera and his team at EPFL Center for Neuroprosthetics (Ecole Polytechnique Fédérale de Lausanne in Switzerland) and SSSA (Italy) developed the revolutionary sensory feedback that allowed Sørensen to feel again while handling objects. A prototype of this bionic technology was tested in February 2013 during a clinical trial in Rome under the supervision of Paolo Maria Rossini at Gemelli Hospital (Italy). The study is published in the February 5, 2014 edition of Science Translational Medicine, and represents a collaboration called Lifehand 2 between several European universities and hospitals.
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“The sensory feedback was incredible,” reports the 36 year-old amputee from Denmark. “I could feel things that I hadn’t been able to feel in over nine years.” In a laboratory setting wearing a blindfold and earplugs, Sørensen was able to detect how strongly he was grasping, as well as the shape and consistency of different objects he picked up with his prosthetic. “When I held an object, I could feel if it was soft or hard, round or square.”

Micera and his team enhanced the artificial hand with sensors that detect information about touch. This was done by measuring the tension in artificial tendons that control finger movement and turning this measurement into an electrical current. But this electrical signal is too coarse to be understood by the nervous system. Using computer algorithms, the scientists transformed the electrical signal into an impulse that sensory nerves can interpret. The sense of touch was achieved by sending the digitally refined signal through wires into four electrodes that were surgically implanted into what remains of Sørensen’s upper arm nerves.

“This is the first time in neuroprosthetics that sensory feedback has been restored and used by an amputee in real-time to control an artificial limb,” says Micera. “We were worried about reduced sensitivity in Dennis’ nerves since they hadn’t been used in over nine years,” says Stanisa Raspopovic, first author and scientist at EPFL and SSSA. These concerns faded away as the scientists successfully reactivated Sørensen’s sense of touch.

Source: https://actu.epfl.ch/