People usually wear gloves for warmth or protection. There are gloves with other purposes, however, such as restoring mobility to the wearer's fingers. This is the idea behind a mechatronic orthosis called the exomotion® hand one. The exomotion® hand one is worn like a glove and consists of custom-fitted exo-finger mechanics, a supporting forearm splint, a sensor, a control unit, and four miniature drives that provide the power to open or close the wearer's fingers. Six types of grip are available, to restore to the wearer the freedom of movement he or she may have lost as a result of a stroke, accident, or degenerative disease.
The hand orthosis was developed by two medical engineers, Dominik Hepp and Tobias Knobloch. They first met in university, where they both focused on this issue, and finally founded a start-up, HKK Bionics, in 2017. The two men hope to close a gap with their development: “We offer patients with fully or partially paralyzed hands an aid than helps them to perform everyday tasks on their own again,” explains Dominik Hepp. The sort of activities he means include simple tasks like cooking, carrying shopping bags, and opening packages. “With an aid that is suitable for everyday use, these people can regain a degree of independence in their daily lives.”
However, the designers had a number of challenges to overcome before arriving at the latest version of their bionic orthosis. The product is intended to be worn all day long, so it needs to be robust, high-performing, and lightweight. After developing the initial prototype, the main focus therefore was on making the orthosis smaller, which involved finding suitable new components. “That was a real challenge, since we couldn't accept any compromise in terms of stability or performance,” says Dominik Hepp. To solve this problem, the two designers collaborated with suppliers to develop special components. Four customized EC motors from maxon are at the core of the hand orthosis. These motors need to be small but powerful, and they must guarantee years of service with hundreds of thousands of operating cycles. The brushless micromotors supply the necessary grip strength and are controlled via sensors that respond to still-intact muscles, a principle that is also used in prosthetic arms.
“We want to make the exomotion® hand one accessible to as many patients as possible. That's why we are pursuing collaborative partnerships with selected medical supply stores while expanding our network to include doctors and therapists,” explains Dominik Hepp. HKK Bionics now has seven supply partners and two clinical partners, with ten more supply partners to follow in the near future. For the two young businessmen, this is an exciting challenge at the interface between technology and human beings. “It's great to see that with our experience, plenty of creativity, and some tinkering around, we can contribute to improving the quality of patients' lives.” And a successor to the exomotion hand one is already being developed.