Towards variable‐stifness dynamic hand splints based on dielecric elastomer transducers

affected by motor disorders of the hand and having residual voluntary movements of finger can benefit of self-rehabilitation programs to be performed by means of so called dynamic hand splints. These systems consist of orthoses equipped with elastic bands or springs which exert a passive resistance to voluntary elongations of one or more fingers. So, such systems allow for rehabilitation of fingers that still can voluntarily be moved against the recovery force of the counteracting elastic component. Although attractively simple, this approach is limited by the impossibility of modulating the counteracting action in real time. This does not allow for customized training and real-time control, of the rehabilitation exercise, which might desirable to improve the rehabilitation efficacy. To solve this problem, electromechanically active versions of dynamic hand splints are needed. To address this issue with a solution relying on compact and light-weight devices, we are currently studying possible benefits of using dielectric elastomer (DE) transducers as variable- stiffness devices. The transducer is connected to a tendon wire, to be pulled and released by the user, and to a load cell. A processing unit controls the stiffness, so as to train the patient according to desired rehabilitation plans. We show here the current stage of implementation of this concept using a multilayer transducer made of the Danfoss PolyPower DE film.