Evaluation of force, vibration and thermal tactile feedback in prosthetic limbs

While substantial research efforts have been put forth to advance the mechatronics and control of prosthetic hands, little attention has been paid to restoring the sensory functions of tactile feedback to amputees. It is known that the human hand when unable to feel through either disease or induced anesthesia becomes incapable of performing a number of essential dexterous tasks. Therefore, it is proposed that prosthetic hands without these capabilities will be no better. Tactile sensing in the human hand can be used for both autonomous reflexes and conscious perception. In a previous study we had explored using tactile sensing for autonomous reflexes to enable fragile object grasping [1], in this study we evaluate the benefits and performance in conscious perception of force, vibration and thermal tactile information. A prosthetic hand equipped with a BioTac sensor (capable of sensing force, vibration and temperature) and different tactors developed to play back these feedback modalities on a subject's forearm were used to evaluate perception in tactile discrimination experiments. Results showed that this system is able to effectively convey information to the prosthesis user to identify and differentiate objects of different weight, temperature, thermal properties, or surface texture when they were placed between the subject's prosthetic fingertips. While this system was effective at providing useful perceptual feedback, the subject indicated that the majority of the tactors were distracting and would be undesirable for day-to-day use.