There is a recent report [1] of an amputee with a bionic hand being able to feel texture and shape of objects in his grasp. This was a month long test in Italy that has encouraged researchers on the ability to have control of the hand. Typically, there has been no sensation with the prosthesis and the user (wearer) could inadvertently crush objects instead of being able to hold or lift them. There has been previous work that has connected prosthesis to a person nerves and enabled control and movement of the prosthesis, but the fine control has not been available.
The announcement released February 5, 2014 indicated that the study was led by Micera and Stanisa Raspopovic and colleagues at Switzerland’s Ecole Polytechnique Fédérale de Lausanne (EPFL) and the BioRobotics Institute in Pisa, Italy. The scientist claim that this is the first time that an amputee had real-time sensory feeling from the prosthetic. An interesting result was that even though the amputee had lost his hand over a decade previously, the sense of touch was reactivated.
The patient was blindfolded and had earplugs to test the capability of the artificial hand. He was able to distinguish between a mandarin orange and a baseball. He could also feel whether he was holding soft tissue, a hard piece of wood, or a flimsy plastic cup. The implant, of the connections to the patient’s nerves, was removed after 30 days due to safety restrictions. He returned to using his previous prosthesis, but without the sense of feeling. The researchers project that it will be five years before some miniaturized version of the artificial hand will be available. The current device is bulky due to the size of the electronics.
Where does nano fit in to this work? What does our hands tell us? It is more than hard and soft. We are able to tell hot and cold. Without that capability, we could put on hand down on a cooking burner. There is a need for temperature sensing. We can tell sharp and dull. That capability is a function of the proximity of different sensors. The same can be said for wet and dry. The list of capabilities of the hand is long. The work that was reported, while significant, is only the start. If I consider the tip of a finger, how many sensors are required to determine temperature? How many to distinguish sharp from dull? How many to determine the differences between wet and dry or damp and dry? How small do the sensors need to be? Will they be significantly less than a micron?
Answering these questions leads to another. How do to multiplex all these signals to the brain? I think that we currently have the computing power to analyze the multiple signals coming from a finger or hand to determine conditions like hot or cold and only transmit the nerve impulse that indicates that condition. It will take some years before the optimal condition of signal processing is determined, but the controller(s) will be receiving a large number of inputs from very small areas. This will drive some of the connections into the nano realm. One can envision one or more microprocessors embedded in the hand (arm) that provides all the major signal processing and relays a much simpler set of signals to the brain.
Scientific advances, like this one, open up more opportunities to develop solutions that take advantage of materials in the nano realm.
References:
[1] http://www.thelocal.ch/20140205/epfl-helps-pioneer-feeling-bionic-hand
