Bionic hand that can feel Hip Kõiv Tallinn University of Technology 2014

Bionic hand Thinking of moving the arm, the prostethic arm will move Targeted muscle reinnervation (TMR) Amputated nerves are redirected to another muscle Biosensors, mechanical sensors, controller, actuator Neural interfacings

i-Limb Ultra bebionic3

Feedback system for a new kind of prosthesis Feedback system was connected to the amputee’s arm nerves. Implanted into the median and ulnar nerves of an amputee’s residuum. Motor commands were decoded by processing sEMG signals (superficial electromyogram).

Transversal intrafascicular multichannel electrodes (TIMEs) are used for closing the user-prosthesis loop and to trigger sensory feedback. Arm was able to modulate force during grasping and to identify physical characteristics of objects (palmar grasp, ulnar grasp, hand opening, and rest).

A - Blindfolded and acoustically isolated patient B – Median nerve C – Ulnar nerve

Peripheral nerve stimulation Feedback was restored by delivering electrical current through one TIME electrode. Maximum charge injected into both nerves was 8 and 24nC – much lower than theoretically injectable using TIME electrodes (120nC).

Results Patient could produce 3 levels of stable and discrete pressure with index and the little finger. Success rate of >90% in last sessions. Patient was able to control how forcefully he grasped objects, and feel their shape and stiffness. He could tell the differences among hard, medium and soft objects, and identify the shapes of specific objects such as a cylindrical bottle or round baseball.

A key problem is how electricity from the electrodes can inflame cells, forcing the body to grow tissue around the electrodes that dampen signals to and from the bionic hand. Scientists hope to further improve sensory feedback and overall control of bionics.

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