Preliminary results on the design of a tool for inserting of transverse intrafascicular multichannel electrodes (TIME) into the peripheral nervous system

Transverse intrafascicular multichannel electrodes (TIMEs) are polyimide-based microelectrodes, which are potentially very interesting to restore sensorimotor functions in disabled people. By means of microstimulation of the nerve stump of an amputee, it can be possible to manipulate the phantom limb sensation, to provide sensory feedback to upper limb amputees, and to investigate methods of treatment of phantom limb pain. The current insertion procedure of TIMEs is completely done by hand. This makes the task difficult. This paper presents the preliminary results related to the development of a robotic tool to increase the accuracy in electrode placement and reduced size of the working area. The possibility to manage insertion parameters such as force, velocity, and positioning, could decrease the risk of damaging the nervous tissue, improving the coordination, and making placements repeatable. With the aim of solving the issues above, we developed a first prototype of a 4DoF multi-axis device. Additional strategies concerning system components and control are discussed. We performed characterization of implantation mechanics to derive mechanical design specifications for the robotic device. Force characterization of the pig peripheral nerve during penetration of the needle at three velocities (1, 30, 40 mm/sec) was executed. Results shown inverse relationship between maximal force and velocities values. The force values extracted varied between 0.081-0.174 N.