A Novel, Low Cost and Versatile Fabrication Method of Flexible Multi-electrode Array for Spinal Cord Stimulation

In this paper, a novel, low-cost multi-electrode array fabrication method has been proposed for epidural spinal cord stimulation (ESCS) to restore motion ability after paralysis due to spinal cord injury (SCI). In this approach, unlike the existing neural prosthesis technologies, costly standard microfabrication processes are eliminated. This makes the proposed electrodes cost-effective and suitable for massive production for clinical applications. Based on the conformability and mechanical compliance of the electrodes and spinal cord tissue, full polydimethylsiloxane (PDMS)-based passive multi-electrode array structure is proposed. The suggested neural electrode array structure consists of PDMS (as substrate) and embedded 100 μm-thick Cu wires (as conductive parts). Despite the fabrication and implementation challenges caused by the low Young modulus of PDMS, its suitable mechanical properties close to those of the spinal cord tissues make PDMS one of the best options. These electrodes were used along with pulse generator circuits providing biphasic pulse waveforms for two channels. Employing the ESCS system caused movement in the paralyzed limbs in an adult male Wistar rat. Our preliminary ESCS studies have shown that such electrode arrays are capable of neuronal stimulation effectively.