Bio-inspired 3D neural electrodes for the peripheral nerves stimulation using shape memory polymers

Peripheral nerves stimulation has been widely used in clinical practices, such as the vagus nerve stimulation (VNS) for heart failure, and motor nerve stimulation for controlling the prosthetics. However, the nerve injuries induced by the large mechanical and geometrical mismatch and complex surgical implantation process have restricted the further applications. Here, inspired by twining plants such as morning glories, we developed a 3D neural electrode that integrates the nano-gold film on flexible shape memory polymer (SMP) substrate from 2D planar state. Upon the response to 50°C normal saline, the flattened neural electrodes can self-climb to the 3D peripheral nerves with the aid of the shape memory effect. Two in vivo animal experiments are used to demonstrate the clinical practicality, i.e., VNS for the control of the heart rate (HR) and sciatic nerve stimulation for the control of the leg's movements. This technology offers a paradigm that fabricating the 3D bioelectronics in 2D planar state to match the 3D biological tissues by utilizing smart materials, and shows great potentials in clinical practices.