Parylene-based stretchable neural electrodes with serpentine interconnects

Abstract

Parylene C has rapidly gained popularity as a flexible and biocompatible material for next generation chronic probes. However, the mechanical strains attributed to the intracranial pressure and micromotion may compromise the longevity and biostability of implanted neural devices. To obtain conformable bioelectronic interfaces, it is essential to incorporate serpentine metal interconnects in flexible neural electrodes to achieve stretchability. In this paper, the influence of straight segments on the mechanical behavior of serpentine-shaped Parylene C probes has been investigated by finite element analysis. The etching performance of Parylene C with different masks are compared and the optimum masking material is the SiO2 film grown at a low temperature by inductively coupled plasma chemical vapor deposition (ICP-CVD). In vitro electrochemical measurements verify excellent electrode function with a low impedance of 13±0.4 kΩ at 1 kHz, which is beneficial for high-resolution neural recording.