Development of a Polydimethylsiloxane‐Based Electrode Array for Electrocorticography

Neural interfaces play an essential role to disclose neural networks and to assist paralyzed patients in past decades. As the conformability and longevity become vital issues for neural interfaces, flexible materials are increasingly engaged in the development of such devices. However, the development of devices comprised of polydimethylsiloxane (PDMS) is bothered because of its incompatibility with silicon microfabrication technology, mainly caused by different thermal expansion coefficients between metals and PDMS. Here, a PDMS‐based electrode array is developed through a single‐wafer processing by employing an intermediate parylene‐C layer, which allows stable and simple fabrication as well as easy miniaturization and integration with other components. The developed electrode array can detect visual evoked potentials (VEPs) through in vivo experiments using mice. The conformal contact and high spatial resolution are achieved by detecting distinctive VEPs from all 16 channels. To investigate the effect of electrode sizes on signal quality, three different diameters ranging from 20 to 120 µm are used, resulting in no clear correlation between the electrode size and signal quality. The developed device suggests the potential of PDMS‐based bioelectronics in various applications where the flexibility and conformability as well as the robustness of the device are all desired. A polydimethylsiloxane (PDMS)‐based microelectrode array for electrocorticography is reported in this study. Employing a thin intermediate parylene‐C layer between PDMS and metals enables the miniaturization in feature size and easy integration with hard components through a single‐wafer processing. The fabricated device can effectively detect in vivo visual evoked potentials, with high conformability, spatial resolution, and signal quality.