This article addresses a novel fabrication process for an electrocorticogram (ECoG) electrode array. It consists of three regions: a flexible recording area, a flexible cable, and a rigid field for soldering the connectors. The flexible components can adapt to the curved shape of the cerebral cortex. Furthermore, the entire structure is a free-standing membrane, attached by removable polyimide straps to its carrier substrate. This configuration allows for a high level of control during soldering, electrode characterization and sterilization, as well as a soft release of the array off its carrier just before implantation. The array contains 128 gold electrodes, each 300 nm thick, sandwiched between two 5 μm thick polyimide films. The measuring area of the device is a regular hexagon with a side length of 7.2 mm, designed for implantation on the primary visual cortex of a Rhesus monkey. The flexible cable is 4 cm long. The rigid soldering area was designed for 4 × 32 OMNETICS connectors. The line resistance from an electrode site to the corresponding electrical connector pin is 540 Ω.

This paper presents a wireless system, designed for electrocortical (ECoG) neural recordings, consisting of an implantable flex-rigid ECoG array and a wireless electronic platform. The array is designed for implantation on top of the visual cortex of a Rhesus monkey. The electronic platform contains pre-amplifiers and multiplexer stages, analog-digital converters (ADCs), an in-house developed and reconfigurable ASIC, an RF data transceiver and an inductive energy link. Our ASIC provides user-defined selection of channels (≤128), adjustable channel resolution (1-16bit), sample rate (39S/s-10kS/s), and configurable analog filters. The functionality of the whole system is successfully demonstrated by an in vitro test.