Implantable wireless 64-channel system with flexible ECoG electrode and optogenetics probe

This paper presents a wireless 64-channel electrocorticogram (ECoG) recording system with 2-channel optogenetics manipulation. The proposed system, which is designed minimally to make it implantable into an animal, comprises a main board (75 mm × 40 mm × 12 mm and 33.53 g) and analog-to-digital converter (ADC) boards (25 mm × 20 mm × 2.5 mm and 0.98 g). Each ADC board has an 8-channel 24-bit ADC module that can be connected to the main board with a flexible cable. A biocompatible and flexible ECoG electrode is proposed for non-invasive monitoring. The electrode is covered by shape-memory polymer, which is solid at room temperature (27°C) and flexible at body temperature (35°C). The solid electrode be inserted into a brain. The electrode becomes flexible because of the brain temperature. In addition to the recording channels, two blue and yellow LEDs are developed on a flexible polyimide cable (50 μm thickness and 500 μm width) for optogenetics. This paper presents experimentally obtained results demonstrating that the proposed system records the ECoG of a rat with the flexible electrode and the proposed wireless system.