Neural processes under-lying vision could be better understood with the help of a Brain Computer Interface (BCI) that could acquire and process the activity of a large number of visual area cells in real time.
A fully implantable cortical data acquisition system (CDAS) achieving high quality multichannel recording is needed to acquire signals from cortical cells. The proposed system architecture uses new circuits techniques to meet tight power consumption constraints, small area, and low noise requirements of neural amplification. The implantable microsystem includes: a microelectrode array connected to the circuits using flip-chip technology; an analog front-end per channel to limit noise and DC offset; a wavelet transform signal processor to compress and improve precision of extracellular signals detection; An analog to digital converter. The action potentials recorded from the visual area’s neurons are transmitted outside the body using an inductive telemetry link to a computer for data analysis.
Reported preliminary results demonstrate the ability to build an acquisition channel with a power budget of few dozens of microwatts and minimal input referred noise.
The front-end and the wavelet processor have been implemented in a 0.18 um CMOS process. Further research work includes in-vivo testing of the prototypes and experimental data analysis.
