Spiking Chemical Sensor (SCS): A new platform for neuro-chemical sensing

A spiking chemical sensor (SCS) is presented for detection of neurogenic ion concentration associated with active nerve fibres in nerve bundles. Based on the "integrate-and-fire" circuit, the SCS uses a chemically-modified ISFET front end encoding the sense data in the spike domain. Used in an array, it provides a spatio-temporal map of chemical activity around the nerve bundle which may be relayed off chip using low power asynchronous communication hardware. The circuit is shown to be tunable to yield a linear relation with either pH or actual hydrogen ion concentration. Furthermore, its compact pixel footprint in addition to efficient use of the sensing surface, makes it ideal for use in neuro-chemical imaging.