Towards an implantable ultra-low power biochemical signal processor for blood and tissue monitoring

On-line, real time, physiological monitoring of blood and tissue requires ultra-low power biosensor technology. In this paper, we present the first reported results of the use of an ion sensitive field effect transistor (ISFET), operating in sub-threshold (weak inversion) to achieve nano-power biosensor performance. Measured data from a pilot study on blood samples using ISFET-based sensors biased in their weak inversion regions to measure ion and metabolite concentration is presented. Building blocks for the creation of low-power biochemical sensors with local processing are proposed. These include current-mode processing blocks such as translinear circuits as well as a form of "biochemical" logic. This paper demonstrates an important and necessary step towards biochemical VLSI.