US Patent #8,326,389 was issued today, with the title: “System for in vivo biosensing based on the optical response of electronic polymers” six years (to the week) after my adviser and I submitted our first application. The technology is based on the color change that the polymer polyaniline undergoes when it changes chemical states:
The half-oxidized form, emeraldine base (EB) is purple-blue, while the completely reduced form, leucoemeraldine base, is yellow. By entrapping an enzyme inside the polymer layer, the concentration of the target molecule can be detected by monitoring the color change of the polymer at specific wavelengths. The exciting part is that polyaniline is biocompatible, so a chip containing the polymer and enzyme might be implanted under the skin of a patient with diabetes, and a watch-type monitor worn on top of the implant site can probe the it with light through the skin and measure the color change based on the reflectence. The goal is reduce or eliminate the need for finger-prick testing of blood sugar for insulin-dependent diabetics. Further, we hope to one day be able to create a closed-loop system, in which real-time data from the monitor can be provided directly to an insulin pump, to realize a completely autonomous artificial pancreas.