Flexible lactate and glucose sensors using electrolyte-gated carbon nanotube field effect transistor for non-invasive real-time monitoring

We demonstrate flexible, low cost glucose and lactate sensors using novel enzyme immobilization scheme, primarily aimed toward wearable devices. The intrinsic chemical nature of polyimide films is harnessed to immobilize the enzyme on the polyimide substrate using a dicarboxylic acid. Sensors are fabricated using carbon nanotube as an active channel material. Minimum degradation of the transistor performance is seen after enzyme immobilization. The lowest concentration that can be resolved effectively is in pM range. The sensors demonstrate good sensing ability in the physiological range for wearable and implantable devices. The sensors were re-measured after three weeks and still retain their sensing ability with some decrease in the sensitivity. They also demonstrate good endurance against mechanical deformations.