Continuous glucose monitoring using a microneedle array sensor coupled with a wireless signal transmitter

A minimally invasive wireless biosensor was developed for glucose monitoring using human blood. The sensor probe was shaped in a microneedle array with a cyclic olefin copolymer. FAD-glucose oxidase (GOx) was covalently bound to a terthiophene carboxylic acid (TCA) monomer followed by electropolymerization on a gold-coated microneedle (AuMN) array using the potential cycling method (AuMN/pTCA-GOx). The formation of the sensing probe layer on the needle was confirmed by employing electrochemical and surface characterization experiments. To prevent the interfering species and the detaching of the probe material, the AuMN/pTCA-GOx surface was protected with Nafion. To enhance the repeatability and stability of the sensor, it was pretreated by applying the sequential negative and positive pulses immediately prior to each measurement. The sequential pulse allowed the sensor to have a high repeatability (Coefficient of variation = 1.1%, n = 10), and continuously long-term stability (Coefficient of variation = 5.56% for 72 h). The sensor has an excellent linear response at glucose concentrations between 0.05 and 20.0 mM (R-2 = 0.99) with a sensitivity of 0.22 mu A/mM(-1) cm(-2) (Coefficient of variation = 1.7%) and the detection limit of 19.4 ( +/- 0.62) mu A. The reliability of the proposed method was performed on finger through coupling of the sensor part to a reusable wireless transmitter that sends the measured values to a mobile phone via Bluetooth.