A long-term stable and flexible glucose sensor coated with poly(ethylene glycol)-modified polyurethane

Abstract Flexible biosensors have the great potential to be applied in medical diagnosis, wearable devices, fermentation and other fields. This paper proposes a manufacturing scheme of a flexible enzymatic glucose sensor coated with polyurethane modified by poly(ethylene glycol), PU-PEG, as a protective membrane, which can overcome the problems of poor consistency and short service life of the electrochemical sensor. A platinum-black electrode formed by electroplating platinum-black nanoparticles onto a flexible gold electrode is used as an enzyme carrier. The enzyme is electrosprayed evenly onto the electrode to avoid aggregation and to control quality. Glutaraldehyde is used as a cross-linking agent to immobilise the enzyme layer. Additionally, using PU-PEG as the protective membrane improves the anti-interference performance, controls the enzymatic reaction rate and makes long-term stable operation of the sensor possible. The experimental results show that the linear range of the sensor is 0.5 ~ 25 mM, the minimum detection limit is 0.25 mM, and the sensitivity is as high as 3.418 μA/mM. The measurement results of the sensors show good consistency, with a maximum absolute deviation of only 5.52%. The effective working time in 37℃ bovine serum with a glucose concentration of 5 mM is up to 23 days.