ZnO nanorod-based FET biosensor for continuous glucose monitoring

This paper reports a high-performance glucose biosensor using ZnO nanorod-based field effect transistor (FET) to continuously monitor glucose concentration. Sensing area reduction of the sensor for minimally-invasive glucose monitoring with high sensitivity and good stability is demonstrated. The biosensor is fabricated via a hydrothermal growth of semiconducting ZnO nanorods between source and drain micro-electrodes incorporating with alternating current (AC) electric-field control. ZnO nanorod structured FET acts as a frequency mixer to transduce glucose concentration into a current change at certain difference frequency, which is measured by a lock-in amplifier. Due to the large surface-to-volume ratio of ZnO nanorods and the advanced frequency mixing detection scheme, good anti-jamming capability and long-term stability are realized. The glucose sensor achieves a high sensitivity of 1.6   mA/(μM-cm 2 ), a glucose concentration detection limit of 1   μM, and excellent long-term stability shown in 38-h continuous monitoring. In contrast to the state-of-the-art glucose sensors, the developed biosensor exhibits competitive advantages in sensitivity, long-term stability, tiny size and fabrication cost, which indicates its promising application potential in wearable continuous glucose monitoring for diabetics.