A miniature CuO nanoarray sensor for noninvasive detection of trace salivary glucose

An ultrasensitive mini-sensor has been developed for nonenzymatic and noninvasive determination of trace glucose in saliva. The miniature detector exhibits ultra-high sensitivity and resolution at very low glucose concentration owing to the excellent electrocatalytic activity and electron transfer rate of the prepared 3D ordered CuO nanoflake array in-situ grown on a copper foil. The structure and morphology of the cupric oxide nanoarray were characterized by X-ray powder diffraction and scanning electron microscopy. The electrocatalysis of the CuO nanoarray modified electrode to glucose was demonstrated by cyclic voltammetry and chronoamperometry. The modified electrode presents a high sensitivity of 4954 μA mM^-1 cm^-2 to glucose at + 0.55 V with a wide linear range of 1.0 μmol/L to 6000 μmol/L and a low detection limit of 0.1 μmol/L and long-term stability. Furthermore, the mini-sensor can clearly distinguish diabetics from healthy people because of its excellent sensing performance. The developed miniaturized sensor holds the prospect for noninvasive determination of trace glucose in saliva for diabetic patients.