Development of highly sensitive polysilicon nanogap with APTES/GOx based lab-on-chip biosensor to determine low levels of salivary glucose

A highly sensitive and non-invasive label-free biosensor was demonstrated for glucose detection using (3-aminopropyl)triethoxysilane (APTES) and glucose oxidase (GOx) surface modified polysilicon nanogap (PSNG) lab-on-chip. Fabricated gap size below 100 nm nanogap (NG) was used to discriminate the detection of the prepared dextrose monohydrate (DEX) which used as reference. The results were compared with salivary glucose (SAL) samples and an on spot blood glucometer. A simple immobilization step of APTES and GOx was demonstrated and the result shows an excellent catalytic activity toward the oxidation of glucose with a current sensitivity of 42.08 μA mM−1 cm−2 (or NG conductance sensitivity of 165.3 nS cm−1). It was found that the working capability of this enzyme based biosensor was extremely wide linear ranging from 5 μM to 50 mM, and the limit of detection (LOD) can be achieved down to 0.6 μM. Moreover, the amperometric response has affectively distinguished, the sensor response time of 3 s is achieved. The reproducibility and stability of the enzymatic activity of biosensor were successfully distinguished for glucose sensing. AC dielectric and impedance spectroscopy measurement also shows insignificant effect of polarization which is due to the accumulation of ions (double layers) on the surface of PSNG electrodes. Therefore, this glucose biosensor could be an attractive candidate for commercialization as a point-of-care clinical diagnostic tool.