Development of highly sensitive polysilicon nanogap withAPTES/GOx based lab-on-chip biosensor to determine low levelsof salivary glucose

tA 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 detec-tion of the prepared dextrose monohydrate (DEX) which used as reference. The results were comparedwith salivary glucose (SAL) samples and an on spot blood glucometer. A simple immobilization step ofAPTES and GOx was demonstrated and the result shows an excellent catalytic activity toward the oxi-dation of glucose with a current sensitivity of 42.08 A mM?1cm?2(or NG conductance sensitivity of165.3 nS cm?1). It was found that the working capability of this enzyme based biosensor was extremelywide linear ranging from 5 M to 50 mM, and the limit of detection (LOD) can be achieved down to0.6 M. Moreover, the amperometric response has affectively distinguished, the sensor response timeof 3 s is achieved. The reproducibility and stability of the enzymatic activity of biosensor were success-fully distinguished for glucose sensing. AC dielectric and impedance spectroscopy measurement alsoshows insignificant effect of polarization which is due to the accumulation of ions (double layers) onthe surface of PSNG electrodes. Therefore, this glucose biosensor could be an attractive candidate for commercialization as a point-of-care clinical diagnostic tool.