Ultra-sensitive polysilicon wire glucose sensor using a 3-aminopropyltriethoxysilane and polydimethylsiloxane-treated hydrophobic fumed silica nanoparticle mixture as the sensing membrane

In this paper a highly sensitive glucose biosensor is proposed based on a polysilicon (poly-Si) wire structure coated with 3-aminopropyltriethoxysilane (gamma-APTES) mixed with polydimethylsiloxane-treated hydrophobic fumed silica nanoparticles (NPs) as the sensing membrane. The gamma-APTES and fumed silica NPs mixture was directly transferred to and coated onto the poly-Si wire region with the help of a focus-ion-beam (FIB) processed capillary atomic-force-microscope (C-AFM) tip. After the necessary curing and UV illumination processes, the resultant sensor showed an extremely wide linear detection range from 0.1 mu M to 10 mM with a channel current sensitivity as high as 5.33 AmM-1 cm(-2) (or a channel conductance sensitivity of 70 mu S mM(-1)), and a detection limit as low as 10 nM can be achieved. Our experimental results showed that the poly-Si wire sensor has good selective analysis and operational stability on glucose detection under a 10:1 concentration ratio of glucose and uric acid. Its linear range and lowest detection limit remain virtually unimpaired in the presence of uric acid. (C) 2009 Elsevier B. V. All rights reserved.