A cost effective and highly sensitive glucose biosensor based on a 3D silicon nano wire array electrode

In this study, a novel glucose biosensor based on a 3D silicon nanowire array (SNA) electrode was proposed. Metal-assisted etching (MAE) method using an AgNO₃ and HF mixing solution as the etchant is employed for fast etching of a silicon wafer to form the SNA electrode. A thin gold shell is then coated onto each silicon nanowire by sputtering. Potassium ferricyanide, glucose oxidase, and a Nafion thin film were then sequentially coated onto the fabricated 3D SNA for glucose detection. The effective sensing area of the fabricated 3D SNA electrode was measured to be 11.35 folds that of the corresponding plane electrode by steady-state voltammetry. Actual glucose detections illustrated that the SNA based devices could function at a sensitivity of 1,034 μA mM^-1 cm^-2 with a linear detection range from 55.1 μM-11.0 mM and detection limit of 11 μM. A fast response time of 2 s was also demonstrated. The proposed 3D SNA based glucose biosensing scheme possesses advantages of low cost, high sensitivity, and fast response.