Memristive Biosensors Under Varying Humidity Conditions

Abstract

We attempt to examine the potential of silicon nanowire memristors in the field of nanobiosensing. The memristive devices are crystalline Silicon (Si) Nanowires (NWs) with Nickel Silicide (NiSi) terminals. The nanowires are fabricated on a Silicon-on-Insulator (SOI) wafer by an Ebeam Lithography Technique (EBL) process that allows high resolution at the nanoscale. A Deep Reactive Ion Etching (DRIE) technique is used to define free-standing nanowires. The close alignment between Silicon (Si) and Nickel-Silicide (NiSi) terminals forms a Schottky-barrier at their junction. The memristive effect of the fabricated devices matches well with the memristor theory. An equivalent circuit reproducing the memristive effect in current-voltage (I-V) characteristics of our silicon nanowires is presented too. The memristive silicon nanowire devices are then functionalized with anti-human VEGF (Vascular Endothelial Growth Factor) antibody and I-V characteristics are examined for the nanowires prior to and after protein functionalization. The uptake of bio-molecules linked to the surface of the memristive NWs is confirmed by the increased voltage gap in the hysteresis curve. The effects of varying humidity conditions on the conductivity of bio-modified memristive silicon nanowires are deeply investigated.