New Insights into the I/V hysteretic characteristics of Memristive Biosensors

Over the past decade, significant advancements have been made in the study of silicon nanowires (SiNWs). These nano-scaled devices can exhibit a memristive type of hysteresis in the current/voltage (I/V) plane that has been utilized in the biosensors leading to exceptional sensitivities up to the femto levels. Here we investigate the memristive properties of SiNW-based biosensors in their unmodified state, as well as after surface biofunctionalization with aptamers. The development of SiNWs involved a top-down nanofabrication approach, resulting in nanowires with $100\ nm$ -wide and $1 \ \mu m$ -long. Later, biofunctionalization was performed through controlled drop-casting. The experimental findings obtained in this study demonstrate for the first time that different SiNWs from the same fabrication batch can exhibit diverse memristive switching phenomena in the I/V plane. These phenomena encompass both volatile non-crossing memristive behavior as well as non-volatile crossing memristive responses. Furthermore, we demonstrate that the I/V hysteresis exhibited by bio-functionalized nanowires is determined by their inherent memristive characteristics and the induced capacitive effect. Drawing upon these new findings, a simple mathematical simulation model of the Memristive biosensor is developed and evaluated in SPICE.