Negative current response of non–enzymatic glucose sensor based on pure PEDOT: PSS conductive polymer

A simple non - enzymatic glucose sensor was successfully fabricated from a conductive polymer namely PEDOT: PSS with a facile drop coating on a screen-printed carbon electrode (SPCE). The amperometric technique was used in monitoring the current response of the glucose sensor in the NaOH and PBS solutions. A notable and distinct observation emerged, wherein the negative current response was observed as the glucose concentration was increased. The negative current response can be attributed to a unique mechanism of the glucose sensor namely the selective adsorption of glucose molecules. The current responses with various glucose concentrations in the NaOH and PBS solutions were identified as power laws with the equations of I (µA) = 56.519 C^−0.331 (mM) and I (µA) = 50.724 C^−0.029, respectively. The sensitivity values are 672 mM⁻¹ cm⁻² and 21 mM⁻¹ cm⁻² in NaOH and PBS, respectively. The limit of detection (LOD) was determined to be 0.5 mM for NaOH and 0.01 mM for PBS; the glucose sensor demonstrated superior sensitivity in NaOH because of the electrolyte strength. The numerous advantages of the present non-enzymatic glucose sensor modified with PEDOT: PSS on SPCE are the ease of fabrication, low cost, rapid monitoring, precise measurement, high sensitivity and selectivity, good reproducibility, and with long-term stability. The fabricated glucose sensor is suitable as a portable sensor for diabetes patients without utilizing elaborate and expensive laboratory protocols.