A fully handwritten-on-paper copper nanoparticle ink-based electroanalytical sweat glucose biosensor fabricated using dual-step pencil and pen approach

This article reports a facile fabrication of a highly sensitive enzyme-free sweat glucose sensor over Whatman filter paper substrate employing a dual-step pencil and pen approach. Initially, two pencil-drawn electrodes (PDEs) are obtained on the filter paper through the manual abrasion of an 8B graphite pencil. Then, the sensing layer is drawn over one of the PDEs using a custom-made copper (Cu) nanoparticle ink (CuNP-ink) pen to form copper nanoparticle ink decorated PDE (CuNP-ink/PDE) which serves as a working electrode, while the other PDE is drawn with silver conductive ink (Ag-ink) pen to form reference electrode. The developed CuNP-ink/PDE is composed of 43.5% of metallic Cu nanoparticles, inducing a highly crystalline and conductive nature, thus promoting fast electron transfer during glucose electrooxidation. The developed sensor offers a sensitivity of 2691.7 mu AmM(-1)cm(-2), a detection limit of 0.5 mu M, a linear range of 1.2-40 mu M, and a fast response time of similar to 1.5 s. Besides, the sensor measurements are stable, reproducible, and selective in glucose sensing. Also, the reliability of the sensor is tested by comparing its performance with a UV-Visible spectrophotometer for proving its efficacy in sweat glucose detection. Experimental results evince the effectiveness of the designed sensor for glucose detection in human sweat.

Automated summary

This article presents a facile method for fabricating a highly sensitive enzyme-free sweat glucose sensor using pencil and pen approaches. The sensor demonstrates high sensitivity, fast response time, stability, and selectivity in glucose sensing.