“Paper and Inks”: Sustainable Sensing Through Development of Paper Platforms

The platform of biosensor plays a pivotal role in the efficacy of detection; therefore, the selection of an optimal material that meets all requisite criteria is essential. Paper as a platform for sensing application exhibit additive attributes over the other commercially available substrates as it might fulfils the ‘REASSURED’ benchmark introduced under WHO guidelines. The study entails the fabrication of an electrochemical biosensing platform using regular office paper with different GSM thickness (75, 85,120 and 140 GSM). The conductive inks, paper thickness, design pattern, hydrophobic layer and connection materials were iterated and optimized through multiple scans of cyclic voltammetry. A simplified design of three electrode system having reference and working electrode at an optimized distance of around 1mm, resulted in reduced ohmic resistance. The concentration and number of layers of conductive inks were optimized through conductivity measurements which lie between 1Ω to 4 Ω for reference electrode and 0.0005 MΩ to 0.025 MΩ for counter electrode. Working electrode was fabricated using two differently modified conductive CNTs ink where conductivity varied for PCNT as 0.06 kΩ to 0.1 kΩ while LCNT varied 0.014 kΩ to 1.33 KΩ. Beside this an ecofriendly volatile organic compound free hydrophobic reagents were also tested for fabricating the sensing region. The CV scans show stability of adsorbed conducting materials on the fabricated paper platform stating that the platform could be further evaluated for biosensing application.