Assorted micro-scale interdigitated aluminium electrode fabrication for insensitive electrolyte evaluation: zeolite nanoparticle-mediated micro- to nano-scaled electrodes

Abstract

Biosensor with insensitive electrolyte variation is one of the basic norms to be investigated for developing a high-performance disease diagnostic with a non-biofouling. On the other hand, the optimum dimension of biosensor plays a significant factor to be considered for generating a biosensensing system with a least influence by the buffering agents. In this research, interdigitated aluminium electrode (AlIDE) with four different microscale gap sizes, 400, 100, 60 and 45 µm were fabricated through a photolithography technique on the silicon substrate. The accuracy of the device fabrication was justified by the morphological examination using field emission scanning electron microscopy, high-power microscopy and 3D-nano profilometer. The current amplified by four devices under bare condition was 2.55E−3 A at 2 V explains the accuracy of the device fabrication and the uniformity in the electric flow. Electrolyte scouting was executed on the fabricated AlIDEs with the pH ranges between 1 and 12, the results interpret small gap sized AlIDEs (60 and 45 µm) show the variation in the current with different pH solutions due to the ionic flux. The insensitivity of zeolite nanoparticle (~ 10 nm size) attached AlIDE with 400 µm and 100 µm at different pH solutions were analyzed. Linear current curves with least variations were attained from pH 1 to 11. At 2 V voltage supply, the amount of current generated by AlIDE with and without zeolite attachment during pH scouting were same (1E−4 A), with the same microscale gap sizes. However, there was no current fluctuation observed with zeolite attached AlIDE during pH scouting analysis. Further, the chemically functionalized zeolite nanoparticle behaves better than unmodified one and gold nanoparticle with the similar modifications. The results obtained in the present research denotes that microscale gap size was altered to nanoscale gap size in the presence of nanomaterials on the AlIDE sensing surface, enhances the sensitivity of the device and improves the insensitivity of device to the electrolytes. Thus, optimum microscale gap sized AlIDE is easier to fabricate, could be utilized for medical diagnostics with insensitive pH variation through the advanced physiochemical properties of nanomaterials.