Molecularly imprinted polymer amalgamation on narrow-gapped Archimedean-spiral interdigitated electrodes: resistance to electrolyte fouling in acidic medium

A conventional photolithography technique was used to fabricate three types of Archimedean-spiral interdigitated electrodes (AIDEs) containing concentric interlocking electrodes with different electrode and gap sizes, i.e., 150 μm (D1), 100 μm (D2), and 50 μm (D3). The precision of the fabrication was validated by surface topography using scanning electron microscopy, high power microscopy, 3D-nano profilometry, and atomic force microscopy. These AIDEs were fabricated with a tolerance of ± 6 nm in dimensions. The insignificant current variation at the pico-ampere range for all bare AIDEs further proved the reproducibility of the device. The large gap sized AIDE (D1) is insensitive to acidic medium, whereas D2 and D3 are insensitive to alkali medium. D2 was the best with regard to its electrical characterization. Furthermore, uniformly synthesized molecularly imprinted polymer (MIP) nanoparticles prepared with human blood clotting factor IX and its aptamer were in the size range 140 to 160 nm, attached on the sensing surface and characterized. The average thickness of deposited MIP film was 1.7 μm. EDX data shows the prominent peaks for silicon and aluminum substrates as 61.79 and 22.52%, respectively. The MIP nanoparticles-deposited sensor surface was characterized by applying it in electrolyte solutions, and smooth curves with the current flow were observed at pH lower than 8 and discriminated against alkali media. This study provides a new MIP amalgamated AIDE with nano-gapped fingers enabling analysis of other biomaterials due to its operation in an ideal buffer range.