Lift-Off Free Fabrication Approach for Periodic Structures with Tunable Nano Gaps for Interdigitated Electrode Arrays

Abstract

We report a simple, low-cost and lift-off free fabrication approach for periodic structures with adjustable nanometer gaps for interdigitated electrode arrays (IDAs). It combines an initial structure and two deposition process steps; first a dielectric layer is deposited, followed by a metal evaporation. The initial structure can be realized by lithography or any other structuring technique (e.g., nano imprint, hot embossing or injection molding). This method allows the fabrication of nanometer sized gaps and completely eliminates the need for a lift-off process. Different substrate materials like silicon, Pyrex or polymers can be used. The electrode gap is controlled primarily by sputter deposition of the initial structure, and thus, adjustable gaps in the nanometer range can be realized independently of the mask or stamp pattern. Electrochemical characterizations using redox cycling in ferrocenemethanol (FcMeOH) demonstrate signal amplification factors of more than 110 together with collection factors higher than 99%. Furthermore, the correlation between the gap width and the amplification factor was studied to obtain an electrochemical performance assessment of the nano gap electrodes. The results demonstrate an exponential relationship between amplification factor and gap width.

CRISPR/Cas13a‐Powered Electrochemical Microfluidic Biosensor for Nucleic Acid Amplification‐Free miRNA Diagnostics

“…Besides that, an additional electrochemical signal amplification via a so‐called redox cycling by using interdigitated electrode arrays (IDAs) can be combined with our microfluidic stop‐flow measurement protocol. In our previous published works, signal amplifications of more than 150 times are achieved, employing nanogap IDAs with 100 nm gap size . Combining this technique with our CRISPR‐based biosensor, the LOD of our system could be reduced to less than 100 f m .…”

“…In our previous published works, signal amplifications of more than 150 times are achieved, employing nanogap IDAs with 100 nm gap size. [55][56][57] Combining this technique with our CRISPRbased biosensor, the LOD of our system could be reduced to less than 100 fm.…”

Superplastic Formation of Metal Nanostructure Arrays with Ultrafine Gaps

“…Nanogaps between metallic nanostructures are of enormous importance in nanotechnology and have wide applications in nanolithography, field‐enhancement‐based plasmonic sensors, heat‐assisted magnetic recording, imaging, and trapping/manipulating of nanoscale particles and quantum dots . Electrodes with nanogaps could be used in electrical sensing devices and enable ultrafast or label‐free single‐molecule detection . Shrinking gap distances are found to exponentially increase the field enhancement and electrical current response, and thus promote device performances …”

“…Electrodes with nanogaps could be used in electrical sensing devices and enable ultrafast or label‐free single‐molecule detection . Shrinking gap distances are found to exponentially increase the field enhancement and electrical current response, and thus promote device performances …”

CRISPR/Cas13a powered electrochemical microfluidic biosensor for nucleic acid amplification-free miRNA diagnostics

“…Besides an optimization of the immobilization strategy, an additional electrochemical signal amplification via a so-called redox cycling by interdigitated electrode arrays (IDAs) can be combined with our microfluidic stop-flow measurement protocol. In our previous published works, signal amplifications of more than 150-times is achieved, employing nanogap IDAs with 100 nm gap size [56][57][58] . With a combination of this technique and our CRISPR based biosensor, the LOD of our system could be reduced to less than 100 fM.…”