Protein-Electrode Coupling Can Dominates Efficiency Without Affecting the Mechanism of Electronic Transport – Results From a Cross-Lab Comparative Study of Solid State Protein Junctions
69 Pages Posted: 12 Feb 2020
Date Written: December 27, 2019
Successful integration of proteins in solid-state electronics requires contacting them in a non-invasive fashion, with a solid conducting surface for immobilization as one such contact. The contacts can affect and even dominate the measured electronic transport. Often substrates, substrate treatments, protein immobilization, and device geometries, differ between laboratories. Thus, the question arises in how far results from different laboratories and platforms are comparable. We report and evaluate electronic transport measurements, planned for such comparison between different laboratories, using several schemes to contact a set of three proteins of largely different types. While for the same protein, measured with similar device geometry, results compare reasonably well, there are significant differences in current densities (an intensive variable) between different device geometries. Likely, these originate in the critical contact-protein coupling (~contact resistance), in addition to the actual number of proteins involved, because the effective junction contact area depends on the nanometric roughness of the electrodes and at times, even the proteins may increase this roughness. On the positive side our result show that understanding what controls the coupling can make the coupling a design knob. In terms of extensive variable, such as temperature, our comparison unanimously shows the transport to be independent of temperature. Our study places coupling and lack of temperature activation as key aspects to be considered in both modeling and practice of protein electronic transport experiments.
Keywords: Bioelectronics, electron transport, molecular contact, molecular electronic device
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