A graphene-coated AFM probe for durable and reproducible nanoscale electronic measurements

Conductive atomic force microscopy (cAFM) is a powerful tool for investigating electronic and thermoelectric properties at the nanoscale. However, the widespread application of cAFM is hindered by the rapid wear and unpredictable failure of metal-coated probes, leading to poor measurement reproducibility and limited probe lifetime. Here, we report a scalable fabrication method for graphene-coated cAFM probes using the Langmuir-Blodgett technique. These probes exhibit exceptional mechanical durability, including resistance to both friction-induced wear and high-current stressing, and maintain stable electrical performance over extended use. When applied to self-assembled monolayers (SAMs), the graphene-coated probes yield narrow conductance distributions, significantly improved measurement reproducibility across different probe batches, and a substantial reduction in short-circuit artifacts. The graphene coating also provides a more compliant tip-sample contact, minimizing damage to soft molecular layers. Electronic transport and thermoelectric measurements further confirm the reliability of these probes, revealing tunnelling characteristics and Seebeck coefficients consistent with established values. Our work establishes a robust and scalable platform for nanoscale electrical characterisation, overcoming a critical limitation in conventional cAFM and opening avenues for long-term, reproducible studies in molecular electronics and beyond.