Monitoring and modeling of Quartz Crystal Microbalance sensors in a four-point probe configuration with a superconducting ammeter

The Quartz Crystal Microbalance is an extremely sensitive instrument for detecting surface and thin-film changes, with sensitivities in the nanogram regime. Primary characterization is often achieved by monitoring changes in the fundamental resonant frequency of the sensor, which limits the ability to model the data collected from multi-component systems. Recent advances have allowed for the frequency and dissipation of QCM sensors to be monitored at the fundamental frequency and higher overtones, dramatically increasing the utility of this instrument for complex systems. In this short communication, we wish to describe a proof-of-concept, four-point probe system for measuring absolute voltage drops and currents at 5 MHz, including a superconducting sensor serving as an ammeter, along with multiphysics simulations providing comparable results. This data allows for direct comparison to predictions from linear piezoelectric models.