Soft Probe Electrical Contact: Eliminating Electrode Deposition and Enabling Reliable Measurements of Emerging Materials.

Electrical measurements of emerging materials such as thin films, two-dimensional materials, and fragile porous systems are often hindered by damage and contamination caused by conventional contact methods, including metal electrode deposition. In this study, we demonstrate the novelty and advantages of a mechanically compliant "soft probe" over conventional methods and conductive AFM. The non-destructive soft probe achieves stable electrical contact in the repulsive-force regime using a hairpin-shaped spring structure, allowing consistent measurements without active force control nor electrode fabrication. Case studies demonstrate that the soft probe prevents metal penetration and preserves intrinsic properties, as demonstrated in NiO resistive switching devices, and improves interface quality compared to deposited electrodes in ferroelectric measurements. It also enables electrical characterization of fragile materials such as metal-organic frameworks without inducing structural degradation. Furthermore, its mechanical compliance ensures stable operation under vibration and thermal stress, enabling measurements in vacuum and low-temperature environments. These results indicate that the soft probe provides a simple, versatile, and contamination-free platform for reliable electrical measurements, and represents a promising approach for the characterization of a wide range of emerging material systems.