Ultra-low noise nanoporous Ag/AgCl electric field sensor for telluric electric field detection

This paper presents an ultra-low noise nanoporous Ag/AgCl electric field sensor fabricated using a sol in situ composite method, aiming to address the issues of high noise and significant drift encountered in traditional electric field sensors during low-frequency signal measurements. By utilizing polyvinylpyrrolidone (PVP) sol to regulate the nucleation process of AgCl and combining it with nano-silver powder, nanoscale Ag/AgCl particles were prepared. Through the use of NaCl as a pore-forming agent, an electrode with a porous structure was developed. A double-layer porous semi-permeable membrane encapsulation structure is employed, which protects the electrode from external environmental damage without compromising its performance, thereby improving its stability and lifespan. Experimental results demonstrate that the electrode exhibits a low source resistance of 0.13 Ω, the 24-h drift of less than 12 μV, and the self-noise of 0.874 nV/√Hz@1 Hz, with the working frequency band ranging from 0.1 Hz to 100 kHz, showcasing excellent frequency response and stability. Field tests in electrical prospecting further validated the electrode's high accuracy and reliability in measuring apparent resistivity, apparent polarizability, and spontaneous potential. This technological breakthrough provides robust technical support for deep resource exploration and long-term geoelectric field monitoring.