Cellulose acetate-coated capacitive sensor for determining carbon-cycle enzymes activity and as a microbial Indicator for soil health

Abstract

This study demonstrates cellulose acetate (CA)-coated screen-printed carbon electrodes (SPCEs) for soil microbial activity detection. A capacitive sensor design utilizes a coated CA layer for effective insulation in electrolytes, eliminating the need for additional signal protection. Optimization involved comparing spin and dip coating methods, with a one-layer 10-second dip coating identified as the best balance between quality and yield. These CA/SPCEs exhibited remarkable stability over a month, suggesting their potential for long-term use in monitoring agricultural soils. Analysis of CA/SPCE profile and thickness provided insights into surface characteristics and the impact of the CA coating on electrode roughness. ATR-FTIR analysis, along with capacitive sensing, demonstrated superior sensitivity and precision for monitoring CA film degradation compared to mechanical gauges. Chemical degradation studies suggest CA's potential immunity in near-neutral environments, while enzymatic degradation investigations revealed dominance by enzymes, particularly in the initial stages. The CA/SPCE sensor responds to both enzymatic and chemical degradation, potentially serving as an indicator of total soil microbial activity. Soil experiments explored CA/SPCE with Cap-S for microbial activity sensing. Significant differences in the long-term degradation rate were observed in mycorrhizal fungi-enriched soil compared to controls, highlighting microbial influences. This study underscores the adaptability and versatility of this technology, particularly for assessing C-cycle microbial activity in agricultural fields.

Keywords: Capacitive sensor; Carbon-cycle enzymes; Cellulose acetate; Screen-printed carbon electrode; Soil.