Abstract
Precision horticulture demands affordable and versatile platforms to test a variety of sensors. However, current solutions are often costly, complex, and limited in scope, hindering widespread adoption. Here, we present a modular and practical sensor system designed for the integration and evaluation of printed impedimetric sensors. The platform includes an impedance analyzer, two 16-channel multiplexers, and a Raspberry Pi. Using the developed data acquisition system, we fully characterized the electrical impedance spectroscopy response of an ammonia gas sensor and three humidity sensors over a frequency range from 500 Hz to 10 MHz. The chemiresistive ammonia sensor, tested in a controlled laboratory environment using a gas exposure setup, showed optimal operation at 4 kHz, demonstrating high sensitivity in impedance magnitude measurements. In contrast, the paper-based humidity sensors were evaluated directly on plants under field conditions, where analysis of phase angle (Θ) and impedance magnitude (Ω) identified optimal measurement points. At lower frequencies (below 104 Hz), both parameters showed strong correlations with relative humidity, with correlation coefficients of 0.52±0.03 and −0.54±0.02, respectively. These results indicate a capacitive response to moisture absorption and good reproducibility between devices. Beyond 105 Hz, the correlation weakened, indicating a transition in sensor response mechanisms. Our results demonstrate the effectiveness of the platform in both laboratory and field environments, providing a robust and cost-effective tool to evaluate impedimetric sensors. By enabling rapid and accurate assessments, this system advances agricultural technology for more efficient, sustainable precision horticulture.