Novel Printed Soil Decomposition Sensors Based on Biodegradation

The in situ sensing of soil health through the monitoring of microbial and enzymatic activity has remained a challenge, and is typically limited to laboratory techniques that are time and labor intensive. In addition, results from assessments done offsite do not always reflect real time bio-chemical-physical processes occurring in soil. Here, we present a novel printed decomposition sensor comprising a poly(hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and carbon composite material.¹ As the PHBV binder biodegrades in soil, the resistivity of the composite increases, which can be easily read with low-cost, wireless readout equipment. A correlation can be drawn between sensor response and general microbial activity in both soil and compost tea in as little as 14 days. Since PHBV is degraded by numerous microbes in the soil, it can be considered a “broad spectrum” decomposition sensor. However, this sensor is also a proof of concept that can possibly be modified to detect more specific soil decomposition activity, such as denitrification. We propose that selectivity can be achieved by mapping the enzyme(s) or microbe(s) of interest to a list of candidate binder materials that they reliably degrade. This design methodology considers the physical and chemical properties of these materials before and after degradation in soil and possible effects by interference enzymes and microbes.

1. Atreya, M.; Desousa, S.; Kauzya, J.; Williams, E.; Hayes, A.; Dikshit, K.; Nielson, J.; Palmgren, A.; Khorchidian, S.; Liu, S.; Gopalakrishnan, A.; Bihar, E.; Bruns, C. J.; Bardgett, R.; Quinton, J. N.; Davies, J.; Neff, J. C.; Whiting, G. L. A Transient Printed Soil Decomposition Sensor Based on a Biopolymer Composite Conductor. Adv. Sci. 2022, 2205785, 1–10. https://doi.org/10.1002/advs.202205785.