Zinc-Air Batteries as Oxygen Soil Sensors

Oxygen in soil plays a critical role in facilitating plant physiological processes and regulating emissions of greenhouse gasses, like methane and nitrous oxide. Consequently, there is a growing need for high temporal and spatial resolution data on soil oxygen levels between 0% and 21%. However, traditional optical oxygen sensors rely on external power supplies, while conventional galvanic oxygen sensors use expensive precious metals, limiting their widespread deployment in soil. Here, we introduce a low-cost and scalable alternative by demonstrating stencil-printed zinc-air batteries as soil oxygen sensors. We explore hydrophilic and hydrophobic binders in carbon-based oxygen catalyst and zinc anode inks and develop a polypropylene packaging system to protect the sensors from fluctuations in soil moisture. We compare amperometric and potentiometric characterization of the devices as oxygen sensors and examine their sensitivity, stability, and lifetimes across temperatures between 12-30 °C and oxygen levels between 0-21%. This affordable oxygen sensing technique marks an important step towards the development of zinc-air batteries as alternative systems for measuring oxygen levels in soil, enabling the collection of high resolution environmental data.