Printed Biodegradable Batteries for Soil Sensing Using a Fruit-Waste Based Separator

In 2019, the United States spent $357.8 billion on farm production where soil input (water, fertilizers, chemicals, etc.) accounted for the largest share at 27.1% of the total expenditure [1]. A significant cost reduction can be achieved by addressing inefficiencies in resource distribution caused by spatial variability in soil composition in a field. Precision Agriculture (PA) technologies implemented since the early 1990s have enabled tailored soil and crop management in heterogenous fields [2]. However, current state-of-the-art sensors are typically expensive and labor-intensive to install/uninstall, thereby restricting the high-density deployment required for high spatial resolution measurements.<br/>Our group has previously developed printed biodegradable capacitive soil moisture sensors using Zinc electrodes [3]. These sensors degrade in the soil into benign end products. While these sensors function without power, their data cannot be retrieved continuously without an integrated power source. There is a growing need to fabricate biodegradable power units that satisfy ultralow-power sensing devices and maintain robust functions. To address this, we have developed a transient energy storage system in the form of a fully biodegradable and biocompatible fruit-based battery with printed zinc and graphite electrodes that utilizes fruit waste as the electrolyte and separator. The system can function as a reserve battery and powers miniaturized wireless communication devices that require ultra-low power in the microwatt range. Here, we demonstrate the potential of the biodegradable fruit-based battery as a sustainable integrated power source in an agricultural field.<br/>[1] Farm Production Expenditures 2019 Summary. Agriculture, U.S.D.o.E., 2020<br/>[2] Swinton, S. M.; Lowenberg-DeBoer, J. Evaluating the Profitability of Site-Specific Farming. <i>Journal of Production Agriculture 1998</i>, 11 (4), 439−446<br/>[3] Yongkun Sui, Madhur Atreya, Subash Dahal, Anupam Gopalakrishnan, Rajiv Khosla, and Gregory L. Whiting, ACS Sustainable Chemistry & Engineering <b>2021</b> <i>9</i> (6), 2486-2495