Powering a molecular delivery system by harvesting energy from the leaf motion in wind

Abstract

Smart agriculture tools as well as advanced studies on agrochemicals and plant biostimulants aim to improve crop productivity and more efficient use of resources without sacrificing sustainability. Recently, multiple advanced sensors for agricultural applications have been developed, however much less advancement is reported in the field of precise delivery of agriculture chemicals. The organic electronic ion pump (OEIP) enables electrophoretically-controlled delivery of ionic molecules in the plant tissue, however it needs external power-supplies complicating its application in the field. Here, we demonstrate that an OEIP can be powered by wind-driven leaf motion through contact electrification between a natural leaf and an artificial leaf. This plant-hybrid triboelectric nanogenerator (TENG) directly charges the OEIP, enabling proton delivery into a pH indicator solution, which triggers visible color changes as a proof-of-concept. The successful delivery of up to 44 nmol of protons was revealed by pH measurements after 17 h autonomous operation in air flow moving the plant and artificial leaves. Several control tests indicated that the proton delivery was powered uniquely by the charges generated during leaf fluttering. The OEIP-TENG combination opens the potential for targeted and self-powered long-term delivery of relevant chemicals in plants, with the possibility of enhancing growth and resistance to abiotic stressors.