Biohybrid generators based on living plants and artificial leaves: influence of leaf motion and real wind outdoor energy harvesting

Abstract

Plants translate wind energy into leaf fluttering and branch motion by reversible tissue deformation. Simultaneously, the outermost structure of the plant, i.e. the dielectric cuticula, and the inner ion-conductive tissue can be used to convert mechanical vibration energy, such as that produced during fluttering in the wind, into electricity by surface contact electrification and electrostatic induction. Constraining a tailored artificial leaf to a plant leaf can enhance oscillations and transient mechanical contacts and thereby increase the electricity outcome. We have studied the effects of wind-induced mechanical interactions between the leaf of a plant (Rhododendron) and a flexible silicone elastomer-based artificial leaf fixed at the petiole on power output and whether performance can be further tuned by altering the vibrational behavior of the artificial leaf. The latter is achieved by modifying a concentrated mass at the tip of the artificial leaf and observing plant-generated current and voltage signals under air flow. In this configuration, the plant-hybrid wind-energy converters can directly power light-emitting diodes and a temperature sensor. Detailed output analysis has revealed that, under all conditions, an increase in wind speed leads to nearly linearly increased voltages and currents. Accordingly, the cumulative sum energy reaches its highest values at the highest wind speed and resulting oscillations of the plant-artificial leaf system. The mass at the tip can, in most cases, be used to increase the voltage amplitude and frequency. Nevertheless, this behavior was found to depend on the individual configuration of the system, such as the leaf morphology. Analysis of these factors under controlled conditions is crucial for optimizing systems meant to operate in unstructured outdoor scenarios. We have established, in a first approach, that the artificial leaf-plant hybrid generator is capable of autonomously generating electricity outdoors under real outdoor wind conditions, even at a low average wind speed of only 1.9 m s−1.

Multisource energy conversion in plants with soft epicuticular coatings

“…Thus, also without rectifying the single signals such as by installing a diode bridge at each leaf (which was done in our previous prototypes 5,23 ), here, energy harvesting with positive power balance was possible. The model in Fig.…”

“…Advances in the understanding of material properties, biochemical mechanisms, and physical processes in artificial and biological matter have shown that living organisms and especially living plants can be exploited for energy conversion [1][2][3][4][5][6] and environmental sensing [7][8][9][10][11][12][13][14] by interfacing and modifying the plants with engineered materials and electronics that enable to turn them into ''devices''. [15][16][17][18] Plant-integrated solutions like light-emitting plants, 19 planthybrid sensing platforms, [7][8][9][10][11][12][13][14] plant-internal electronic circuits, 20,21 and plant-hybrid robotics, 22 as well as living plantdriven energy harvesting 1-3 using wind, 5,23 rain drops, 4 the root/ soil microbiome, [24][25][26][27] sap components, [28][29][30] temperature gradients, 31 and potential differences between soil and plant 32 endow great prospects for connecting plants to man-made technology and for sustainable concepts to derive novel energyautonomous devices, for example for environmental monitoring, in agriculture, climate change surveillan...…”

“…Plant-integrated solutions like light-emitting plants, 19 plant-hybrid sensing platforms, 7–14 plant-internal electronic circuits, 20,21 and plant-hybrid robotics, 22 as well as living plant-driven energy harvesting 1–3 using wind, 5,23 rain drops, 4 the root/soil microbiome, 24–27 sap components, 28–30 temperature gradients, 31 and potential differences between soil and plant 32 endow great prospects for connecting plants to man-made technology and for sustainable concepts to derive novel energy-autonomous devices, for example for environmental monitoring, in agriculture, climate change surveillance, ecosystem investigations etc. Table S1 (ESI†) gives an extended overview of approaches and principles of energy harvesting and sensing by plants and compares the output power of such devices.…”

Wind dynamics and leaf motion: Approaching the design of high-tech devices for energy harvesting for operation on plant leaves

“…Such devices are either permanently or transiently fixed on a plant leaf where they perform a specific task and have a potential impact on monitoring and preserving plants and ecosystems. Examples are sensors that measure plant parameters ( Khan et al., 2018 ; Jiang et al., 2020 ; Diacci et al., 2021 ; Fiorello et al., 2021 ; Dufil et al., 2022 ); molecule delivery platforms ( Fiorello et al., 2021 ); robots and drones that could use a plant or a leaf as support ( Graule et al., 2016 ; Fiorello et al., 2021 ; Jiaming et al., 2021 ), and, moreover, energy harvesting artificial leaves ( Jie et al., 2018 ; Meder et al., 2018 ; Meder et al., 2020a ; Wu et al., 2020 ; Meder et al., 2021 ; Meder et al., 2022 ).…”

“…The latter have recently been shown to be capable of converting wind into electrical energy: the artificial leaves installed on plant leaves exploit the wind-induced leaf oscillations and fluttering for a mechanical-to-electrical energy conversion ( Meder et al., 2020a ; Meder et al., 2021 ). In more detail, the motion of the artificial leaf fixed firmly on the petiole of the natural leaf causes the two surfaces to contact and separate due to air flow.…”