Multisource energy conversion modes in minimally altered plants with soft epicuticular coatings

Living plants have recently been exploited for unusual tasks such as energy conversion1–6 and environmental sensing.7–12 Yet, using plants as small-scale autonomous energy sources1–5 was obstructed by insufficient power outputs for steadily driving even low-power electronics. Moreover, multicable and -electrode installations on the plants made a realization challenging. Here, we show that plants, by a minimal modification of the leaf epicuticular region and by exploiting their intrinsic circuitry, can be transformed into cable-free, fully plant-enabled integrated systems for multisource energy conversion. In detail, leaf contact electrification caused by wind-induced inter-leaf tangency was magnified by a transparent elastomeric coating on one of two interacting leaves for converting wind energy into harvestable electricity. Further, augmentation of the power output is achieved by coupling multi-frequency band radio frequency (RF) energy conversion modes using the same plant as an unmatched Marconi-antenna. In combination, we observed up to 1100 % enhanced energy accumulation respective to single source harvesting and a single plant like ivy could power a commercial sensing platform wirelessly transmitting environmental data. This shows that living plants could autonomously supply application-oriented electronics while maintaining the positive environmental impact13 by their intrinsic benefits such as O2 production, CO2 fixation, self-repair, and many more extremely difficult (if at all possible) to realize in artificial harvesters.

Ultra-wide band energy harvesting for ultra-low power electronics applications

In this work, the feasibility of energy harvesting in the useful UWB band (i.e., 3.1-10.6 GHz) is analytically investigated. A typical UWB communications/EH chain in this band is modeled and analyzed, considering the spectral constraints imposed by the federal communications commission (FCC) to UWB signaling. Based on the developed model, accurate analytical expressions are derived for the average received powers of two common types of impulse radio UWB (IR-UWB) signaling waveforms. Numerical simulations on the system-level show excellent agreement with the obtained analytical expressions. Moreover, the DC power levels expected from spectrally constrained IR-UWB waveforms are extremely low (less than 0.3 microwatt) and, accordingly, provide useful guidelines for the design and development of ULP electronics applications in the sub-microwatt range.

Contact-electrification-activated artificial afferents at femtojoule energy

Low power electronics endowed with artificial intelligence and biological afferent characters are beneficial to neuromorphic sensory network. Highly distributed synaptic sensory neurons are more readily driven by portable, distributed, and ubiquitous power sources. Here, we report a contact-electrification-activated artificial afferent at femtojoule energy. Upon the contact-electrification effect, the induced triboelectric signals activate the ion-gel-gated MoS2 postsynaptic transistor, endowing the artificial afferent with the adaptive capacity to carry out spatiotemporal recognition/sensation on external stimuli (e.g., displacements, pressures and touch patterns). The decay time of the synaptic device is in the range of sensory memory stage. The energy dissipation of the artificial afferents is significantly reduced to 11.9 fJ per spike. Furthermore, the artificial afferents are demonstrated to be capable of recognizing the spatiotemporal information of touch patterns. This work is of great significance for the construction of next-generation neuromorphic sensory network, self-powered biomimetic electronics and intelligent interactive equipment.

Acknowledgment to Reviewers of Journal of Low Power Electronics and Applications in 2020

Peer review is the driving force of journal development, and reviewers are gatekeepers who ensure that Journal of Low Power Electronics and Applications maintains its standards for the high quality of its published papers [...]

Piezoelectric Nanogenerator Based on Lead-Free Flexible PVDF-Barium Titanate Composite Films for Driving Low Power Electronics

Self-powered sensor development is moving towards miniaturization and requires a suitable power source for its operation. The piezoelectric nanogenerator (PENG) is a potential candidate to act as a partial solution to suppress the burgeoning energy demand. The present work is focused on the development of the PENG based on flexible polymer-ceramic composite films. The X-ray spectra suggest that the BTO particles have tetragonal symmetry and the PVDF-BTO composite films (CF) have a mixed phase. The dielectric constant increases with the introduction of the particles in the PVDF polymer and the loss of the CF is much less for all compositions. The BTO particles have a wide structural diversity and are lead-free, which can be further employed to make a CF. An attempt was made to design a robust, scalable, and cost-effective piezoelectric nanogenerator based on the PVDF-BTO CFs. The solvent casting route was a facile approach, with respect to spin coating, electrospinning, or sonication routes. The introduction of the BTO particles into PVDF enhanced the dielectric constant and polarization of the composite film. Furthermore, the single-layered device output could be increased by strategies such as internal polarization amplification, which was confirmed with the help of the polarization-electric field loop of the PVDF-BTO composite film. The piezoelectric nanogenerator with 10 wt% BTO-PVDF CF gives a high electrical output of voltage 7.2 V, current 38 nA, and power density of 0.8 μW/cm2 at 100 MΩ. Finally, the energy harvesting using the fabricated PENG is done by various actives like coin dropping, under air blowing, and finger tapping. Finally, low-power electronics such as calculator is successfully powered by charging a 10 μF capacitor using the PENG device.