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Scientists have identified turgor-based actuation as a fundamental mechanism in plant movements. Plant cell turgor is generated by water influx due to the osmolyte concentration gradient through the cell wall and the plasma membrane behaving as an osmotic barrier. Previous studies have focused on turgor modulation with respect to potassium chloride (KCl) concentration changes, although KCl is not efficiently retained in the cell, and many other compounds, including L-glutamine (L-Gln) and D-glucose (D-Glc), are present in the cytosol. In fact, the contributions of other osmolytes to turgor dynamics remain to be elucidated. Here, we show the association of osmolytes and their consequent cooperative effects on the time-dependent turgor profile generated in a model cytosol consisting of KCl, D-Glc and L-Gln at experimentally measured plant motor/generic cell concentrations and at modified concentrations. We demonstrate the influence and association of the osmolytes using osmometry and NMR measurements. We also show, using a plant cell-inspired device we previously developed, that osmolyte complexes, rather than single osmolytes, permit to obtain higher turgor required by plant movements. We provide quantitative cues for deeper investigations of osmolyte transport for plant movement, and reveal the possibility of developing osmotic actuators exploiting a dynamically varying concentration of osmolytes.

The largest existing biological interface, the surface of living plants, as it stands is capable of converting mechanical energy into electricity based on a combination of contact electrification and electrostatic induction on the plant surface and its inner tissue. Herein, the first design strategies are reported for living plant‐based wind energy harvesting systems that use this effect and that are capable of harvesting simultaneously from multiple leaves of a single plant to upscale the energy output. This is the first study under outdoor‐relevant conditions in a controlled test environment that relates plant‐based energy conversion to wind speed and wind direction as well as parameters such as the environmental humidity. Increasing the wind speed not only leads to higher power but also low winds of 2 m s−1 and less can be converted into storable electricity. The plant‐hybrid generators are moreover capable of converting wind from multiple directions by exploiting the naturally multiplex leaf orientations and the plants can directly power light‐emitting diodes (LEDs) and a digital thermometer. The results draw attention to the opportunity to obtain living plant‐hybrid generators, e.g., for applications in constituting environmental sensor networks. [ABSTRACT FROM AUTHOR]

Plants use many strategies to move efficiently in soil, such as growth from the tip, tropic movements, and morphological changes. In this paper, we propose a method to translate morphological features of Zea mays roots into a new design of soft robots that will be able to move in soil. The method relies on image processing and curve fitting techniques to extract the profile of Z. mays primary root. We implemented an analytic translation of the root profile in a 3D model (CAD) to fabricate root-like probes by means of 3D printing technology. Then, we carried out a comparative analysis among the artificial root-like probe and probes with different tip shapes (cylindrical, conical, elliptical, and parabolic) and diameters (11, 9, 7, 5, and 3 mm). The results showed that the energy consumption and the penetration force of the bioinspired probe are better with respect to the other shapes for all the diameters of the developed probes. For 100 mm of penetration depth and 7 mm of probe diameter, the energy consumption of the bioinspired probe is 89% lesser with respect to the cylindrical probe and 26% lesser with respect to the conical probe. The penetration performance of the considered tip shapes was evaluated also by means of numerical simulations, obtaining a good agreement with the experimental results. Additional investigations on plant root morphology, movement strategies, and material properties can allow the development of innovative bioinspired solutions exploitable in challenging environments. This research can bring to breakthrough scenarios in different fields, such as exploration tasks, environmental monitoring, geotechnical studies, and medical applications. [ABSTRACT FROM AUTHOR]

Osmotic actuation is a ubiquitous plant-inspired actuation strategy that has a very low power consumption but is capable of generating effective movements in a wide variety of environmental conditions. In light of these features, we aimed to develop a novel, low-power-consumption actuator that is capable of generating suitable forces during a characteristic actuation time on the order of a few minutes. Based on the analysis of plant movements and on osmotic actuation modeling, we designed and fabricated a forward osmosis-based actuator with a typical size of 10 mm and a characteristic time of 2–5 minutes. To the best of our knowledge, this is the fastest osmotic actuator developed so far. Moreover, the achieved timescale can be compared to that of a typical plant cell, thanks to the integrated strategy that we pursued by concurrently addressing and solving design and material issues, as paradigmatically explained by the bioinspired approach. Our osmotic actuator produces forces above 20 N, while containing the power consumption (on the order of 1 mW). Furthermore, based on the agreement between model predictions and experimental observations, we also discuss the actuator performance (including power consumption, maximum force, energy density and thermodynamic efficiency) in relation to existing actuation technologies. In light of the achievements of the present study, the proposed osmotic actuator holds potential for effective exploitation in bioinspired robotics systems. [ABSTRACT FROM AUTHOR]

Moving in an unstructured environment such as soil requires approaches that are constrained by the physics of this complex medium and can ensure energy efficiency and minimize friction while exploring and searching. Among living organisms, plants are the most efficient at soil exploration, and their roots show remarkable abilities that can be exploited in artificial systems. Energy efficiency and friction reduction are assured by a growth process wherein new cells are added at the root apex by mitosis while mature cells of the root remain stationary and in contact with the soil. We propose a new concept of root-like growing robots that is inspired by these plant root features. The device penetrates soil and develops its own structure using an additive layering technique: each layer of new material is deposited adjacent to the tip of the device. This deposition produces both a motive force at the tip and a hollow tubular structure that extends to the surface of the soil and is strongly anchored to the soil. The addition of material at the tip area facilitates soil penetration by omitting peripheral friction and thus decreasing the energy consumption down to 70% comparing with penetration by pushing into the soil from the base of the penetration system. The tubular structure provides a path for delivering materials and energy to the tip of the system and for collecting information for exploratory tasks. [ABSTRACT FROM AUTHOR]

The leaves of living plants are the largest biointerface existing on earth that could now be utilized to generate electricity. In their article number 1806689, Fabian Meder, Barbara Mazzolai, and co‐workers investigate how charge generation at the leaf surface occurs and use the effect to construct living plant‐hybrid energy converters for harvesting wind power. [ABSTRACT FROM AUTHOR]

Progress towards green and autonomous energy sources includes harnessing living systems and biological tissue. It is recently discovered that the cuticle‐cellular tissue bilayer in higher plant leaves functions as an integrated triboelectric generator conductor couple capable of converting mechanical stimuli into electricity. Here, it is investigated for the first time, in detail how charge generation at the living plant leaf occurs, and it is shown how whole plants could be used in plant‐hybrid wind‐energy harvesting systems. The charge accumulation and compensation in and ex vivo on Rhododendron leaves by Kelvin force microscopy is verified, revealing that charges are induced and transported in living plant tissue whereas charges remain unbalanced and trapped on dead leaves of the same species. A distinct sensing functionality and opportunity to upscale power output is given as electrical signals are species, touch‐material, and dose‐dependent and scale with frequency, impact force, and area. It is shown that also purely natural mechanical stimuli by wind or self‐touching of leaves are converted into electrical signals by a triboelectric mechanism. The entirely plant‐enabled and autonomous energy conversion can be used to directly drive light emitting diodes, charge a capacitor, and harvest wind‐energy with promise for new energy sources based on the Plant Kingdom. Living plants integrate energy conversion and conduction networks in a single organism that can be used as natural triboelectric generators. It is investigated in detail how charge generation occurs at the plant leaf cuticle, world's largest biointerface, and the effect is used to construct plant‐hybrid energy converters, e.g., for wind‐energy harvesting. [ABSTRACT FROM AUTHOR]

An emerging challenge in soft robotics research is to reveal mechanical solicitations in a soft body. Nature provides amazing clues to develop unconventional components that are capable of compliant interactions with the environment and living beings, avoiding mechanical and algorithmic complexity of robotic design. We inspire from plant-root mechanoperception and develop a strategy able to reveal bending and applied force in a soft body with only two sensing elements of the same kind, and a null computational effort. The stretching processes that lead to opposite tissue deformations on the two sides of the root wall are emulated with two tactile sensing elements, made of soft and stretchable materials, which conform to reversible changes in the shape of the body they are built in and follow its deformations. Comparing the two sensory responses, we can discriminate the concave and the convex side of the bent body. Hence, we propose a new strategy to reveal in a soft body the maximum bending angle (or the maximum deflection) and the externally applied force according to the body's mechanical configuration. [ABSTRACT FROM AUTHOR]