Geraniaceae seeds represent a role model in soft robotics thanks to their ability to move autonomously across and into the soil driven by humidity changes. The secret behind their mobility and adaptivity is embodied in the hierarchical structures and anatomical features of the biological hygroscopic tissues, geometrically designed to be selectively responsive to environmental humidity. Following a bioinspired approach, the internal structure and biomechanics of Pelargonium appendiculatum (L.f.) Willd seeds are investigated to develop a model for the design of a soft robot. The authors exploit the re-shaping ability of 4D printed materials to fabricate a seed-like soft robot, according to the natural specifications and model, and using biodegradable and hygroscopic polymers. The robot mimics the movement and performances of the natural seed, reaching a torque value of ≈30 µN m, an extensional force of ≈2.5 mN and it is capable to lift ≈100 times its own weight. Driven by environmental humidity changes, the artificial seed is able to explore a sample soil, adapting its morphology to interact with soil roughness and cracks.

Dataset I-Seed_DS1 focus on bioengineering investigations of plant seed models, to define useful specifications for the design of the artificial systems in terms of multi-functional materials and morphological computation. Task 3.1. Erodium cicutarium seeds: from natural features to robotic specifics. Task 3.2. Samara seeds: from natural features to robotic specifics

This chapter provides an overview of the physics, materials and devices conceived so far for the conversion of waste heat into power, particularly based on the Colloidal Energetic Systems concept. Colloids can be used exploiting their huge variety of phenomena embedded at the nanoscale, to convert low grade energy into electrical power, by exploiting thermomagnetic advection, triboelectric, pyroelectric, photothermal, thermoelectric and thermogalvanic effects.

Combined photothermal‐hygroscopic effects enable novel materials actuation strategies based on renewable and sustainable energy sources such as sunlight. Plasmonic nanoparticles have gained considerable interest as photothermal agents, however, the employment in sunlight‐driven photothermal‐hygroscopic actuators is still bounded, mainly due to the limited absorbance once integrated into nanocomposite actuators and the restricted plasmonic peaks amplitude (compared to the solar spectrum). Herein, the design and fabrication of an AgNPs‐based plasmonic photothermal‐hygroscopic actuator integrated with printed cellulose tracks are reported (bioinspired to Geraniaceae seeds structures). The nanocomposite is actuated by sunlight power density (i.e., 1 Sun = 100 mW cm −2 ). The plasmonic AgNPs are in situ synthesized on the PDMS surface through a one‐step and efficient fluoride‐assisted synthesis (surface coverage ≈40%). The nanocomposite has a broadband absorbance in the VIS range (>1) and a Photothermal Conversion Efficiency ≈40%. The actuator is designed exploiting a mechanical model that predicted the curvature and forces, featuring a ≈6.8 ± 0.3 s response time, associated with a ≈43% change in curvature and a 0.76 ± 0.02 mN force under 1 Sun irradiation. The plasmonic nanocomposite actuator can be used for multiple tasks, as hinted through illustrative soft robotics demonstrators, thus fostering a bioinspired approach to developing embodied energy systems driven by sunlight.

Soft Robotics In article number 2205146, Stefano Mariani, Nicola M. Pugno, Barbara Mazzolai, and co-workers develop a seed-inspired soft robot using 4D printed biodegradable polymers. Driven by humidity changes, the artificial seed adapts its morphology to interact with soil roughness and cracks, exploring a sample soil. In perspective, the soft robot shows great potential as a battery-free wireless tool for environmental monitoring.

Visual sensors for relative humidity (RH) are of interest for distributed and autonomous environmental monitoring. Most of the visual humidity sensors are based on colorimetric sensing through the employment of hygroscopic inorganic pigments or photonic crystals (PCs). However, the toxicity of some inorganic pigments poses a risk to the environment especially if dispersed during in-situ measurements. On the other hand, the angledependent structural colours reading of the PCs, make these devices non suitable for autonomous and in-situ environmental monitoring. Here, we report the first visual humidity sensor using an artificial and hygroscopic seed-like robot (I-SeedPel) recently (2023) developed by our group for hygro-driven environmental exploration (https://doi.org/10. 1002/advs.202205146). The I-SeedPel design is bioinspired to the hygroscopic and layered tissues of the Pelargonium appendiculatum seed and fabricated through additive manufacturing techniques using biodegradable polymers. The hygromechanical response of the I-SeedPel generates a reversible change of the geometrical features in the artificial seed structure (i.e., awn's angular displacement and diameter variation) related to the RH. The variation of the geometric properties can be quantified and correlated to RH in a wide range (30-90 %), with an accuracy of 97-98 %, with a resolution of 0.17-0.52 % of RH and a good reproducibility (average RSD = 14.7 %).

The combined effects of thermo-sensitive and photothermal materials present novel actuation strategies for wireless application and the use of sustainable energy sources, such as the sunlight. To understand the operating features of multifunctional materials, bioinspired multi-layer actuators represent a simple solution as a testing platform. Here, we report the fabrication of a bilayer photothermal and biodegradable bending actuator, based on thermal expansion of polycaprolactone-lignin blend, 3D printed on cellulose acetate substrate. When the actuator is irradiated with 300 mW/cm2 of simulated solar irradiance, it shows a change in curvature of 25.34

In our treatise [1], we propose an alternative definition of magnetic body force in opposition to the most common definition proposed by Rosenweig [2] and widely used in contemporary scientific literature. We consider any ferrofluid (FF) as an ensemble of infinitesimal magnetic dipoles, the magnetite nanoparticles (NPs), uniformly dispersed in colloidal form through a magnetically neutral carrier solvent (oil-based as kerosene, or water-based). This consideration is based on solid phenomenological assumptions, since due to quantum and size effects, the FF shows superparamagnetic behaviour [3]: knowing that the average size of the magnetic domains depends on exchange energy, magnetocrystalline anisotropy energy and magnetic dipolar energy [3], when the volume of the magnetic element drops below a critical value, it is no longer energetically favourable to include multiple domains and domain walls. Hence, the magnetic material below the critical size stays permanently magnetized to a value close to its saturation magnetization. In this case, we can state that the material is a singledomain structure. The mean diameter of magnetic NPs in FF is below its critical diameter, meaning that each NP can be considered as a single-domain structure and can be represented as an infinitesimal magnetic dipole dispersed in a non-interacting carrier fluid. Therefore, from a purely phenomenological point of view, we believe that the dipole approximation can be considered valid in the case of FFs. According to previous considerations, it is now evident why it is possible to model a single magnetic NP as an infinitesimal magnetic dipole. As discussed in [1], Griffiths proposed

Owing to the waste of energy originated by any physical or chemical process, approaches for reducing the energy losses have been conceived and, nowadays, energy recovery and conversion systems represent a worldwide‐recognized solution. The advent of colloidal‐based cybernetic systems highlights the essential role of energy harvesting, storage, and management capabilities coped by colloidal energetic systems. In this work, an alternative to thermoelectricity generation is demonstrated by means of a magnetic colloid based on Fe 3 O 4 nanoparticles (NPs). The ferrofluid (FF) tribo‐ and pyroelectric features are explored in order to increase the amount of harvested energy. The findings suggest that the FF shows both triboelectric and pyroelectric charge displacement. A capacitive electrode is more efficient for accumulating potentials up to 48 V developed by triboelectricity while a resistive one is essential to collect pyroelectric charges up to 22 nA, which helped to estimate the FF pyroelectric coefficient, reaching the remarkable value of 25.2 μ Cm −2 K −1 . A simplified equivalent model of the inductive setup is proposed, suggesting that increasing the fluid temperature a reduction of FF inductance due to demagnetization effects occurs.

Plants have evolved different mechanisms to disperse from parent plants and improve germination to sustain their survival. The study of seed dispersal mechanisms, with the related structural and functional characteristics, is an active research topic for ecology, plant diversity, climate change, as well as for its relevance for material science and engineering. The natural mechanisms of seed dispersal show a rich source of robust, highly adaptive, mass and energy efficient mechanisms for optimized passive flying, landing, crawling and drilling. The secret of seeds mobility is embodied in the structural features and anatomical characteristics of their tissues, which are designed to be selectively responsive to changes in the environmental conditions, and which make seeds one of the most fascinating examples of morphological computation in Nature. Particularly clever for their spatial mobility performance, are those seeds that use their morphology and structural characteristics to be carried by the wind and dispersed over great distances (i.e. "winged" and "parachute" seeds), and seeds able to move and penetrate in soil with a self-burial mechanism driven by their hygromorphic properties and morphological features. By looking at their motion mechanisms, new design principles can be extracted and used as inspiration for smart artificial systems endowed with embodied intelligence. This mini-review systematically collects, for the first time together, the morphological, structural, biomechanical and aerodynamic information from selected plant seeds relevant to take inspiration for engineering design of soft robots, and discusses potential future developments in the field across material science, plant biology, robotics and embodied intelligence.

Energy consumption levels show a never‐ending increase since the industrial era. Toward sustainability objectives, it is of outstanding importance to reduce the amount of wasted energy, that typically comes as waste heat, as a consequence of nonunitary efficiency of any thermodynamic process. Herein, a breakthrough in conversion of low enthalpy heat into electricity is presented, based on a liquid state device that operates through multiphysics effects: thermomagnetic advection, triboelectricity, pyroelectricity, and Ludwig–Sorét effect. A synergistic interaction between ferroelectric surfaces and a complex composition colloidal suspension is evidenced, owing to an enhancement of the generated potential of 365% in comparison with pyroelectric effect and 267% in comparison with triboelectric effect, while the current extracted is 54% higher than the pyroelectric effect only and the power extracted by induction remains substantially unperturbed. The impact of this technology on society is also analyzed, on the basis of a set of practical applications, by means of a computational analysis.

The modeling of electromagnetically-operated fluids represents a technologically relevant domain, yet a scientifically challenging study. In particular, real fluids typically fall between existing consolidated models, such as hydrodynamics, electrohydrodynamics, magnetohydrodynamics and ferrohydrodynamics. A key element for the description of dynamic phenomena is the so called magnetic body force, whose role is that of shaping electromagnetic forces under simplified schemes and capturing the broadest phenomena possible. In this study a simple model equation is proposed and justified in light of existing literature, and the benefits of decoupling the effects of temperature and external magnetic field are discussed making reference to the advantages gained in numerical simulations.

Energy consumption, environmental impact, and sustainability have risen fast through the ranks, achieving the first places in driving investments, policies, and concerns of all countries at any developmental stage. Energy transformation, though, must cope with nonunitary efficiency of devices and processes, which results in a distributed production of waste heat. A reduction of emissions, implying a conversion of waste heat to more noble forms of energy and a concurrent increase in efficiency of the same devices and processes, is of paramount importance. In view of the enthalpy content and distribution of the different sources of waste heat, low‐grade/low‐enthalpy sources below 200 °C are considered the most fertile field for research and development, with an impressive industrial growth rate. Thermodynamic cycles and thermal conversion devices based on the most relevant physical effects are herein introduced and briefly described, including both solutions that already achieved industrial maturity and less developed systems and devices whose study is still in progress. A specific focus on three application domains, selected due to their economic relevance, is done: industrial processes for the vast energy and capital availability, automotive sector for its permeation, and wearable devices for the market size. Limits and opportunities are critically discussed.

Nowadays, energy-related issues are of paramount importance. Every energy transformation process results in the production of waste heat that can be harvested and reused, representing an ecological and economic opportunity. Waste heat to power (WHP) is the process of converting the waste heat into electricity. A novel approach is proposed based on the employment of liquid nano colloids. In this work, the triboelectric characterization of TiO(2)nanoparticles dispersed in pure water and flowing in a fluorinated ethylene propylene (FEP) pipe was conducted. The idea is to exploit the waste heat to generate the motion of colloidal TiO(2)through a FEP pipe. By placing an Al ring electrode in contact with the pipe, it was possible to accumulate electrostatic charges due to the triboelectric effect between the fluid and the inner pipe walls. A peristaltic pump was used to drive and control the flow in order to evaluate the performances in a broad fluid dynamic spectrum. The system generated as output relatively high voltages and low currents, resulting in extracted power ranging between 0.4 and 0.6 nW. By comparing the power of pressure loss due to friction with the extracted power, the electro-kinetic efficiency was estimated to be 20%.