A Bio-Inspired Dopamine Model for Robots with Autonomous Decision-Making.

Decision-making systems allow artificial agents to adapt their behaviours, depending on the information they perceive from the environment and internal processes. Human beings possess unique decision-making capabilities, adapting to current situations and anticipating future challenges. Autonomous robots with adaptive and anticipatory decision-making emulating humans can bring robots with skills that users can understand more easily. Human decisions highly depend on dopamine, a brain substance that regulates motivation and reward, acknowledging positive and negative situations. Considering recent neuroscience studies about the dopamine role in the human brain and its influence on decision-making and motivated behaviour, this paper proposes a model based on how dopamine drives human motivation and decision-making. The model allows robots to behave autonomously in dynamic environments, learning the best action selection strategy and anticipating future rewards. The results show the model's performance in five scenarios, emphasising how dopamine levels vary depending on the robot's situation and stimuli perception. Moreover, we show the model's integration into the Mini social robot to provide insights into how dopamine levels drive motivated autonomous behaviour regulating biologically inspired internal processes emulated in the robot.

Biosustainable Multiscale Transparent Nanocomposite Films for Sensitive Pressure and Humidity Sensors.

Light weight, thinness, transparency, flexibility, and insulation are the key indicators for flexible electronic device substrates. The common flexible substrates are usually polymer materials, but their recycling is an overwhelming challenge. Meanwhile, paper substrates are limited in practical applications because of their poor mechanical and thermal stability. However, natural biomaterials have excellent mechanical properties and versatility thanks to their organic-inorganic multiscale structures, which inspired us to design an organic-inorganic nanocomposite film. For this purpose, a bio-inspired multiscale film was developed using cellulose nanofibers with abundant hydrophilic functional groups to assist in dispersing hydroxyapatite nanowires. The thickness of the biosustainable film is only 40 µm, and it incorporates distinctive mechanical properties (strength: 52.8 MPa; toughness: 0.88 MJ m-3) and excellent optical properties (transmittance: 80.0%; haze: 71.2%). Consequently, this film is optimal as a substrate employed for flexible sensors, which can transmit capacitance and resistance signals through wireless Bluetooth, showing an ultrasensitive response to pressure and humidity (for example, responding to finger pressing with 5000% signal change and exhaled water vapor with 4000% signal change). Therefore, the comprehensive performance of the biomimetic multiscale organic-inorganic composite film confers a prominent prospect in flexible electronics devices, food packaging, and plastic substitution.

Applications of a vacuum-actuated multi-material hybrid soft gripper: lessons learnt from RoboSoft manipulation challenge.

Soft grippers are garnering increasing attention for their adeptness in conforming to diverse objects, particularly delicate items, without warranting precise force control. This attribute proves especially beneficial in unstructured environments and dynamic tasks such as food handling. Human hands, owing to their elevated dexterity and precise motor control, exhibit the ability to delicately manipulate complex food items, such as small or fragile objects, by dynamically adjusting their grasping configurations. Furthermore, with their rich sensory receptors and hand-eye coordination that provide valuable information involving the texture and form factor, real-time adjustments to avoid damage or spill during food handling appear seamless. Despite numerous endeavors to replicate these capabilities through robotic solutions involving soft grippers, matching human performance remains a formidable engineering challenge. Robotic competitions serve as an invaluable platform for pushing the boundaries of manipulation capabilities, simultaneously offering insights into the adoption of these solutions across diverse domains, including food handling. Serving as a proxy for the future transition of robotic solutions from the laboratory to the market, these competitions simulate real-world challenges. Since 2021, our research group has actively participated in RoboSoft competitions, securing victories in the Manipulation track in 2022 and 2023. Our success was propelled by the utilization of a modified iteration of our Retractable Nails Soft Gripper (RNSG), tailored to meet the specific requirements of each task. The integration of sensors and collaborative manipulators further enhanced the gripper's performance, facilitating the seamless execution of complex grasping tasks associated with food handling. This article encapsulates the experiential insights gained during the application of our highly versatile soft gripper in these competition environments.

Fractal Resonance: Can Fractal Geometry Be Used to Optimize the Connectivity of Neurons to Artificial Implants?

In parallel to medical applications, exploring how neurons interact with the artificial interface of implants in the human body can be used to learn about their fundamental behavior. For both fundamental and applied research, it is important to determine the conditions that encourage neurons to maintain their natural behavior during these interactions. Whereas previous biocompatibility studies have focused on the material properties of the neuron-implant interface, here we discuss the concept of fractal resonance - the possibility that favorable connectivity properties might emerge by matching the fractal geometry of the implant surface to that of the neurons.To investigate fractal resonance, we first determine the degree to which neurons are fractal and the impact of this fractality on their functionality. By analyzing three-dimensional images of rat hippocampal neurons, we find that the way their dendrites fork and weave through space is important for generating their fractal-like behavior. By modeling variations in neuron connectivity along with the associated energetic and material costs, we highlight how the neurons' fractal dimension optimizes these constraints. To simulate neuron interactions with implant interfaces, we distort the neuron models away from their natural form by modifying the dendrites' fork and weaving patterns. We find that small deviations can induce large changes in fractal dimension, causing the balance between connectivity and cost to deteriorate rapidly. We propose that implant surfaces should be patterned to match the fractal dimension of the neurons, allowing them to maintain their natural functionality as they interact with the implant.

Gustation-Inspired Dual-Responsive Hydrogels for Taste Sensing Enabled by Machine Learning.

Human gustatory system recognizes salty/sour or sweet tastants based on their different ionic or nonionic natures using two different signaling pathways. This suggests that evolution has selected this detection dualism favorably. Analogically, this work constructs herein bioinspired stimulus-responsive hydrogels to recognize model salty/sour or sweet tastes based on two different responses, that is, electrical and volumetric responsivities. Different compositions of zwitter-ionic sulfobetainic N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine (DMAPS) and nonionic 2-hydroxyethyl methacrylate (HEMA) are co-polymerized to explore conditions for gelation. The hydrogel responses upon adding model tastant molecules are explored using electrical and visual de-swelling observations. Beyond challenging electrochemical impedance spectroscopy measurements, naive multimeter electrical characterizations are performed, toward facile applicability. Ionic model molecules, for example, sodium chloride and acetic acid, interact electrostatically with DMAPS groups, whereas nonionic molecules, for example, D(-)fructose, interact by hydrogen bonding with HEMA. The model tastants induce complex combinations of electrical and volumetric responses, which are then introduced as inputs for machine learning algorithms. The fidelity of such a trained dual response approach is tested for a more general taste identification. This work envisages that the facile dual electric/volumetric hydrogel responses combined with machine learning proposes a generic bioinspired avenue for future bionic designs of artificial taste recognition, amply needed in applications.

BioinspiredLLM: Conversational Large Language Model for the Mechanics of Biological and Bio-Inspired Materials.

The study of biological materials and bio-inspired materials science is well established; however, surprisingly little knowledge is systematically translated to engineering solutions. To accelerate discovery and guide insights, an open-source autoregressive transformer large language model (LLM), BioinspiredLLM, is reported. The model is finetuned with a corpus of over a thousand peer-reviewed articles in the field of structural biological and bio-inspired materials and can be prompted to recall information, assist with research tasks, and function as an engine for creativity. The model has proven that it is able to accurately recall information about biological materials and is further strengthened with enhanced reasoning ability, as well as with Retrieval-Augmented Generation (RAG) to incorporate new data during generation that can also help to traceback sources, update the knowledge base, and connect knowledge domains. BioinspiredLLM also has shown to develop sound hypotheses regarding biological materials design and remarkably so for materials that have never been explicitly studied before. Lastly, the model shows impressive promise in collaborating with other generative artificial intelligence models in a workflow that can reshape the traditional materials design process. This collaborative generative artificial intelligence method can stimulate and enhance bio-inspired materials design workflows. Biological materials are at a critical intersection of multiple scientific fields and models like BioinspiredLLM help to connect knowledge domains.

Organic and Biogenic Nanocarriers as Bio-Friendly Systems for Bioactive Compounds' Delivery: State-of-the Art and Challenges.

"Green" strategies to build up novel organic nanocarriers with bioperformance are modern trends in nanotechnology. In this way, the valorization of bio-wastes and the use of living systems to develop multifunctional organic and biogenic nanocarriers (OBNs) have revolutionized the nanotechnological and biomedical fields. This paper is a comprehensive review related to OBNs for bioactives' delivery, providing an overview of the reports on the past two decades. In the first part, several classes of bioactive compounds and their therapeutic role are briefly presented. A broad section is dedicated to the main categories of organic and biogenic nanocarriers. The major challenges regarding the eco-design and the fate of OBNs are suggested to overcome some toxicity-related drawbacks. Future directions and opportunities, and finding "green" solutions for solving the problems related to nanocarriers, are outlined in the final of this paper. We believe that through this review, we will capture the attention of the readers and will open new perspectives for new solutions/ideas for the discovery of more efficient and "green" ways in developing novel bioperformant nanocarriers for transporting bioactive agents.

Cephalopod-inspired polymer composites with mechanically tunable infrared properties.

Cephalopods have evolved an all-soft skin that can rapidly display colors for protection, predation, or communication. Development of synthetic analogs to mimic such color-changing abilities in the infrared (IR) region is pivotal to a variety of technologies ranging from soft robotics, flexible displays, dynamic thermoregulatory systems, to adaptive IR disguise platforms. However, the integration of tissue-like mechanical properties and rapid IR modulation ability into smart materials remains challenging. Here, by drawing inspiration from cephalopod skin, we develop an all-soft adaptive IR composite that can dynamically change its IR appearance upon equiaxial stretching. The biomimetic composite is built entirely from soft materials of liquid metal droplets and elastic elastomer, which are analogs of chromatophores and dermal layer of cephalopod skin, respectively. Driven by externally applied strains, the liquid metal inclusions transition between a contracted droplet state with corrugated surface and an expanded platelet state with relatively smooth surface, enabling dynamic variations in the IR reflectance/emissivity of the composite and ultimately resulting in reversible IR adaption. Strain-actuated flexible IR displays and pneumatically-driven soft devices that can dynamically manipulate their IR appearance are demonstrated as examples of the applicability of this material in emerging adaptive soft electronics.

A Year at the Forefront of Hydrostat Motion.

Currently, in the field of interdisciplinary work in biology, there has been a significant push by the soft robotic community to understand the motion and maneuverability of hydrostats. This Review seeks to expand the muscular hydrostat hypothesis toward new structures, including plants, and introduce innovative techniques to the hydrostat community on new modeling, simulating, mimicking, and observing hydrostat motion methods. These methods range from ideas of kirigami, origami, and knitting for mimic creation to utilizing reinforcement learning for control of bio-inspired soft robotic systems. It is now being understood through modeling that different mechanisms can inhibit traditional hydrostat motion, such as skin, nostrils, or sheathed layered muscle walls. The impact of this Review will highlight these mechanisms, including asymmetries, and discuss the critical next steps toward understanding their motion and how species with hydrostat structures control such complex motions, highlighting work from January 2022 to December 2022.

Maneuvering on non-Newtonian fluidic terrain: a survey of animal and bio-inspired robot locomotion techniques on soft yielding grounds.

Frictionally yielding media are a particular type of non-Newtonian fluids that significantly deform under stress and do not recover their original shape. For example, mud, snow, soil, leaf litters, or sand are such substrates because they flow when stress is applied but do not bounce back when released. Some robots have been designed to move on those substrates. However, compared to moving on solid ground, significantly fewer prototypes have been developed and only a few prototypes have been demonstrated outside of the research laboratory. This paper surveys the existing biology and robotics literature to analyze principles of physics facilitating motion on yielding substrates. We categorize animal and robot locomotion based on the mechanical principles and then further on the nature of the contact: discrete contact, continuous contact above the material, or through the medium. Then, we extract different hardware solutions and motion strategies enabling different robots and animals to progress. The result reveals which design principles are more widely used and which may represent research gaps for robotics. We also discuss that higher level of abstraction helps transferring the solutions to the robotics domain also when the robot is not explicitly meant to be bio-inspired. The contribution of this paper is a review of the biology and robotics literature for identifying locomotion principles that can be applied for future robot design in yielding environments, as well as a catalog of existing solutions either in nature or man-made, to enable locomotion on yielding grounds.

Recent Advances in Sources of Bio-Inspiration and Materials for Robotics and Actuators.

Bionic robotics and actuators have made dramatic advancements in structural design, material preparation, and application owing to the richness of nature and innovative material design. Appropriate and ingenious sources of bio-inspiration can stimulate a large number of different bionic systems. After millennia of survival and evolutionary exploration, the mere existence of life confirms that nature is constantly moving in an evolutionary direction of optimization and improvement. To this end, bio-inspired robots and actuators can be constructed for the completion of a variety of artificial design instructions and requirements. In this article, the advances in bio-inspired materials for robotics and actuators with the sources of bio-inspiration are reviewed. The specific sources of inspiration in bionic systems and corresponding bio-inspired applications are summarized first. Then the basic functions of materials in bio-inspired robots and actuators is discussed. Moreover, a principle of matching biomaterials is creatively suggested. Furthermore, the implementation of biological information extraction is discussed, and the preparation methods of bionic materials are reclassified. Finally, the challenges and potential opportunities involved in finding sources of bio-inspiration and materials for robotics and actuators in the future is discussed.

Biomimetic polymer fibers-function by design.

Biomimicry applies the fundamental principles of natural materials, processes, and structures to technological applications. This review presents the two strategies of biomimicry-bottom-up and top-down approaches, using biomimetic polymer fibers and suitable spinning techniques as examples. The bottom-up biomimicry approach helps to acquire fundamental knowledge on biological systems, which can then be leveraged for technological advancements. Within this context, we discuss the spinning of silk and collagen fibers due to their unique natural mechanical properties. To achieve successful biomimicry, it is imperative to carefully adjust the spinning solution and processing parameters. On the other hand, top-down biomimicry aims to solve technological problems by seeking solutions from natural role models. This approach will be illustrated using examples such as spider webs, animal hair, and tissue structures. To contextualize biomimicking approaches in practical applications, this review will give an overview of biomimetic filter technologies, textiles, and tissue engineering.

Bioinspired medical needles: a review of the scientific literature.

Needles are commonly used in medical procedures. However, current needle designs have some disadvantages. Therefore, a new generation of hypodermic needles and microneedle patches drawing inspiration from mechanisms found in nature (i.e. bioinspiration) is being developed. In this systematic review, 80 articles were retrieved from Scopus, Web of Science, and PubMed and classified based on the strategies for needle-tissue interaction and propulsion of the needle. The needle-tissue interaction was modified to reduce grip for smooth needle insertion or enlarge grip to resist needle retraction. The reduction of grip can be achieved passively through form modification and actively through translation and rotation of the needle. To enlarge grip, interlocking with the tissue, sucking the tissue, and adhering to the tissue were identified as strategies. Needle propelling was modified to ensure stable needle insertion, either through external (i.e. applied to the prepuncturing movement of the needle) or internal (i.e. applied to the postpuncturing movement of the needle) strategies. External strategies include free-hand and guided needle insertion, while friction manipulation of the tissue was found to be an internal strategy. Most needles appear to be using friction reduction strategies and are inserted using a free-hand technique. Furthermore, most needle designs were inspired by insects, specifically parasitoid wasps, honeybees, and mosquitoes. The presented overview and description of the different bioinspired interaction and propulsion strategies provide insight into the current state of bioinspired needles and offer opportunities for medical instrument designers to create a new generation of bioinspired needles.

Energy considerations and flow fields over whiffling-inspired wings.

Some bird species fly inverted, or whiffle, to lose altitude. Inverted flight twists the primary flight feathers, creating gaps along the wing's trailing edge and decreasing lift. It is speculated that feather rotation-inspired gaps could be used as control surfaces on uncrewed aerial vehicles (UAVs). When implemented on one semi-span of a UAV wing, the gaps produce roll due to the asymmetric lift distribution. However, the understanding of the fluid mechanics and actuation requirements of this novel gapped wing were rudimentary. Here, we use a commercial computational fluid dynamics solver to model a gapped wing, compare its analytically estimated work requirements to an aileron, and identify the impacts of key aerodynamic mechanisms. An experimental validation shows that the results agree well with previous findings. We also find that the gaps re-energize the boundary layer over the suction side of the trailing edge, delaying stall of the gapped wing. Further, the gaps produce vortices distributed along the wingspan. This vortex behavior creates a beneficial lift distribution that produces comparable roll and less yaw than the aileron. The gap vortices also inform the change in the control surface's roll effectiveness across angle of attack. Finally, the flow within a gap recirculates and creates negative pressure coefficients on the majority of the gap face. The result is a suction force on the gap face that increases with angle of attack and requires work to hold the gaps open. Overall, the gapped wing requires higher actuation work than the aileron at low rolling moment coefficients. However, above rolling moment coefficients of 0.0182, the gapped wing requires less work and ultimately produces a higher maximum rolling moment coefficient. Despite the variable control effectiveness, the data suggest that the gapped wing could be a useful roll control surface for energy-constrained UAVs at high lift coefficients.

A bio-inspired expandable soft suction gripper for minimal invasive surgery-an explorative design study.

Gripping slippery and flexible tissues during minimal invasive surgery (MIS) is often challenging using a conventional tissue gripper. A force grip has to compensate for the low friction coefficient between the gripper's jaws and the tissue surface. This study focuses on the development of a suction gripper. This device applies a pressure difference to grip the target tissue without the need to enclose it. Inspiration is taken from biological suction discs, as these are able to attach to a wide variety of substrates, varying from soft and slimy surfaces to rigid and rough rocks. Our bio-inspired suction gripper is divided into two main parts: (1) the suction chamber inside the handle where vacuum pressure is generated, and (2) the suction tip that attaches to the target tissue. The suction gripper fits through a∅10 mm trocar and unfolds in a larger suction surface when being extracted. The suction tip is structured in a layered manner. The tip integrates five functions in separate layers to allow for safe and effective tissue handling: (1) foldability, (2) air-tightness, (3) slideability, (4) friction magnification and (5) seal generation. The contact surface of the tip creates an air-tight seal with the tissue and enhances frictional support. The suction tip's shape grip allows for the gripping of small tissue pieces and enhances its resistance against shear forces. The experiments illustrated that our suction gripper outperforms man-made suction discs, as well as currently described suction grippers in literature in terms of attachment force (5.95±0.52 N on muscle tissue) and substrate versatility. Our bio-inspired suction gripper offers the opportunity for a safer alternative to the conventional tissue gripper in MIS.

Design for Robustness: Bio-Inspired Perspectives in Structural Engineering.

Bio-inspired solutions are widely adopted in different engineering disciplines. However, in structural engineering, these solutions are mainly limited to bio-inspired forms, shapes, and materials. Nature is almost completely neglected as a source of structural design philosophy. This study lists and discusses several bio-inspired solutions classified into two main classes, i.e., compartmentalization and complexity, for structural robustness design. Different examples are provided and mechanisms are categorized and discussed in detail. Some provided ideas are already used in the current structural engineering research and practice, usually without focus on their bio-analogy. These solutions are revisited and scrutinized from a bio-inspired point of view, and new aspects and possible improvements are suggested. Moreover, novel bio-inspired concepts including delayed compartmentalization, active compartmentalization, compartmentalization in intact parts, and structural complexity are also propounded for structural design under extreme loading conditions.

Early career scientists converse on the future of soft robotics.

During the recent decade, we have witnessed an extraordinary flourishing of soft robotics. Rekindled interest in soft robots is partially associated with the advances in manufacturing techniques that enable the fabrication of sophisticated multi-material robotic bodies with dimensions ranging across multiple length scales. In recent manuscripts, a reader might find peculiar-looking soft robots capable of grasping, walking, or swimming. However, the growth in publication numbers does not always reflect the real progress in the field since many manuscripts employ very similar ideas and just tweak soft body geometries. Therefore, we unreservedly agree with the sentiment that future research must move beyond "soft for soft's sake." Soft robotics is an undoubtedly fascinating field, but it requires a critical assessment of the limitations and challenges, enabling us to spotlight the areas and directions where soft robots will have the best leverage over their traditional counterparts. In this perspective paper, we discuss the current state of robotic research related to such important aspects as energy autonomy, electronic-free logic, and sustainability. The goal is to critically look at perspectives of soft robotics from two opposite points of view provided by early career researchers and highlight the most promising future direction, that is, in our opinion, the employment of soft robotic technologies for soft bio-inspired artificial organs.

Erratum: Transient bio-inspired gliders with embodied humidity responsive actuators for environmental sensing.

[This corrects the article DOI: 10.3389/frobt.2022.1011793.].

Design and Biomimicry: A Review of Interconnections and Creative Potentials.

The study and application of biological knowledge favor the creation of innovative projects in several areas, so it is necessary to better understand the use of these resources specifically in the field of design. Thus, a systematic review was undertaken to identify, describe, and analyze the contributions of biomimicry to design. For this purpose, the integrative systematic review model, called the Theory of Consolidated Meta-Analytical Approach, was used, carrying out a search on the Web of Science with the descriptors "design" and "biomimicry". For the period from 1991 to 2021, 196 publications were retrieved. The results were organized according to areas of knowledge, countries, journals, institutions, authors, and years. Citation, co-citation, and bibliographic coupling analyses were also performed. The investigation highlighted the following research emphases: the conception of products, buildings, and environments; the exploration of natural structures and systems to create materials and technologies; the use of biomimetic creative tools in product design; and projects focused on saving resources and implementing sustainability. It was noted that there was a tendency for authors to adopt a problem-based approach. It was concluded that the study of biomimicry can stimulate the development of multiple skills in design, improving creativity, and enhancing the potential integration of sustainability into production cycles.