This PDF file contains the front matter associated with SPIE Proceedings Volume 12041 including the Title Page, Copyright information, and Table of Contents.

Nanotechnology-based dental composites, see Tokuyama Dental's OMNICHROMA, can address the issue of color mismatch between tooth and filling. Similar to a chameleon, the filling can match the color of the surrounding enamel. We thoroughly investigated the nanostructure of the composite and the related optical properties using electron microscopy, synchrotron radiation-based nanotomography, small-angle X-ray scattering and optical transmission measurements. The spherical silica-zirconia fillers show a size of 260 nm and form micrometer-sized spherical domains of close-packed nanospheres. The aim of the study is to quantify the chameleon effect and discuss possible paths towards biomimetic anisotropic dental composites with improved color matching.

A novel magnetochromic elastomer with a strong and rapid magnetochromic effect has been developed. In the system, citric acid surface-functionalized magnetic nanoparticles (MNPs) are dissolved in poly(ethylene glycol) (PEG-200) and ultrasonicated into an emulsion with polydimethylsiloxane (PDMS) by speedmixing. The MNPs are shown to change from random to field-aligned under an external magnetic field and thus enables an on/off function. The developed elastomer shows a great potential for a wide range of applications, such as sensors and anticounterfeiting labels.

The aye-aye (Daubentonia madagascariensis) is a nocturnal lemur native to the island of Madagascar with a special thin middle finger. The aye-aye’s third digit (the slenderest one) has a remarkably specific adaptation, allowing it to perform tap-scanning (Finger tapping) to locate small cavities beneath tree bark and extract woodboring larvae from it. This finger, as an exceptional active acoustic actuator, makes an aye-aye’s biological system an attractive model for Nondestructive Evaluation (NDE) methods and robotic systems. Despite the important aspects of the topic in engineering sensory and NDE, little is known about the mechanism and movement of this unique finger. In this paper a simplified kinematic model was proposed to simulate the aye-aye’s middle finger motion.

Fish swimming is a promising source of inspiration for novel and efficient propulsion mechanisms for autonomous underwater vehicles, as fishes swim with excellent energy efficiency and high maneuverability. Among the locomotion strategies of aquatic animals, the swimming mode of batoids is one of the most interesting, as these fishes swim with high energy efficiency, and they are capable of performing maneuvers with great agility. These advantages are mainly due to the fin geometry and the kinematics of their movement. The fish develops a traveling wave from the leading edge to the trailing edge of the fin, the amplitude of which increases towards the tip of the fin. This wave pushes the water backward, giving the fish a forward thrust due to momentum conservation. The motion of the fin of a cownose ray has been studied, and a biomimetic swimming robot inspired by the cownose ray has been designed and realized. Each fin is made of silicone sheets, and it is moved by three mechanisms whose kinematics replicate the fin deformation. Each mechanism is driven by an independent servomotor, creating a traveling wave on the fin whose frequency, wavelength, and amplitude can be modulated. The motors, battery, and electronics are housed in the central body of the robot, which is rigid. This paper describes the robot’s design and construction.

Fluidic artificial muscles (FAMs) have emerged as a viable and popular robotic actuation technique due to their low cost, compliant nature, and high force-to-weight-ratio. In recent years, the concept of variable recruitment has emerged as a way to improve the efficiency of conventional hydraulic robotic systems. In variable recruitment, groups of FAMs are bundled together and divided into individual motor units. Each motor unit can be activated independently, which is similar to the sequential activation pattern observed in mammalian muscle. Previous researchers have performed quasistatic characterizations of variable recruitment bundles and some simple dynamic analyses and experiments with a simple 1- DOF robot arm. We have developed a linear hydraulic characterization testing platform that will allow for the testing of different types of variable recruitment bundle configurations under different loading conditions. The platform consists of a hydraulic drive cylinder that acts as a cyber-physical hardware-in-the-loop dynamic loading emulator and interfaces with the variable recruitment bundle. The desired inertial, damping and stiffness properties of the emulator can be prescribed and achieved through an admittance controller. In this paper, we test the ability of this admittance controller to emulate different inertial, stiffness, and damping properties in simulation and demonstrate that it can be used in hardware through a proof-of-concept experiment. The primary goal of this work is to develop a unique testing setup that will allow for the testing of different FAM configurations, controllers, or subsystems and their responses to different dynamic loads before they are implemented on more complex robotic systems.

Artificial skin is a synthetic membrane structure that mimics the flexibility and sensory functions of biological skin. Similar to receptors in biological skin sending signals to neurons in the brain, artificial skin needs sensors capable of converting information into electrical signals and transmitting them. Artificial skins are of increasing interest for prosthetics, soft robotics, virtual reality, wearable devices, and emerging medical applications, such as potentially reducing the number of amputations due to foot ulcers found in 25% of diabetic individuals. In this work, we successfully demonstrated a selforganizing map based on Kohonen artificial neural network to mimic how a brain distinguishes and pinpoints stimuli on skin. An artificial skin was developed from low-methoxyl pectin, a natural substance found in plants, which resulted in flexible films whose electrical conductivity increased with temperature. After optimization, with 10V bias, a nearly 10,000% increase in current was obtained as temperature increased from room temperature to T≈78 °C. Differential voltage measurement data was used to train the Kohonen artificial neural network. Various learning rates, sigma values, and different iterations were investigated, and results in a representative two-dimensional map were successfully obtained, reflecting the topology of the pectin artificial skin with a distinct hot spot. The results demonstrate the ability of this combined method of a few electrodes and Kohonen maps to mimic how a brain distinguishes and pinpoints stimuli on the skin.

In this study, the implementation and performance of bipennate topology fluidic artificial muscle (FAM) bundles operating under varying boundary conditions is investigated and quantified experimentally. Soft actuators are of great interest to design engineers due to their inherent flexibility and potential to improve safety in human robot interactions. McKibben fluidic artificial muscles are soft actuators which exhibit high force to weight ratios and dynamically replicate natural muscle movement. These features, in addition to their low fabrication cost, set McKibben FAMs apart as attractive components for an actuation system. Previous studies have shown that there are significant advantages in force and contraction outputs when using bipennate topology FAM bundles as compared to the conventional parallel topology1 . In this study, we will experimentally explore the effects of two possible boundary conditions imposed on FAMs within a bipennate topology. One boundary condition is to pin the muscle fiber ends with fixed pin spacings while the other is biologically inspired and constrains the muscle fibers to remain in contact. This paper will outline design considerations for building a test platform for bipennate fluidic artificial muscle bundles with varying boundary conditions and present experimental results quantifying muscle displacement and force output. These metrics are used to analyze the tradespace between the two boundary conditions and the effect of varying pennation angles.

The aye-aye (Daubentonia madagascariensis) is the largest nocturnal primate in the world and possesses a number of distinct adaptations. The most striking feature of the aye-aye is perhaps its exceptional near-field auditory system adopted to support its unique tap-scanning process. This tap-scanning technique represents prominent evolutionary innovations in the animal’s biological auditory system. The current study provides an initial insight into proposing a biomimetic approach to determine how different morphological features might impact the ayeaye’s acoustic near-field auditory system. The experimental setup comprised a miniature piezoelectric hammer mounted on a Universal Robotics manipulator (UR5) (the integrated system provides a controlled tapping process) and a prepolarized capacitive measurement microphone (to capture the acoustic sound coming from each tap on the wooden sample). The pinnae of the aye-aye were 3D printed using a CT scan obtained from a carcass. The results show that the biomimetic setup can successfully be used for evaluating the near-field auditory system of aye-ayes.

This paper presents the design and realization of a bioinspired snake robot that can move on the water surface. This robot mimics the locomotion strategies of anguilliform fishes such as eels and lampreys, which have a thin, long, cylindrical body and whose movement resembles the crawling of a snake. An autonomous underwater vehicle with such a shape can pass through narrow crevices and reach places inaccessible to other swimming robots. Moreover, this locomotion entails a high energy efficiency and outstanding agility in maneuvers. The body of the bioinspired robot consists of a modular structure in which each module contains a battery, the electronic board, and a servo motor that drives the following module. The head of the robot has a different shape as it contains a camera and an ultrasonic sensor used to detect obstacles. In addition to the design of the robot, this paper also describes the implementation of the kinematic model.

The use of electricity is so pervasive that life without it is unimaginable today. The scope of electricity is even widening to encompass wearables and draperies in domestic and professional surroundings. The typical way of conducting electricity is through metallic wires and conduits, which often are integrated permanently into engineered products. This means that we have more and more products with mixed materials that are difficult to recycle, thereby creating a major bottleneck towards the achievement of sustainable urban and rural environments. If electricity could be conducted in another way, new design options would become possible. The bioworld offers ways for conducting electricity without metallic interconnects. Examples range from electric discharges by electric eels to electrolocation by fish to bacterial protein networks that conduct electrons. A review of electrical conduction mechanisms in the bioworld suugests the feasibility of incorporating the underlying bioworld principles in engineered products.

Comparable to annual rings present in a tree trunk, human tooth cementum contains yearly deposited incremental layers often termed incremental lines, which are generally visualized from tooth slides with optical microscopy in two dimensions. These micrometer-thin incremental lines are used to decode age-at-death and stress periods over the lifetime of an individuum. One can also visualize these layers without physical slicing by means of hard X rays because of density modulations. Within this project, two optically almost transparent tooth slides were used to record optical data in two dimensions with submicron pixel sizes. These data were registered with projections of available synchrotron radiation-based tomography data of the slides. Such data were also acquired for an entire tooth to determine thickness variations in each layer, the intra-layer thickness, and variations between the layers, the inter-layer thickness, automatically.

Sea cucumbers, marine animals members of the Echinoderms family, will react to an external stimulus by rapidly and reversibly increasing their skin stiffness in order to protect themselves [1-3]. This mechanism has been the source of inspiration for the development of a protective smart layer able to improve the impact resistance of Carbon Fibre Reinforced Polymer (CFRP) laminates. By exploiting a dynamic and autonomous phase transition, this novel, non-Newtonian medium acts as a protective layer on the surface of a laminate by changing its mechanical properties in response to an external stimulus, preventing impact damage such as delamination and microcracks. Low Velocity Impact (LVI) tests were employed at an energetic level of 15 J, to assess the energy absorption characteristics of the protective multi-layered coatings which were compared to an uncoated CFRP laminate. Results from LVI indicated that the proposed smart layers are able to modify the way the energy is distributed during the impact event, due to a dynamic transition between a viscous and rubbery phase of the embedded non-Newtonian material. These data were further confirmed by ultrasonic C-Scan analyses which showed an average reduction of 60% of the extent of the internal damage in comparison with the CFRPs laminates. These results demonstrate that the proposed medium possess unique energy absorption characteristics, thus providing an innovative solution for the protection of CFRP laminates in primary load-bearing applications where they might be subjected to out-of-plane impacts, such as in aerospace or railways components.

Programmable shape memory left atrial appendage (LAA) occlusion devices were explored to address the problem of wear, perforation, and other serious complications associated with Nitinol-based LAA occluders. The developed LAA devices were designed based on the optimized biomimetic network. LAA devices were manufactured by 4D printing, which endowed them with customized and transformable configurations. The LAA device exhibited outstanding durable mechanical performance and favorable biocompatibility. Besides, the shape recovery process verified that the dynamic and controllable 4D transformation of the LAA device was accessible. The LAA device can be deployed in swine heart, which showed the developed LAA device was feasible for LAA occlusion.

In this paper, a squid-like jet propeller actuated by piezoelectric pumps is designed, which can realize underwater pulsedjet process. The squid-like jet propeller comprises a bionic mantle and a rigid framework. The bionic mantle is a sealedflexible cavity, and a plurality of piezoelectric pumps are embedded on the bionic mantle to continuously absorbwaterinto the cavity. When the piezoelectric pump works, water is sucked into the flexible cavity, when the pressure inthecavity reaches a certain value, the jet is ejected through the nozzle. Firstly, this paper studies the structural designof thebionic mantle, then studies the influence of the number and the water absorption performance of piezoelectric pumpsaswell as water absorption time on the propulsion performance of the squid-like jet propeller, and then studies thestructural deformation of the bionic mantle and the variation of the parameters of the jet propeller during the pulsedjet process. The squid-like jet propeller can control the pulsed jet cycle and other propulsion performance.

This paper presents the design and construction of a biomimetic swimming robot inspired by the locomotion of rays. These fishes move by flapping their pectoral fins and creating a wave that moves in the opposite direction to the direction of motion, pushing the water back and giving the fish a propulsive force due to momentum conservation. The robot’s fins are molded from silicone rubber and moved by a servo motor that drives a mechanism inside the leading edge of each fin. The traveling wave, mimicking the movement of the fin, is passively generated by the flexibility of the rubber itself. The robot is also equipped with a tail that acts as a rudder, helpful in performing maneuvers. The rigid central body of the robot is the housing for motors, electronics, and batteries.