This PDF file contains the front matter associated with SPIE Proceedings Volume 9055, including the Title Page, Copyright information, Table of Contents, Invited Panel Discussion, and Conference Committee listing.

Research in the fields of biomimetic and biohybrid systems is developing at an accelerating rate. Biomimetics can be understood as the development of new technologies using principles abstracted from the study of biological systems, however, biomimetics can also be viewed from an alternate perspective as an important methodology for improving our understanding of the world we live in and of ourselves as biological organisms. A biohybrid entity comprises at least one artificial (engineered) component combined with a biological one. With technologies such as microscale mobile computing, prosthetics and implants, humankind is moving towards a more biohybrid future in which biomimetics helps us to engineer biocompatible technologies. This paper reviews recent progress in the development of biomimetic and biohybrid systems focusing particularly on technologies that emulate living organisms—living machines. Based on our recent bibliographic analysis [1] we examine how biomimetics is already creating life-like robots and identify some key unresolved challenges that constitute bottlenecks for the field. Drawing on our recent research in biomimetic mammalian robots, including humanoids, we review the future prospects for such machines and consider some of their likely impacts on society, including the existential risk of creating artifacts with significant autonomy that could come to match or exceed humankind in intelligence. We conclude that living machines are more likely to be a benefit than a threat but that we should also ensure that progress in biomimetics and biohybrid systems is made with broad societal consent.

How did we get to the point where we don’t have time to be inspired by the wonders of Nature? Our office walls, homes and city streets are so plain that even when we do escape to a retreat with nature all around us, we may be blind to its magnificence. Yet there are many who have applied what can be known of natural systems (NS) to create practical solutions, but often definite applications for them are lacking. Mimicry of natural systems is not only more possible than ever before, but the education and research programs in many major universities are churning out graduates with a real appreciation for Nature’s complex integrated systems. What if these skills and perspectives were employed in the teams of systems engineers and the technology developers that support them to help the teams think “outside-the-box” of manmade inventions? If systems engineers (SE) and technology developers regularly asked the question, “what can we learn from Nature that will help us?” as a part of their processes, they would discover another set of potential solutions. Biomimicry and knowledge of natural systems is exploding. What does this mean for systems engineering and technology? Some disciplines such as robotics and medical devices must consider nature constantly. Perhaps it’s time for all technology developers and systems engineers to perceive natural systems experts as potential providers of the technologies they need.

Insects are the most diverse natural flyers in nature, being able to hover and perform agile manoeuvres. Dragon- flies in particular are aggressive flyers, attaining accelerations of up to 4g. Flight in all insects requires demanding aerodynamic and inertial loads be overcome. It has been proposed that resonance is a primary mechanism for reducing energy costs associated with flapping flight, by storing energy in an elastic thorax and releasing it on the following half-stroke. Certainly in insect flight motors dominated by inertial loads, such a mechanism would be extremely beneficial. However in highly manoeuvrable, aerodynamically dominated flyers, such as the dragonfly, the use of elastic storage members requires further investigation. We show that employing resonant mechanisms in a real world configuration produces minimal energy savings that are further reduced by 50 to 133% across the operational flapping frequency band of the dragonfly. Using a simple harmonic oscillator analysis to represent the dynamics of a dragonfly, we further demonstrate a reduction in manoeuvring limits of ∼1.5 times for a system employing elastic mechanisms. This is in contrast to the potential power reductions of √2/2 from regulating aerodynamics via active wing articulation. Aerodynamic means of energy storage provides flexibility between an energy efficient hover state and a manoeuvrable state capable of large accelerations. We conclude that active wing articulation is preferable to resonance for aerodynamically dominated natural flyers.

The emerald ash borer (EAB), Agrilus planipennis, is an invasive tree-killing pest in North America. Like other buprestid beetles, it has an iridescent coloring, produced by a periodically layered cuticle whose reflectance peaks at 540 nm wavelength. The males perform a visually mediated ritualistic mating flight directly onto females poised on sunlit leaves. We attempted to evoke this behavior using artificial visual decoys of three types. To fabricate decoys of the first type, a polymer sheet coated with a Bragg-stack reflector was loosely stamped by a bioreplicating die. For decoys of the second type, a polymer sheet coated with a Bragg-stack reflector was heavily stamped by the same die and then painted green. Every decoy of these two types had an underlying black absorber layer. Decoys of the third type were produced by a rapid prototyping machine and painted green. Fine-scale features were absent on the third type. Experiments were performed in an American ash forest infested with EAB, and a European oak forest home to a similar pest, the two-spotted oak borer (TSOB), Agrilus biguttatus. When pinned to leaves, dead EAB females, dead TSOB females, and bioreplicated decoys of both types often evoked the complete ritualized flight behavior. Males also initiated approaches to the rapidly prototyped decoy, but would divert elsewhere without making contact. The attraction of the bioreplicated decoys was also demonstrated by providing a high dc voltage across the decoys that stunned and killed approaching beetles. Thus, true bioreplication with fine-scale features is necessary to fully evoke ritualized visual responses in insects, and provides an opportunity for developing insecttrapping technologies.

Stochastic threshold devices using trap-filling transition coupled with molecular dynamics in poly(3-alkyl thiophene)s [P3ATs] were fabricated as potential key devices for noise-driven bio-inspired sensors and infor- mation processors. This article deals with variable-temperature direct current conductivity and alternating current impedance measurements for vertical-type device elements of Au/regioregular poly(3-decylthiophene) [RR-P3DT] (thickness:100nm)/Au, which show multiple conducting states and quasi-stochastic transitions between these states. Noise measurements indicate the ω^-2-type (if V < V_TFT = 10V) and ω^-1-type (if V > V_TFT) power spectral densities, where V and V_TFT are an applied voltage and the voltage for trap-filling transition(TFT),respectively. The noise generation is due to TFT that associated with twist dynamics of π-conjugated polymers near the order-disorder phase transition. At 298K, the quasi-stochastic behavior is more noticeable for RR-P3DT than poly(3-hexylthiophene) [RR-P3HT]. The dynamics of the order-disorder phase transition (ODT) for powder samples were also investigated by differential scanning calorimetry (DSC) measurements and high-resolution solid-state C NMR spectroscopy, and the correlation of molecular structure and dynamics with electric properties was discussed.

Reducing the environmental impact of aviation is a primary goal of NASA aeronautics research. One approach to achieve this goal is to build lighter weight aircraft, which presents complex challenges due to a corresponding increase in structural flexibility. Wing flexibility can adversely affect aircraft performance from the perspective of aerodynamic efficiency and safety. Knowledge of the wing position during flight can aid active control methods designed to mitigate problems due to increased wing flexibility. Current approaches to measuring wing deflection, including strain measurement devices, accelerometers, or GPS solutions, and new technologies such as fiber optic strain sensors, have limitations for their practical application to flexible aircraft control. Hence, it was proposed to use a bio-mimetic optical sensor based on the fly-eye to track wing deflection in real-time. The fly-eye sensor has several advantages over conventional sensors used for this application, including light weight, low power requirements, fast computation, and a small form factor. This paper reports on the fly-eye sensor development and its application to real-time wing deflection measurement.

The compound eye of the insect in its simplest concept creates an image from the environment over a solid angle, yet in practice angular resolution varies significantly across most compound eyes. We have examined the case of linear optical (paraxial) arrays in which optical axes are parallel. We demonstrate that a paraxial array directly measures the speed of translation orthogonal to the optical axes, while when rotated, it detects range as a ratio of optical flow and angular velocity. A series of experiments was conducted to demonstrate the viability of the device.

In this study we present the design, analysis, and experimental validation of a tunable follicle-sinus complex (FSC) unit for whisker-like sensors. The tunable FSC unit displays variable viscoelasticity enabled by a dielectric elastomer (DE) mechanism. Our previous studies on whisker-like sensors for underwater applications have shown the dependence between both static and dynamic sensor performance and FSC material properties. Variations in FSC modulus and viscosity affect its effective stiffness and damping and in turn the sensitivity and range of the sensors. A new FSC design is presented that uses a DE mechanism to tune the effective stiffness and damping of the follicle region. A model to better predict the resulting sensitivity and measurement range is described. The model accounts for the viscoelastic of the FSC components, pre-loading of the FSK volume, and stiffness ratios between the sensor whisker-like shaft and the FSC region. The changes in both the stiffness and damping of the whisker-like sensors are characterized experimentally using loading and impulse tests and compared with model estimates.

Recently, a bio-inspired, synthetic membrane-based hair cell sensor was fabricated and characterized. This sensor generates current in response to mechanical stimuli, such as airflow or free vibration, which perturb the sensor’s hair. Vibration transferred from the hair to a lipid membrane (lipid bilayer) causes a voltage-dependent time rate of change in electrical capacitance of the membrane, which produces measurable current. Studies to date have been performed on systems containing only two droplets and a single bilayer, even though an array of multiple bilayers can be formed with more than 2 droplets. Thus, it is yet to be determined how multiple lipid bilayers affect the sensing response of a membrane-based hair cell sensor. In this work, we assemble serial droplet arrays with more than 1 bilayer to experimentally study the current generated by each membrane in response to perturbation of a single hair element. Two serial array configurations are studied: The first consists of a serial array of 3 bilayers formed using 4 droplets with the hair positioned in an end droplet. The second configuration consists of 3 droplets and 2 bilayers in series with the hair positioned in the central droplet. In serial arrays of up to four droplets, we observe that mechanotransduction of the hair’s motion into a capacitive current occurs at every membrane, with bilayers positioned adjacent to the droplet containing the hair generating the largest sensing current. The measured currents suggest the total current generated by all bilayers in a 4-droplet, 3-bilaye array is greater than the current produced by a single-membrane sensor and similar in magnitude to the sum of currents output by 3, single-bilayer sensors operated independently. Moreover, we learned that bilayers positioned on the same side of the hair produce sensing currents that are in-phase, whereas bilayers positioned on opposite sides of the droplet containing the hair generate out-of-phase responses.

We draw inspiration from the fish “hearing” organ, the otolith, to create a portable engineering device that can augment a human diver’s ability to hear underwater. The otolith is an inertial displacement sensor, consisting of a dense bony mass that acts as a reference to the surrounding sensory hair cells. The challenges in adapting the otolith into a hearing device are discussed. For our proposed sensor, we have explored the use of capacitive sensing for measuring displacement. A proof of concept prototype and a finite element model of the sensor are presented.

Self-organisation appeals to humans because difficult and repeated actions can be avoided through automation via bottom-up nonhierarchical processes. This is in contrast to the top-level controlled action strategy normally applied in automated products and in manufacturing. There are many situations where it is required that objects perform an action dependent on external stimuli. An example is automatic window blinds that open or closes in response to sunlight level. However, simpler and more robust designs could be made using the self-organising principles for movement found in many plants. Plants move to adapt to external conditions, e.g. sun-flower buds tracking the sun, touch-me-not Mimosa and Venus fly trap responding to mechanical stimuli by closing leaves to protect them and capture insects respectively. This paper describes 3 of the basic biomimetic principles used by plants to track the sun; i) light causing an inhibiting effect on the illuminated side causing it to bend, ii) light inducing a signal from the illuminated side that causes an action on the darker side and iii) light illuminating a number of sensing plates pointing upwards at an angle activate an expansion on the same side. A concept for mimicking the second principle is presented. It is a very simple and possible reliable self-organising structure that aligns a plate perpendicular to the source of illumination.

Biomimetics faces a continual challenge of how to bridge the gap between what Nature has so effectively evolved and the current tools and materials that engineers and scientists can exploit. Kirigami, from the Japanese ‘cut’ and ‘paper’, is a method of design where laminar materials are cut and then forced out-of-plane to yield 3D structures. Kirimimetic design provides a convenient and relatively closed design space within which to replicate some of the most interesting niche biological mechanisms. These include complex flexing organelles such as cilia in algae, energy storage and buckled structures in plants, and organic appendages that actuate out-of-plane such as the myoneme of the Vorticella protozoa. Where traditional kirigami employs passive materials which must be forced to transition to higher dimensions, we can exploit planar smart actuators and artificial muscles to create self-actuating kirigami structures. Here we review biomimetics with respect to the kirigami design and fabrication methods and examine how smart materials, including electroactive polymers and shape memory polymers, can be used to realise effective biomimetic components for robotic, deployable structures and engineering systems. One-way actuation, for example using shape memory polymers, can yield complete self-deploying structures. Bi-directional actuation, in contrast, can be exploited to mimic fundamental biological mechanisms such as thrust generation and fluid control. We present recent examples of kirigami robotic mechanisms and actuators and discuss planar fabrication methods, including rapid prototyping and 3D printing, and how current technologies, and their limitations, affect Kirigami robotics.

This paper reports the experimental progress towards developing a multi-segment in-pipe robot inspired by earthworm’s body structure and locomotion mechanism. To mimic the alternating contraction and elongation of a single earthworm’s segment, a robust, servomotor based actuation mechanism is developed. In each robot segment, servomotor-driven cords and spring steel belts are utilized to imitate the earthworm’s longitudinal and circular muscles, respectively. It is shown that the designed segment can contract and relax just like an earthworm’s body segment. The axial and radial deformation of a single segment is measured experimentally, which agrees with the theoretical predictions. Then a multisegment earthworm-like robot is fabricated by assembling eight identical segments in series. The locomotion performance of this robot prototype is then extensively tested in order to investigate the correlation between gait design and dynamic locomotion characteristics. Based on the principle of retrograde peristalsis wave, a gait generator is developed for the multi-segment earthworm-like robot, following which gaits of the robot can be constructed. Employing the generated gaits, the 8-segment earthworm-like robot can successfully perform both horizontal locomotion and vertical climb in pipes. By changing gait parameters, i.e., with different gaits, locomotion characteristics including average speed and anchor slippage can be significantly tailored. The proposed actuation method and prototype of the multi-segment in-pipe robot as well as the gait generator provide a bionic realization of earthworm’s locomotion with promising potentials in various applications such as pipeline inspection and cleaning.

We explore fish-robot interactions in a comprehensive set of experiments designed to highlight the effects of speed and configuration of bioinspired robots on live zebrafish. The robot design and movement is inspired by salient features of attraction in zebrafish and includes enhanced coloration, aspect ratio of a fertile female, and carangiform/subcarangiformlocomotion. The robots are autonomously controlled to swim in circular trajectories in the presence of live fish. Our results indicate that robot configuration significantly affects both the fish distance to the robots and the time spent near them.

A novel hair flow sensor is designed inspired by the superficial neuromasts in the lateral line system of fish. The transduction element of the hair sensor is a piezoelectric fiber with a pair of electrodes on the surface of the fiber. An innovative approach is proposed to adapt the frequency response of the sensor, by connecting the sensor to a shunt circuit. The effect of the circuit components (resistor and inductor) is studied by solving the fully coupled mechanoelectrical- circuit system.

Nature has often provided inspiration for new smart structures and materials. Recently, we showed a bundle of a few wood cells are moisture-activated torsional actuators that can reversibly twist multiple revolutions per centimeter of length. The bundles produce specific torque higher than that produced by electric motors and possess shape memory twist capabilities. Here we also report that ion diffusion through wood cell walls is a stimuli-responsive phenomenon. Using the high spatial resolution and sensitivity of synchrotron-based x-ray fluorescence microscopy (XFM), metal ions deposited into individual wood cell walls were mapped. Then, using a custom-built relative humidity (RH) chamber, diffusion of the metal ions was observed in situ first at low RH and then at increasingly higher RH. We found that ions did not diffuse through wood cell walls at low RH, but diffusion occurred at high RH. We propose that both the shape memory twist effect and the moisture content threshold for ionic diffusion are controlled by the hemicelluloses passing through a moisture-dependent glass transition in the 60-80% RH range at room temperature. An advantage of wood over other stimuli-responsive polymers is that wood lacks bulk mechanical softening at the transition that controls the stimuliresponsive behavior. We demonstrate using a custom-built torque sensor that the torque generation in wood cell bundles actually continues to increase over the RH range that hemicelluloses soften. The hierarchical structure of wood provides the inspiration to engineer stimuli-responsive polymers and actuators with increased mechanical strength and higher recovery stresses.

Joining composites with metal parts leads, inevitably, to high stress concentrations because of the material property mismatch. Since joining composite to metal is required in many high performance structures, there is a need to develop a new multifunctional approach to meet this challenge. This paper uses the biomimetics approach to help develop solutions to this problem. Nature has found many ingenious ways of joining dissimilar materials and making robust attachments, alleviating potential stress concentrations. A literature survey of natural joint systems has been carried out, identifying and analysing different natural joint methods from a mechanical perspective. A taxonomy table was developed based on the different methods/functions that nature successfully uses to attach dissimilar tissues (materials). This table is used to understand common themes or approaches used in nature for different joint configurations and functionalities. One of the key characteristics that nature uses to joint dissimilar materials is a transitional zone of stiffness in the insertion site. Several biomimetic-inspired metal-to-composite (steel-to-CFRP), adhesively bonded, Single Lap Joints (SLJs) were numerically investigated using a finite element analysis. The proposed solutions offer a transitional zone of stiffness of one joint part to reduce the material stiffness mismatch at the joint. An optimisation procedure was used to identify the variation in material stiffness which minimises potential failure of the joint. It was found that the proposed biomimetic SLJs reduce the asymmetry of the stress distribution along the adhesive area.

Magnet filler–polymer matrix composites (Magpol) are an emerging class of morphing materials. Magpol composites have an interesting ability to undergo large strains in response to an external magnetic field. The potential to develop Magpol as large strain actuators is due to the ability to incorporate large particle loading into the composite and also due to the increased interaction area at the interface of the nanoparticles and the composite. Mn-Zn ferrite fillers with different saturation magnetizations (Ms) were synthesized. Magpol composites consisting of magnetic ferrite filler particles in an Poly ethylene vinyl acetate (EVA) matrix were prepared. The deformation characteristics of the actuator were determined. The morphing ability of the Magpol composite was studied under different magnetic fields and also with different filler loadings. All films exhibited large strain under the applied magnetic field. The maximum strain of the composite showed an exponential dependence on the Ms. The work output of Magpol was also calculated using the work loop method. Work densities of upto 1 kJ/m³ were obtained which can be compared to polypyrrole actuators, but with almost double the typical strain. Applications of Magpol can include artificial muscles, drug delivery, adaptive optics and self healing structures. Advantages of Magpol include remote contactless actuation, high actuation strain and strain rate and quick response.

Autonomous bimodal microsystems exhibiting survivability behaviors and characteristics are able to adapt dynamically in any given environment. Equipped with a background blending exoskeleton it will have the capability to stealthily detect and observe a self-chosen viewing area while exercising some measurable form of selfpreservation by either flying or crawling away from a potential adversary. The robotic agent in this capacity activates a walk-fly algorithm, which uses a built in multi-sensor processing and navigation subsystem or algorithm for visual guidance and best walk-fly path trajectory to evade capture or annihilation. The research detailed in this paper describes the theoretical walk-fly algorithm, which broadens the scope of spatial and temporal learning, locomotion, and navigational performances based on optical flow signals necessary for flight dynamics and walking stabilities. By observing a fly’s travel and avoidance behaviors; and, understanding the reverse bioengineering research efforts of others, we were able to conceptualize an algorithm, which works in conjunction with decisionmaking functions, sensory processing, and sensorimotor integration. Our findings suggest that this highly complex decentralized algorithm promotes inflight or terrain travel mobile stability which is highly suitable for nonaggressive micro platforms supporting search and rescue (SAR), and chemical and explosive detection (CED) purposes; a necessity in turbulent, non-violent structured or unstructured environments.

The propulsive performance of flexible flapping fins greatly depends on the stiffness of the fins along with the oscillating parameters. The bending mode shape and trailing edge deflection of the oscillating fins play a major role in the generation of thrust and efficiency. This paper examines the deformation pattern of heaving flexible foils and its dependency on propulsive performance. Experimental investigation has been carried out on fins of various lengths oscillating at their leading edge. A LaVision 2D/3D StrainMaster Digital Image Correlation (DIC) system was used to measure the deformation of the fins. It is observed that the propulsive performance can be maximized by operating at frequencies close to resonance. Trailing edge amplitude and deformation pattern together play an important role in achieving high propulsive performance even when the oscillation frequency is not close to resonant frequency.

The world of insects displays myriad hues of coloration effects produced by elaborate nano-scale architectures built into wings and exoskeleton. For example, we have recently found many weevils possess photonic architectures with cubic lattices. In this talk, we will present high-resolution three-dimensional reconstructions of weevil photonic structures with diamond and gyroid lattices. Moreover, by reconstructing entire scales we found arrays of single-crystalline domains, each oriented such that only selected crystal faces are visible to an observer. This pixel-like arrangement is key to the angle-independent coloration typical of weevils—a strategy that could enable a new generation of coating technologies.

Inspired by the apposition compound eyes of some dipterans, we analyzed the effect of texturing the exposed face of a silicon solar cell by ray-tracing simulation. Bioinspired textures of two types were considered: hillock textures and pit textures. A multifrequency analysis-that took into account the broadband nature of solar radiation and its amplitude at the sea-level, as well as the wavelength dependence of the complex-valued refractive index of silicon-showed that both types of bioinspired textures are beneficial. We found that the light-coupling efficiency can be enhanced by as much as 20% and 24% with respect to that of a flat surface when the exposed face of a silicon solar cell is decorated with the bioinspired hillock texture and the bioinspired pit texture, respectively.

In the last decade, many researchers pursued the development of tiny flying robots inspired by natural flyers destined for the exploration of confined spaces, for example. Within this context, our main objective is to devise a flying robot bioinspired from insect in terms of size and wing kinematics using MEMS technologies. For this purpose, an original design has been developed around resonant thorax and wings by the way of an indirect actuation and a concise transmission whereas the all-polymer prototypes are obtained using a micromachining SU-8 photoresist process. This paper reports our recent progress on the design of a flapping-wing robotic insect as well as on the characterization of its performance. Prototypes with a wingspan of 3 cm and a mass of 22 mg are achieved. Due to the introduction of an innovative compliant link, large and symmetrical bending angles of 70° are obtained at a flapping frequency of 30 Hz along with passive wing torsion while minimizing its energy expenditure. Furthermore, it leads to a mean lift force representing up to 75 % of the prototype weight as measured by an in-house force sensor. Different improvements are currently underway to increase the power-to-weight ratio of the prototype and to obtain an airborne prototype.

The increased use of Unmanned Aerial Vehicles (UAVs) has created a continuous demand for improved flight capabilities and range of use. During the last decade, engineers have turned to bio-inspiration for new and innovative flow control methods for gust alleviation, maneuverability, and stability improvement using morphing aircraft wings. The bio-inspired wing design considered in this study mimics the flow manipulation techniques performed by birds to extend the operating envelope of UAVs through the installation of an array of feather-like panels across the airfoil’s upper and lower surfaces while replacing the trailing edge flap. Each flap has the ability to deflect into both the airfoil and the inbound airflow using hinge points with a single degree-of-freedom, situated at 20%, 40%, 60% and 80% of the chord. The installation of the surface flaps offers configurations that enable advantageous maneuvers while alleviating gust disturbances. Due to the number of possible permutations available for the flap configurations, an iterative constant-strength doublet/source panel method has been developed with an integrated boundary layer model to calculate the pressure distribution and viscous drag over the wing’s surface. As a result, the lift, drag and moment coefficients for each airfoil configuration can be calculated. The flight coefficients of this numerical method are validated using experimental data from a low speed suction wind tunnel operating at a Reynolds Number 300,000. This method enables the aerodynamic assessment of a morphing wing profile to be performed accurately and efficiently in comparison to Computational Fluid Dynamics methods and experiments as discussed herein.

Noncontact sensing techniques is gaining prominence for structural health monitoring (SHM) and nondestructive testing (NDT) due to (1) their noncontact and nonintrusive natures, (2) their spatial resolution much higher than conventional discrete sensors can achieve, (3) their less dependency on baseline data obtained from the pristine condition of a target structure (reference-free diagnosis), (4) cost and labor reduction in sensor installation and maintenance. In this talk, a suite of noncontact sensing techniques particularly based on laser technology will be presented for SHM and NDT of aircraft, wind turbine blades, high-speed trains, nuclear power plants, bridges, automobile manufacturing facilities and semiconductors.

Nanowires represent excellent building blocks for future nanoelectronics, due to their efficient charge transport characteristics. Here we present light-induced switching behaviour of porphyrin-coated silicon nanowire field effect transistors (Si NW FETs) and demonstrate their capabilities for design of hybrid nanodevices – consisting of organic complexes and inorganic nanowires. Switching of Si NW FETs highly reflects the electrical change of porphyrin molecules by light. To demonstrate significant factors of concentration-dependent switching of porphyrin-covered devices, electrical charging mechanism through molecules and nanowires has been understood, that allows the systematic integration of the hybrid devices.

There is a gradual shift in emphasis from periodic inspection with detachable transducers (NDT) to permanently installed monitoring systems giving information about the structural integrity at pre-programmed intervals or on demand (SHM). The drivers of this change are discussed, together with the requirements of successful SHM systems. Particular issues are that NDT often involves scanning and this is not possible with typical SHM configurations; it therefore becomes important to cover a significant area of structure from each transducer position. Guided waves provide a possible solution to this problem and permanently installed guided wave pipe inspection systems are now available. The sensitivity obtained with a permanently installed system is significantly better than that in a one-off test as baseline subtraction can be employed. However, this is far from trivial as it is necessary to compensate for benign changes such as temperature. The guided wave technique does not provide accurate remaining thickness information and is best complemented by point measurements at selected locations. Another issue is that the SHM transducers must survive in operational conditions, which is particularly difficult at high temperatures. Recent work at Imperial College and associated spin-out companies on solutions to these problems is discussed.

Euglenoids are unicellular aquatic organisms. These microalgae show a typical surface structure that distinguishes them from the other protists. Most cells are naked and bounded by a plasma membrane surrounded by a pellicle formed by overlapping bands. It is well known that all terrestrial and aquatic organisms are exposed to UV-A and UV-B radiation. This radiation is potentially harmful to life and since it can penetrate up to 12 meters in the water, it can reduce survival, growth and production of phytoplankton. However, the organisms have developed numerous protection mechanisms intended to reduce such damage, such as the production of pigments and other repair mechanisms. However, the possible protection that could provide the first barriers before entering into the cell has not been explored yet. In this paper we investigate, from an electromagnetic point of view, the role played by the pellicle of euglenoids in the protection of the cell against UV radiation. To do so, we investigate the electromagnetic response of different species that exhibit different behaviors against the UV radiation. We solve the diffraction problem by using the Chandezon Method and obtain the reflectance of the pellicle for the UV wavelengths. The results show that the corrugated pellicle could contribute to increase the reflectance, thus reducing the penetration of the UV radiation within the cell and therefore, minimizing the damage and increasing the survival of these organisms.

Metal oxides such as titanium dioxide and zink oxide are well-known semiconductors. They are used in various a wide variety of functional devices. The size and morphology of the material has a substantial effect on device performance. Here, we propose to manufacture a hierarchic assembly of nanomaterials on the micrometer scale to arrive at new functionalities for photonic devices. The construction of the materials follows a bottom-up assembly that mimics processes that occur in nature.

The sensory means by which hover is achieved could be inertial, visual or an unexplained sensory modality. Dragonflies in their natural habitat were shown not to maintain a stationary position in wind. Their position fluctuated significantly while returning to the original position. The movement of the dragonfly is correlated with the movement of vertically standing vegetation. This response would be non-causal with wind for an inertial or putative pressure based internal sensory system. It is postulated that with a substrate of moving water, sensitivity to movement on the visual horizon for controlling hover is a robust strategy.

Insect wings consist of flat plates of membranes stiffened by spars. The effect of this structure is that the wings appear as corrugated surfaces when considered on chordwise sections. We know that aerodynamically efficient insects such as a dragonfly engage in fixed wing flight modes for extended periods. The analysis in the literature has shown that the aerodynamic efficiency (c_l/c_d) of a corrugated aerofoil is sensitive to Reynolds number (Re) and angle-of-attack (AoA), yet the conclusions established are on the basis of flow analysis on a single baseline shape only. The sample size of the aerofoils must be extended further so that the influence and merits of corrugated shape features can be established. In this work, a design-of-experiments (DoE) approach is applied to induce systematic shape perturbations on a select, off-the-shelf baseline shape one feature at a time over a set number of increments. At each shape increment, the aerodynamic forces are established using a high fidelity CFD solver. The design space is modeled at a Re of 20,000 and 34,000 and at flow angle of 4.0° to represent a Micro Air Vehicle (MAV) in glide. The results confirmed the importance of the leading and trailing edge deflections on cl/cd. At Re = 20, 000, c_l/c_d of a corrugated aerofoil with deflection at the leading edge region only is 16% higher than the baseline shape, and 39% higher than the flat plate. At Re = 34, 000, c_l/c_d performance is sensitive to the trailing edge deflection. At the optimum deflection setting, c_l/c_d is 18% higher than the baseline shape and 23% higher than the flat plate. The results confirm that the leading and trailing edge deflections are critical to c_l/c_d for a MAV in glide.