This PDF file contains the front matter associated with SPIE Proceedings Volume 8686, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

This talk presents a review of bioinspiration in textiles, and how biomimicry can lead to fibrous materials with specialized properties. After an abbreviated introduction to textiles, we focus on the fiber, as the elemental building block of textiles. The discussion centers on how biology has and will inform fiber engineering and science.

Hydraulic control systems are a known power dense form of actuation for large scale systems such as excavators, aircraft, and agricultural equipment. Fluid power at the meso-scale is much rarer since electromechanical actuation is usually sufficient for the application. However, the application at hand is a humanoid, lower extremity, bipedal robot, and with the required forces, electromechanical actuation would result in bulky actuators at the joints. Since not much has been done on this size, and scaling effects are not intuitive, it was not obvious what system pressures should be used to ensure the hydraulic control’s power density was taken advantage of. A study of the effects of operating pressure on system weight is presented herein. The results indicate there is indeed an optimal operating pressure in terms of overall weight.

Pneumatic artificial muscles (PAMs) are actuators known for their light weight, high specific force, and natural compliance. Employed in antagonistic schemes, these actuators closely mimic biological muscle pairs, which has led to their use in humanoid and other bio-inspired robotics applications. Such systems require precise actuator modeling and control in order to achieve high performance. In the present study, refinements are introduced to an existing model of pneumatic artificial muscle force-contraction behavior. The force balance modeling approach is modified to include the effects of non-constant bladder thickness and up to a fourth-order polynomial stress-strain relationship is adopted in order to more accurately capture nonlinear PAM force behavior in both contraction and extension. Moreover, the polynomial coefficients of the stress-strain relationship are constrained to vary linearly with pressure, improving the ability to predict behavior at untested pressure levels while preserving model accuracy at tested pressure levels. Additionally, a detailed geometric model is applied to improve force predictions, particularly during PAM extension. By modeling bladder end effects as sections of an elliptic toroid, PAM force predictions as a function of strain are improved. These modeling improvements combine to enable enhanced model-based control in PAM actuator applications.

This paper presents experimental data on the actuation properties of McKibben muscles constructed with varying bladder pre-strain and thickness. The tests determine quasi-static force-length relationships during extension and contraction, for muscles constructed with unstretched bladder lengths 50%, 67%, and 100% of the stretched muscle length, as well as two different wall thicknesses of the rubber. Existing models do not adequately describe the effects of these variations, making it difficult to determine the best geometry for an application. The quasi-static actuator force and maximum contraction length are found to depend strongly on the thickness and modulus of the rubber, as well as the amount of pre-strain. A model is presented to better predict force-length characteristics from geometric parameters. It accounts for the nonlinear elastic properties of the bladder as well as friction. It includes axial force generated by stretching the bladder during construction, and it also describes the hoop stress created by radial expansion of the bladder, which partially counteracts the internal fluid pressure that presses outward on the mesh, thus reducing both axial force and friction between the mesh and bladder. The hyperelastic rubber bladder is modeled as a Mooney-Rivlin incompressible solid. The axial force generated by the mesh is found directly from contact forces rather than from potential energy. The model closely matches the experimental data on wall thickness, while the effects of bladder pre-stretching are not fully explained. A thick-walled bladder model is shown to improve the fit.

In this study, we investigate the interactions between individual Golden shiners (Notemigonus crysoleucas) and robotic fish swimming together in a water tunnel at constant flow velocity. The robotic fish is designed to mimic its live counterpart in the aspect ratio, body shape, dimension, and locomotory pattern. Fish behavioral response is experimentally analyzed as the robot’s tail-beat frequency is varied and particle image velocimetry is utilized to investigate the flow structure behind the robotic fish. Experimental results show that the attraction of Golden shiners for the robotic fish is maximized when the robot beats its tail as the live subjects. In this condition, fish swim at the same depth of the robotic fish, which corresponds to the region of the water tunnel where hydrodynamic return is most likely to be relevant.

This study reports the progress made towards understanding of the low energy propulsion mechanism of medusae (jellyfish) for developing energy efficient unmanned underwater vehicles (UUV). The focus of this investigation is on identifying the techniques required for prolonged sustainability of UUVs. Inspiration is taken from the constant feeding and energy generation achieved by Rhizostomeae. Rhizostomeae, in particular, utilize oral structures comprised of internal channels that capture zooplankton entrained in flow surrounding and in the wake of jellyfish on distal capture surfaces. A passive model was generated for the capture surfaces utilizing the physical dimensions based upon the morphology of Mastigias papua with a bell diameter of 17.2 cm. Geometry and structure of the oral components were derived from literature, live samples, and digitization of video. Based upon this data, a mold was created using silicone and assembled to achieve jellyfish inspired architecture. Geometries used to create the passive model were input into a Finite Element Analysis (FEA) simulation along with the experimental material properties of jellyfish mesoglea to ascertain the affect that the oral structure has on the kinematics and bell stresses. A forcing function was derived to achieve a close approximation of the jellyfish kinematics for the case of a jellyfish bell with oral structure attached. The same forcing function was applied to the singular bell and an increase in the bending was observed. With the escalation in bending came an increased level of principle stress within the bell closer to the margin. From this the stiffness elements that must be compensated with increased actuation force applied to the bell achieving proper swimming kinematics can be identified.

This work investigates the fabrication of hydrogel based lipid bilayers arrays using micro fabrication technologies that enable high precision in controlling the cell-scale droplets. Arrays of hydrogels that support curved aqueous lenses are deposited on two parallel substrates using lithography techniques on top of a network of Ag/AgCl electrodes. The first step in the fabrication process is to deposit silver electrodes using silver paint through a mask, a layer of silver chloride is then formed around the silver channels using another mask with the desired geometry. The hydrogel arrays are then achieved by exposing a thin film of photocrosslinkable hydrogel to UV light through a mask. Hydrogel arrays are fabricated using this technique, which is represents a relatively accurate and inexpensive method. The hydrogel structures can host a thin aqueous curved lenses containing phospholipids . Bilayer arrays can be formed by using a technique similar to the regulated attachment method, where mechanical force is used to bring adjacent aqueous lenses in contact.

The beetle Melanophila acuminata detects forest fires from distances of about 80 miles. For the detection of fires, the beetle uses specialized infrared-sensing receptors. Inspired by this extremely sensitive natural device, we are developing an uncooled IR sensor. The beetle’s IR receptors are based on a fluid-filled pressure cell. By absorbing IR radiation, the fluid heats up and expands. The receptor senses the ensuing pressure increase using a mechanoreceptor. To discriminate between fast but small pressure signals, evoked by a distant heat source and slow but large background signals, due to changes in ambient temperature, the beetle has developed a sophisticated compensation mechanism. Our sensor will feature a size of a few mm² and is fabricated using MEMS technology. The sensor uses the same mechanism as the beetle’s IR receptor, except for pressure sensing. The pressure increase inside the pressure cell deflects a membrane on top of which one electrode of a plate capacitor is located; this evokes changes in capacitance of a few fF (10⁻¹⁵ F). A long and narrow channel connects the pressure cell to a compensation chamber. To the outside, this chamber is sealed by a thin and elastic PDMS membrane. The channel enables the slow transfer of fluid to the compensation chamber while the thin membrane maintains the pressure inside this chamber close to the ambient pressure. Without this mechanism, the pressure inside the capacitor chamber would rise slowly due to ambient temperature changes and finally destroy the sensor.

We report on the first successful development and implementation of an automatic polarisation compass as the primary heading sensor for a UAV. Polarisation compassing is the primary navigation sense of many flying and walking insects, including bees, ants and crickets. Manually operated polarisation astrolabes were fitted in some passenger airliners prior to the implementation of the global positioning system, to compensate for the overal degradation of magnetic and gyrocompass sensors in polar regions. The device we developed demonstrated accurate determination of the direction of the Sun, with repeatability of better than 0.2 degrees. These figures are comparable to any solid state magnetic compass, including flux gate based devices. Flight trials were undertaken in which the output of the polarimeter was the only heading reference used by the aircraft as it flew through GPS waypoints.

The issue of sustainable development in building engineering has been discussed since the early 90’s. The current research seeks to aid in this endeavor by reducing the heating and cooling loads on a building through its envelope, more specifically the wall material. The problem as viewed by most researchers is that the most common building materials, such as concrete and steel, allow for easy heat and mass transfer into buildings. Researchers now look to earth-based materials as passive building materials for increased thermal regulation. The building envelope of earth-based materials is an important buffer for heat and mass transfer into the building environment, but is a part of a bigger picture, which includes hygrothermal loads from the occupants and other facets of the indoor environment, as well as the mechanisms that regulate the indoor environment. This research looks at the soil-based building materials in different light. Our premise is that an understanding of the analogies between thermoregulatory systems in skin, plant, and soils, would inspire us to use soils as intelligent materials in stabilized earth construction with their pore geometries engineered based on these analogies. This biomimetic approach of developing “geodermis” can be broken into two smaller problems: (1) “sensory/nervous systems” to collect and process surrounding hygrothermal data, and (2) “motor system” for semi-active hygrothermal control with the combination of passive regulation by soil and active regulation based on the information from the sensory/nervous system. The Auto Modulating Pattern Detection Algorithm (AMP) is a novel bio-inspired model-free data processing technique that extends the Hilbert-Huang Transform method to detect a “small” but important intermittent event of interest that is usually masked by “dominant” environmental disturbances in various monitoring applications. With AMP, higher detectability can be achieved by: (1) amplifying the amplitude of the pattern-changing event’s frequency characteristics in the time-frequency domain, (2) reducing the baseline frequency fluctuation in the time-frequency domain, and (3) increasing the temporal resolution of the energy-time-frequency domain signal.

Sensory systems found in biology continue to outperform their man-made peers in many respects. In particular, their ability to extract salient information from complex, unstructured environments is often superior to engineering solutions. Bat biosonar is an example for an exceptionally powerful yet highly parsimonious sensing system that is capable of operating in a wide variety of natural habitats and achieve a likewise diverse set of sensing goals. One aspect in which bat biosonar appears to differ from man-made system is its heavy reliance on diffraction-based beamforming with intricate baffle shapes. In-vivo observations of these shapes have provided evidence for non-rigid baffle deformations that coincide with the diffraction of the outgoing or incoming waves. In horseshoe bats, a bat group with one of the most elaborate biosonar systems, the emission baffles have been found to twitch in synchrony with each pulse emission. On the reception side, the animals’ outer ears can likewise be deformed while the incoming pulses impinge on them. The acoustic effects of the outer ear motions can be characterized using frequency-domain characterizations (beampatterns) revealing significant acoustic effects. However, a time-domain characterization of a biomimetic prototype has shown even stronger effects. Hence, it may be hypothesized that these mobile baffle provide a substrate for a time-variant strategy for the encoding of sensory information - a hypothesis that is well suited for further exploration with bioinspired sensing technology.

Some of Morpho butterfly species have a mysterious physical coloration. Their blue color has both high reflectivity (>60%) and a single color in too wide angular range (> ± 40° from the normal), which are contradicting with each other from viewpoint of the optical interference. A key to the mechanism of the specific Morpho-color was suggested to be the nano-randomness in arrangement of the nanostructures on its scale, which prevents the rainbow interference. However, concrete optical roles of the nano-randomness remained still unclear. Using finite-difference time-domain (FDTD) analysis, we have recently investigated the optical role of different kinds of randomness in the nanostructure on the Morpho butterfly’s scale. The results revealed clearly several independent roles of different kinds of randomness. On the other hand, by inproving the accuracy of simulation, we have found new aspects on the analysis, especially for the number of random components (nano-trees). These new aspects will give important hint and caution to futher simulation on the optical properties of this specific colorations that have wide potential applications. The direction obtained by the numerical simulations to analyze optically complex random structures will serve not only to understand the scientific principles, but also to design the optical properties of artificial materials.

The Emerald Ash Borer (EAB), Agrilus planipennis, is an invasive species threatening the ash trees of North America. EABs exhibit a mating behavior in which the flying male will spot a stationary female at rest, then execute a pouncing maneuver where he dives sharply onto the female. It is thought that this pouncing behavior is cued by some visual signal from the elytra of the EAB. A method for replicating the elytra of the EAB as artificial decoys was devised and implemented. In a field experiment, four types of bioreplicated EAB decoys with a dead EAB female to determine if the former were effective at cuing the pouncing behavior in males.

In an attempt to produce a less invasive alternative to current ventricular assistive devices, this study proposes a novel intra-ventricular VAD for end stage congestive heart failure patients. VADs are approved by FDA as Bridge to Transplantation Therapy (BTT), Bridge to Recovery Therapy (BRT) and permanent or Destination Therapy (DT) for patients at NYHA Class IV as an alternative to heart transplant. While all current devices require open-heart surgery, the flexible structure and thin active membrane, made of Ionic Polymer Metal Composites (IPMC) and Shape Memory Alloys (SMA), enables transcatheter implantation and thus eliminates the need for a thoracotomy. Moreover, exerting almost no shear stress on blood cells and having no stagnant points reduces the risk of hemolysis and thrombosis. In order to define the average working conditions and physiological needs, hemodynamics of an eligible patient is first examined. Different motion mechanisms are then evaluated to find the one that has the maximum volume displacement and also mimics the natural motion of the heart. As the preliminary evaluation of the device, 1D results of an FEM solution of the governing differential equation of the electrochemical behavior of IPMCs are found to check the compliancy of IPMCs with those needs defined by hemodynamic and motion analyses. Although modeling and simulation results provided in this paper are for left ventricle, the same progressive design and test processes are also applicable for the right ventricle.

As the improvement of people's living standard, more and more is required of the superior quality dairy products. An important indicator that gets more and more attention to measure the quality of dairy products is ingredient content of nutrients in dairy products. One of main component of milk, the concentration of milk fat is of great significance for light scattering measurements. The photomicrograph of the different homogeneous state of milk fat solution with is different concentrations obtained by using high magnification optical microscope. And the particle size distribution of different homogeneous state and different concentrations of milk fat solution are analyzed. Based on the principle of light scattering technique for the detection of milk composition, as well as analysis of the physical and chemical properties of milk fat solution, the energy spectrum, absorption spectrum, the transmittance spectrum of the different homogeneous state and the different concentrations of milk fat solution are determined by the dual-beam spectrophotometer (TJ270-60). Then the effects of fat solution concentration, particle size distribution and homogeneous state on the light scattering intensity are analyzed. Furthermore, it is derived the relationships among milk fat solution concentration with energy, absorption and transmittance based on experimental results. This study will bring a progress in processing quality control of product, and contribute to promote the development of China's dairy industry for bringing practical significance and great economic benefits.

Vertical aligned carbon nanotube array was fabricated by catalytic chemical vapor deposition and then transferred onto flexible polymer substrates with an effective polymer intermediate. Adhesion performance of the flexible CNTs dry adhesive was measured with a multifunctional material adhesion/friction performance test platform. A micron-drag process was implemented during the test in order to help increasing the side contact area of CNTs, which in turn results in an enhanced adhesion. The transferred CNTs on flexible PET substrates have an increasing adaptability without damaging its original structure. The normal and shear adhesion performance were both enhanced dramatically due to the pre-drag process. The fabrication and test methods provided here will plays an important role in the realization of CNTs dry adhesive for gecko-mimetic climbing robots.

Over the past decade, there has been considerable interest in miniaturizing aircraft to create a class of extremely small, robotic vehicles with a gross mass on the order of tens of grams and a dimension on the order of tens of centimeters. These are collectively refered to as micro aerial vehicles (MAVs) or microflyers. Because the size of microflyers is on the same order as that of small birds and large insects, engineers are turning to nature for inspiration. Bioinspired concepts make use of structural or aerodynamic mechanisms that are observed in insects and birds, such as elastic energy storage and unsteady aerodynamics. Biomimetic concepts attempt to replicate the form and function of natural flyers, such as flapping-wing propulsion and external appearance. This paper reviews recent developments in the area of man-made microflyers. The design space for microflyers will be described, along with fundamental physical limits to miniaturization. Key aerodynamic phenomena at the scale of microflyers will be highlighted. Because the focus is on bioinspiration and biomimetics, scaled-down versions of conventional aircraft, such as fixed wing micro air vehicles and microhelicopters will not be addressed. A few representative bioinspired and biomimetic microflyer concepts developed by researchers will be described in detail. Finally, some of the sensing mechanisms used by natural flyers that are being implemented in man-made microflyers will be discussed.

In this paper, we examine the effect of non-sinusoidal flapping motion caused by click mechanism and compared it to a sinusoidal flapping motion. Many had observed and described the click mechanism through insect’s anatomy. Through theoretical models and numerical studies, some dismissed its effect on flapping efficiency, while others predicted better thrust generation with it. Without concrete experimental proof, the argument is hypothetical. This work showed the benefits of the click mechanism by experiment, with its simple compliant thorax designed using carbon fiber and polyimide film. The click mechanism system is designed like a thin elastic plate which was compressed until bent, with its center point stable at either the top most extreme or the bottom most extreme positions. ‘Clicking’ occurs when the plate center is moved forcibly from one extreme to the other. Before it passes the midpoint, the plate center moves slowly as it tends to return to the original extreme and resist the displacement. When moved passed the midpoint, it now tends to move to the other extreme, together with the external force, resulting in a fast, snapping ‘click’ to the other extreme. Hence, the clicking prototype showed a sudden high increase in wing flap speed when it is moved beyond midpoint towards the other end. It also showed quick wing reversal and is able to produce consistent large wing stroke (~115°). The clicking prototype, which weighs 3.78g, produces a higher thrust of 2.9g at a flapping frequency of 19Hz. In comparison, a 3.26g prototype of sinusoidal flapping motion with similar design configuration produces only 2.2g of thrust at 19Hz.

Dragonflies exhibit glide and flapping flight modes using wings composed of corrugated flat plates. It has previously been shown that corrugated airfoils exhibit superior lift-to-drag ratios over conventional airfoils at Reynolds numbers of 8,000. The literature also shows a significant sensitivity of aerodynamic performance with Reynolds number and flight condition. These sensitivities may mean that the corrugations are a compromise between structural and aerodynamic characteristics due to their stiffening effect. We consider the effect at a higher Reynolds number of 34,000 which is close to where our unmanned aircraft with a conventional airfoil currently operates. We compare the aerodynamics of a corrugated geometry, with a flat plate and a conventional low Reynolds number airfoil. The results confirm that surface corrugation of the baseline shape has limited aerodynamic efficiency at low angles-of-attack relative to the flat plate and the Eppler E61 profile. Avenues for further design analysis with eventual focus on shape optimisation is needed to confirm the role of corrugation in sustaining efficient flight modes at an even lower Re and across an extended angle of attack test range.

The investigation of unsteady aerodynamics is becoming a more attractive topic of research in enhancing flight capabilities. Natural flyers such as birds and insects can undergo flight maneuvers that are very difficult or impossible to accomplish with man-made flyers and current classical aerodynamic theory. Modeling the unsteady phenomena produced by flapping wings is important to the understanding of these maneuvers, with possible applications to aircraft flight. We investigate numerically simulating the unsteady aerodynamics generated by flapping wings using the two seperate approaches of rotational lift and dynamic stall. A low order quasi-steady model based on rotational lift and a revised version based on dynamic stall are presented. Both concepts are analyzed using simulated results, with experimental data produced with matching kinematics as a basis of comparison. The numerically generated force curves are used to explore the characteristics and distinguishing features of both approaches, as well as how well they capture the salient features of the experimentally produced forces.

In this study, we develop a flexible multibody model of the Hawkmoth Manduca Sexta and its six degrees of freedom (6- DOF) flight dynamic simulation environment. The wings of the Hawkmoth model are constructed as a flexible structure which has similar structural dynamic characteristics to the real Hawkmoth wings. The other body components: head, thorax, and abdomen are also modeled independently to consider each component’s mass and inertia properties. Based on this flexible multibody dynamics environment, a wing kinematics that enables a hovering flight of the Hawkmoth model is searched. This kinematics is compared with experimentally measured wing kinematics from literature, and the result shows that a slight modification to the measured wing kinematics is sufficient to reproduce the hovering flight of the Hawkmoth model. The 6-DOF flight dynamic states at the hovering condition are also computed and these state variables are compared with those of a rigid-winged Hawkmoth model to see the effect of the flexibility on the flight dynamics. Here, the rigid- and flexible-winged Hawkmoth models are the same except for the wing flexibility. A qualitative and comparative analysis is performed on the 6-DOF flight states during the hovering flight between the two Hawkmoth models, and the effect of wing flexibility on the flight dynamics is addressed.

Kinesins are nano-sized biological motors which are responsible for active transport in cells. A single kinesin molecule is able to transport its cargo about 1 μm in the absence of external loads. However, kinesins perform much longer range transport in cells by working collectively. One of the most important mechanisms involved in this long transport are the binding and unbinding of kinesins to microtubules. Kinesins realize the transport by a repetitive mechanochemical cycle. In this study, the unbinding probabilities corresponding to each mechanochemical state of kinesin are calculated. The statistical characterization of the instants and locations of binding are captured by computing the probability of unbound kinesin being at given locations. The forces acting on kinesins affect binding and unbinding. This effect is also considered in this study. It reveals that the length of the transport is significantly longer when multiple proteins cooperatively transport the same cargo.

Novel biologically-inspired energy harvesting devices constructed with lipid bilayer membranes are studied. Recently the research group has proposed the use of biomolecular unit cells consisting of encapsulated droplets with a lipid bilayer formed at their interfaces, stabilized between the two aqueous compartments. This allows for the rapid study and assessment of the characteristics of the individual unit cell, the insertion of various transport proteins and peptides that shape the response of the unit cell, and the construction of complex networks of these biomolecular systems. The goal of this work is to develop and study methods for constructing energy relevant devices through these biomolecular networks. These networks are highly tailorable, and allow the researcher to alter the embedded proteins/peptides in the lipid bilayer, the bilayer dimensions through the application of compressive forces, and the salt concentrations in the droplets. This allows for a high degree of control over their attributes and outputs. These systems also exhibit collective properties through large networks of the unit cells, allowing for complex sensing and actuation behavior not exhibited by single cells. This paper provides an overview of the development of a model for predicting the performance and output of these energy relevant biomolecular networks as well as preliminary experimental results that demonstrate some of the concepts in action.