Stickiness in shear: stiffness, shape, and sealing in bioinspired suction cups affect shear performance on diverse surfaces.

Aquatic organisms utilizing attachment often contend with unpredictable environments that can dislodge them from substrates. To counter these forces, many organisms (e.g. fish, cephalopods) have evolved suction-based organs for adhesion. Morphology is diverse, with some disc shapes deviating from a circle to more ovate designs. Inspired by the diversity of multiple aquatic species, we investigated how bioinspired cups with different disc shapes performed in shear loading conditions. These experiments highlighted pertinent physical characteristics found in biological discs (regions of stiffness, flattened margins, a sealing rim), as well as ecologically relevant shearing conditions. Disc shapes of fabricated cups included a standard circle, ellipses, and other bioinspired designs. To consider the effects of sealing, these stiff silicone cups were produced with and without a soft rim. Cups were tested using a force-sensing robotic arm, which directionally sheared them across surfaces of varying roughness and compliance in wet conditions while measuring force. In multiple surface and shearing conditions, elliptical and teardrop shapes outperformed the circle, which suggests that disc shape and distribution of stiffness may play an important role in resisting shear. Additionally, incorporating a soft rim increased cup performance on rougher substrates, highlighting interactions between the cup materials and surfaces asperities. To better understand how these cup designs may resist shear, we also utilized a visualization technique (frustrated total internal reflection; FTIR) to quantify how contact area evolves as the cup is sheared.

Are Linguistic Prediction Deficits Characteristic of Adults with Dyslexia?

Individuals with dyslexia show deficits in phonological abilities, rapid automatized naming, short-term/working memory, processing speed, and some aspects of sensory and visual processing. There is currently one report in the literature that individuals with dyslexia also show impairments in linguistic prediction. The current study sought to investigate prediction in language processing in dyslexia. Forty-one adults with dyslexia and 43 typically-developing controls participated. In the experiment, participants made speeded-acceptability judgements in sentences with word final cloze manipulations. The final word was a high-cloze probability word, a low-cloze probability word, or a semantically anomalous word. Reaction time from the onset of the final word to participants' response was recorded. Results indicated that individuals with dyslexia showed longer reaction times, and crucially, they showed clear differences from controls in low predictability sentences, which is consistent with deficits in linguistic prediction. Conclusions focus on the mechanism supporting prediction in language comprehension and possible reasons why individuals with dyslexia show less prediction.

Surface Actuation and Sensing of a Tensegrity Structure Using Robotic Skins.

Tensegrity robots comprising solid rods connected by tensile cables are of interest due to their flexible and robust nature, which potentially makes them suitable for uneven and unpredictable environments where traditional robots often struggle. Much progress has been made toward attaining locomotion with tensegrity robots. However, measuring the shape of a dynamic tensegrity without the use of external hardware remains a challenge. Here we show how robotic skins may be attached around the exterior of a tensegrity structure, to both control and measure its shape from its surface. The robotic skins are planar, skin-like membranes with integrated actuators and sensors, which we use to transform a passive tensegrity structure into an active tensegrity robot that performs tasks such as locomotion. In addition, sensors placed on the ends of the tensegrity rods are used to directly measure orientation relative to the ground. The hardware and algorithms presented herein thus provide a platform for surface-driven actuation and intrinsic state estimation of tensegrity structures, which we hope will enable future tensegrity robots to execute precise closed-loop motions in real-world environments.

Sustainable manufacturing of sensors onto soft systems using self-coagulating conductive Pickering emulsions.

Compliant sensors based on composite materials are necessary components for geometrically complex systems such as wearable devices or soft robots. Composite materials consisting of polymer matrices and conductive fillers have facilitated the manufacture of compliant sensors due to their potential to be scaled in printing processes. Printing composite materials generally entails the use of solvents, such as toluene or cyclohexane, to dissolve the polymer resin and thin down the material to a printable viscosity. However, such solvents cause swelling and decomposition of most polymer substrates, limiting the utility of the composite materials. Moreover, many such conventional solvents are toxic or otherwise present health hazards. Here, sustainable manufacturing of sensors is reported, which uses an ethanol-based Pickering emulsion that spontaneously coagulates and forms a conductive composite. The Pickering emulsion consists of emulsified polymer precursors stabilized by conductive nanoparticles in an ethanol carrier. Upon evaporation of the ethanol, the precursors are released, which then coalesce amid nanoparticle networks and spontaneously polymerize in contact with the atmospheric moisture. We printed the self-coagulating conductive Pickering emulsion onto a variety of soft polymeric systems, including all-soft actuators and conventional textiles, to sensitize these systems. The resulting compliant sensors exhibit high strain sensitivity with negligible hysteresis, making them suitable for wearable and robotic applications.

Oxidation of Gallium-based Liquid Metal Alloys by Water.

Gallium alloys with other low melting point metals, such as indium or tin, to form room-temperature liquid eutectic systems. The gallium in the alloys rapidly forms a thin surface oxide when exposed to ambient oxygen. This surface oxide has been previously exploited for self-stabilization of liquid metal nanoparticles, retention of metastable shapes, and imparting stimuli-responsive behavior to the alloy surface. In this work, we study the effect of water as an oxidant and its role in defining the alloy surface chemistry. We identify several pathways that can lead to the formation of gallium oxide hydroxide (GaOOH) crystallites, which may be undesirable in many applications. Furthermore, we find that some crystallite formation pathways can be reinforced by typical top-down particle synthesis techniques like sonication. This improved understanding of interfacial interactions provides critical insight for process design and implementation of advanced devices that utilize the unique coupling of flexibility and conductivity offered by these gallium-based liquid metal alloys.

Graphene-based encapsulation of liquid metal particles.

Liquid metals are a promising functional material due to their unique combination of metallic properties and fluidity at room temperature. They are of interest in wide-ranging fields including stretchable and flexible electronics, reconfigurable devices, microfluidics, biomedicine, material synthesis, and catalysis. Transformation of bulk liquid metal into particles has enabled further advances by allowing access to a broader palette of fabrication techniques for device manufacture or by increasing area available for surface-based applications. For gallium-based liquid metal alloys, particle stabilization is typically achieved by the oxide that forms spontaneously on the surface, even when only trace amounts of oxygen are present. The utility of the particles formed is governed by the chemical, electrical, and mechanical properties of this oxide. To overcome some of the intrinsic limitations of the native oxide, it is demonstrated here for the first time that 2D graphene-based materials can encapsulate liquid metal particles during fabrication and imbue them with previously unattainable properties. This outer encapsulation layer is used to physically stabilize particles in a broad range of pH environments, modify the particles' mechanical behavior, and control the electrical behavior of resulting films. This demonstration of graphene-based encapsulation of liquid metal particles represents a first foray into the creation of a suite of hybridized 2D material coated liquid metal particles.

Laser Sintering of Liquid Metal Nanoparticles for Scalable Manufacturing of Soft and Flexible Electronics.

Soft, flexible, and stretchable electronics are needed to transmit power and information, and track dynamic poses in next-generation wearables, soft robots, and biocompatible devices. Liquid metal has emerged as a promising material for these applications due to its high conductivity and liquid phase state at room temperature; however, surface oxidation of liquid metal gives it unique behaviors that are often incompatible with scalable manufacturing techniques. This paper reports a rapid and scalable approach to fabricate soft and flexible electronics composed of liquid metal. Compared to other liquid metal patterning approaches, this approach has the advantages of compatibility with a variety of substrates, ease of scalability, and efficiency through automated processes. Nonconductive liquid metal nanoparticle films are sintered into electrically conductive patterns by use of a focused laser beam to rupture and ablate particle oxide shells, and allow their liquid metal cores to escape and coalesce. The laser sintering phenomenon is investigated through comparison with focused ion beam sintering and by studying the effects of thermal propagation in sintered films. The effects of laser fluence, nanoparticle size, film thickness, and substrate material on resistance of the sintered films are evaluated. Several devices are fabricated to demonstrate the electrical stability of laser-patterned liquid metal traces under flexing, multilayer circuits, and intricately patterned circuits. This work merges the precision, consistency, and speed of laser manufacturing with the material benefits of liquid conductors on elastic substrates to demonstrate decisive progress toward commercial-scale manufacturing of soft electronics.

OmniSkins: Robotic skins that turn inanimate objects into multifunctional robots.

Robots generally excel at specific tasks in structured environments but lack the versatility and the adaptability required to interact with and locomote within the natural world. To increase versatility in robot design, we present robotic skins that can wrap around arbitrary soft bodies to induce the desired motions and deformations. Robotic skins integrate actuation and sensing into a single conformable material and may be leveraged to create a multitude of controllable soft robots with different functions or gaits to accommodate the demands of different environments. We show that attaching the same robotic skin to a soft body in different ways, or to different soft bodies, leads to distinct motions. Further, we show that combining multiple robotic skins enables complex motions and functions. We demonstrate the versatility of this soft robot design approach in a wide range of applications-including manipulation tasks, locomotion, and wearables-using the same two-dimensional (2D) robotic skins reconfigured on the surface of various 3D soft, inanimate objects.

An endoscopic modification of the simultaneous 'above and below' approach to large pituitary adenomas.

Surgical resections of large-to-giant pituitary adenomas (PA) are technically challenging procedures. Tumors with a fibrous consistency or 'hour-glass' configurations are particularly difficult to remove completely and safely through the transsphenoidal route alone. Although the transcranial approach can facilitate the removal of a large suprasellar mass, it may be associated with significant bleeding within the intradural space. A simultaneous microscopic transcranial and transsphenoidal approach has been described as an alternative surgical strategy. We have further modified this 'above and below' approach by adopting endoscopic techniques for the transsphenoidal part of the procedure. This modified approach has the advantages of requiring only one operating microscope, and permitting freer maneuvers and easier orientation for both surgical teams. We present two patients successfully treated with this approach. Complete tumor removal was achieved and both patients achieved satisfactory functional recovery.

Limonoid content of sour orange varieties.

BACKGROUND: Modern Citrus cultivars are thought to have arisen from three parents: the pummelo, the mandarin, and citron. Taxological and genetic data support that sweet and sour oranges share a common parentage. However, as their name suggests, the organoleptic properties of the fruit from these two families is distinctly different. Analysis of the limonoid content of sour orange varieties has been limited. RESULTS: Juice samples prepared from a selection of sour orange cultivars were evaluated for their limonoid A-ring lactone, aglycone, and glucoside contents. Limonoate A-ring lactone concentrations ranged from 11.1 to 44. 9 mg L⁻¹, whereas nomilinoate A-ring lactone levels were found not to exceed 1.2 mg L⁻¹. Total limonoid aglycone and total limonoid glucoside concentrations varied from 2.4 to 18.4 mg L⁻¹ and from 149.0 to 612.3 mg L⁻¹, respectively. Limonoid glucoside profiling by liquid chromatography-mass spectrometry suggest that the sour oranges are distinctly different from sweet oranges and other citrus species. CONCLUSION: Limonoid aglycone and A-ring contents across sweet and sour oranges are similar, whereas limonoid glucoside profiles are distinctly different. Juice prepared from Citrus maderaspatana had the highest limonoid concentrations among the samples tested and could potentially be used for the isolation of limonoid A-ring lactones and glucosides.

The perception of complex tones by a false killer whale (Pseudorca crassidens).

Complex tonal whistles are frequently produced by some odontocete species. However, no experimental evidence exists regarding the detection of complex tones or the discrimination of harmonic frequencies by a marine mammal. The objectives of this investigation were to examine the ability of a false killer whale to discriminate pure tones from complex tones and to determine the minimum intensity level of a harmonic tone required for the whale to make the discrimination. The study was conducted with a go/no-go modified staircase procedure. The different stimuli were complex tones with a fundamental frequency of 5 kHz with one to five harmonic frequencies. The results from this complex tone discrimination task demonstrated: (1) that the false killer whale was able to discriminate a 5 kHz pure tone from a complex tone with up to five harmonics, and (2) that discrimination thresholds or minimum intensity levels exist for each harmonic combination measured. These results indicate that both frequency level and harmonic content may have contributed to the false killer whale's discrimination of complex tones.

Polar bear Ursus maritimus hearing measured with auditory evoked potentials.

While there has been recent concern about the effects of sound on marine mammals, including polar bears, there are no data available measuring the hearing of any bear. The in-air hearing of three polar bears was measured using evoked auditory potentials obtained while tone pips were played to three individually anaesthetized bears at the Kolmården Djurpark. Hearing was tested in half-octave steps from 1 to 22.5 kHz. Measurements were not obtainable at 1 kHz and best sensitivity was found in the range from 11.2-22.5 kHz. Considering the tone pips were short and background noise measurements were available, absolute measurements were estimated based on an assumed mammalian integration time of 300 ms. These data show sensitive hearing in the polar bear over a wide frequency range and should cause those concerned with the introduction of anthropogenic noise into the polar bear's environment to operate with caution.

Temporal resolution of the Risso's dolphin, Grampus griseus, auditory system.

Toothed whales and dolphins (Odontocetes) are known to echolocate, producing short, broadband clicks and receiving the corresponding echoes, at extremely rapid rates. Auditory evoked potentials (AEP) and broadband click stimuli were used to determine the modulation rate transfer function (MRTF) of a neonate Risso's dolphin, Grampus griseus, thus estimating the dolphin's temporal resolution, and quantifying its physiological delay to sound stimuli. The Risso's dolphin followed sound stimuli up to 1,000 Hz with a second peak response at 500 Hz. A weighted MRTF reflected that the animal followed a broad range of rates from 100 to 1,000 Hz, but beyond 1,250 Hz the animal's hearing response was simply an onset/offset response. Similar to other mammals, the dolphin's AEP response to a single stimulus was a series of waves. The delay of the first wave, PI, was 2.76 ms and the duration of the multi-peaked response was 4.13 ms. The MRTF was similar in shape to other marine mammals except that the response delay was among the fastest measured. Results predicted that the Risso's dolphin should have the ability to follow clicks and echoes while foraging at close range.

Behavioral and auditory evoked potential audiograms of a false killer whale (Pseudorca crassidens).

Behavioral and auditory evoked potential (AEP) audiograms of a false killer whale were measured using the same subject and experimental conditions. The objective was to compare and assess the correspondence of auditory thresholds collected by behavioral and electrophysiological techniques. Behavioral audiograms used 3-s pure-tone stimuli from 4 to 45 kHz, and were conducted with a go/no-go modified staircase procedure. AEP audiograms used 20-ms sinusoidally amplitude-modulated tone bursts from 4 to 45 kHz, and the electrophysiological responses were received through gold disc electrodes in rubber suction cups. The behavioral data were reliable and repeatable, with the region of best sensitivity between 16 and 24 kHz and peak sensitivity at 20 kHz. The AEP audiograms produced thresholds that were also consistent over time, with range of best sensitivity from 16 to 22.5 kHz and peak sensitivity at 22.5 kHz. Behavioral thresholds were always lower than AEP thresholds. However, AEP audiograms were completed in a shorter amount of time with minimum participation from the animal. These data indicated that behavioral and AEP techniques can be used successfully and interchangeably to measure cetacean hearing sensitivity.

Hearing measurements from a stranded infant Risso's dolphin, Grampus griseus.

An infant Risso's dolphin (Grampus griseus) was rescued from the beach in Southern Portugal, and an audiogram was measured using auditory evoked potentials (AEP) and envelope following response (EFR) techniques for frequencies from 4 to 150 kHz. The stimuli used were custom sinusoidally amplitude-modulated (SAM) tone-bursts, and the AEP responses were collected, averaged and analyzed to quantify the animal's physiological response and, thereby, hearing thresholds. The infant animal showed a wide range of best sensitivity, with the lowest threshold of 49.5 dB re. 1 microPa at 90 kHz. The audiogram showed a typical mammalian union or logical sum-shape with a gradual, low-frequency slope of 16.4 dB octave-1 and a sharp high-frequency increase of 95 dB octave-1. When compared with an audiogram of an older Risso's dolphin obtained using behavioral methods, the threshold values at upper frequencies were much lower for this infant animal, and this infant heard higher frequencies. These results redefine the hearing capabilities of Risso's dolphins by demonstrating very high-frequency sensitivity.