A rapid-response soft end effector inspired by the hummingbird beak

This is the final version. Available on open access from the Royal Society via the DOI in this recordData accessibility: Data (including the videos about the experiment) are available from Dryad: https://doi.org/10.5061/dryad.3bk3j9ktvSupplementary material is available online at https://doi.org/10.6084/m9.figshare.c.7402652Biology is a wellspring of inspiration in engineering design. This paper delves into the application of elastic instabilities—commonly used in biological systems to facilitate swift movement—as a power-amplification mechanism for soft robots. Specifically, inspired by the nonlinear mechanics of the hummingbird beak—and shedding further light on it—we design, build and test a novel, rapid-response, soft end effector. The hummingbird beak embodies the capacity for swift movement, achieving closure in less than 10ms . Previous work demonstrated that rapid movement is achieved through snap-through deformations, induced by muscular actuation of the beak’s root. Using nonlinear finite element simulations coupled with continuation algorithms, we unveil a representative portion of the equilibrium manifold of the beak-inspired structure. The exploration involves the application of a sequence of rotations as exerted by the hummingbird muscles. Specific emphasis is placed on pinpointing and tailoring the position along the manifold of the saddle-node bifurcation at which the onset of elastic instability triggers dynamic snap-through. We show the critical importance of the intermediate rotation input in the sequence, as it results in the accumulation of elastic energy that is then explosively released as kinetic energy upon snap-through. Informed by our numerical studies, we conduct experimental testing on a prototype end effector fabricated using a compliant material (thermoplastic polyurethane). The experimental results support the trends observed in the numerical simulations and demonstrate the effectiveness of the bio-inspired design. Specifically, we measure the energy transferred by the soft end effector to a pendulum, varying the input levels in the sequence of prescribed rotations. Additionally, we demonstrate a potential robotic application in scenarios demanding explosive action. From a mechanics perspective, our work sheds light on how pre-stress fields can enable swift movement in soft robotic systems with the potential to facilitate high input-to-output energy efficiency.University of BristolLeverhulme TrustRoyal Academy of Engineering (RAE

Quantifying efficient shape-shifting: Energy barrier measurement in multi-stable lattice metamaterials

This is the final version. Available on open access from Elsevier via the DOI in this recordData availability: Data are available at the University of Bristol data repository, data.bris, at https://doi.org/10.5523/bris.1n7g692ynrlht214cxm7yk77qiShape-shifting between multiple stable deformation states offers attractive pathways to design adaptive structures. Ideas have been conceptualised in diverse fields, including soft robotics and aerospace engineering. The success of shape-shifting relies on overcoming the energy barrier separating adjacent stable configurations, which necessitates efficient actuation strategies. Recently, multistable mechanical metamaterials have been designed with shape-shifting controlled by an actuator at the local scale, i.e with embedded actuation. This local, embedded actuation creates challenges for quantifying the energy barriers required for shape-shifting. Specifically, the local actuation requires a pair of forces with opposite directions and the direction of the forces must remain constant throughout the entire loading process. Moreover, the loading points must move freely in a direction perpendicular to the loading direction. We present a novel bi-axial test rig for a typical multi-stable lattice metamaterial that accurately determines the energy barrier between stable states by using an embedded actuator and inducing shape-shifting. Our experimental design features two independent actuation systems operating at different length scales: a primary one for a globally applied axial compression of the metamaterial, and a secondary local system for triggering shape-shifting between different stable configurations. Experimental data obtained using this bespoke test rig unveil the metamaterial’s response to local, embedded actuation. Excellent agreement with finite element simulations is observed, demonstrating the effectiveness of the test setup in providing measurements of the energy barrier. This work provides a valuable benchmark for measuring energy barriers in multi-stable metamaterials and paves the way for rigorous validation and verification of novel functional metamaterial and structures that leverage shape-shifting mechanisms.Leverhulme TrustRoyal Academy of Engineering (RAE)Exeter Technologies Group, University of ExeterSwansea UniversityEuropean Research Council (ERC

Disability in young adults following major trauma: 5 year follow up of survivors

BACKGROUND: Injuries are a major cause of mortality and morbidity in young people. Despite this, the long-term consequences for young survivors of severe injury are relatively unexplored. METHODS: Population based cohort study involving 5 year post injury structured interview of all cases of major trauma (Injury Severity Score > 15) identified retrospectively for 12 month period (1988 to 1989) within former Yorkshire Health Authority area of the United Kingdom. RESULTS: 125 individuals aged 11–24 years at time of injury were identified. Of these, 109 (87%) were interviewed. Only 20% (95% CI 14–29%) of those interviewed reported no disability. Mean Office of Population Census and Surveys (OPCS) disability score of the remainder was 7.5 (median 5.8, range 0.5 to 19.4). The most commonly encountered areas of disability were behaviour (54%, 95% CI 45–63%), intellectual functioning (39%, 95% CI 31–49%) and locomotion (29%, 95% CI 22–39%). Many respondents reported that their daily lives were adversely affected by their health problems for example, causing problems with work, 54% (95% CI 45–63%), or looking after the home, 28% (95% CI 21–38%). Higher OPCS scores were usually but not always associated with greater impact on daily activities. The burden of caring responsibilities fell largely on informal carers. 51% (95% CI 42–61%) of those interviewed would have liked additional help to cope with their injury and disability. CONCLUSION: The study has revealed significant disability amongst a cohort of young people 5 years post severe injury. Whilst many of these young people were coping well with the consequences of their injuries, others reported continuing problems with the activities of daily life. The factors underpinning the young people's differing experiences and social outcome should be explored

The priming effect of extracellular UTP on human neutrophils: Role of calcium released from thapsigargin-sensitive intracellular stores

P2Y2 receptors, which are equally responsive to ATP and UTP, can trigger intracellular signaling events, such as intracellular calcium mobilization and mitogen-activated protein (MAP) kinase phosphorylation in polymorphonuclear leukocytes (PMN). Moreover, extracellular nucleotides have been shown to prime chemoattractant-induced superoxide production. The aim of our study was to investigate the mechanism responsible for the priming effect of extracellular nucleotides on reactive oxygen species (ROS) production induced in human neutrophils by two different chemoattractants: formyl-methionyl-leucyl-phenylalanine (fMLP) and interleukin-8 (IL-8). Nucleotide-induced priming of ROS production was concentration- and time-dependent. When UTP was added to neutrophil suspensions prior to chemoattractant, the increase of the response reached the maximum at 1 min of pre-incubation with the nucleotide. UTP potentiated the phosphorylation of p44/42 and p38 MAP kinases induced by chemoattractants, however the P2 receptor-mediated potentiation of ROS production was still detectable in the presence of a SB203580 or U0126, supporting the view that MAP kinases do not play a major role in regulating the nucleotide-induced effect. In the presence of thapsigargin, an inhibitor of the ubiquitous sarco-endoplasmic reticulum Ca2+-ATPases in mammalian cells, the effect of fMLP was not affected, but UTP-induced priming was abolished, suggesting that the release of calcium from thapsigargin-sensitive intracellular stores is essential for nucleotide-induced priming in human neutrophils

Use of patients’ classification instruments: analysis of the brazilian production of knowledge

Objective To analyze the production of scientific knowledge about the use of patients’ classification instruments in care and management practice in Brazil. Method Integrative literature review with databases search in: Latin American and Caribbean Literature on Health Sciences (LILACS), Medical Literature Analysis and Retrieval System on-line (MEDLINE), Cumulative Index to Nursing and Allied Health Literature (CINAHL) and SCOPUS, between January 2002 through December 2013. Results 1,194 studies were found, 31 met the inclusion criteria. We observed a higher number of studies in the category care plans and workload (n=15), followed by the category evaluation of psychometric properties (n=14). Conclusion Brazilian knowledge production has not yet investigated some purposes of using instruments for classifying patients in professional nursing practice. The identification of unexplored areas can guide future research on the topic