Optical planar waveguide sensor with integrated digitally-printed light coupling-in and readout elements

Optical planar waveguide sensors, able to detect and process information from the environment in a fast, cost-effective, and remote fashion, are of great interest currently in different application areas including security, metrology, automotive, aerospace, consumer electronics, energy, environment, or health. Integration of networks of these systems together with other optical elements, such as light sources, readout, or detection systems, in a planar waveguide geometry is greatly demanded towards more compact, portable, and versatile sensing platforms. Herein, we report an optical temperature sensor with a planar waveguide architecture integrating inkjet-printed luminescent light coupling-in and readout elements with matched emission and excitation. The first luminescent element, when illuminated with light in its absorption band, emits light that is partially coupled into the propagation modes of the planar waveguide. Remote excitation of this element can be performed without the need for special alignment of the light source. A thermoresponsive liquid crystal-based film regulates the amount of light coupled out from the planar waveguide at the sensing location. The second luminescent element partly absorbs the waveguided light that reaches its location and emits at longer wavelengths, serving as a temperature readout element through luminescence intensity measurements. Overall, the ability of inkjet technology to digitally print luminescent elements demonstrates great potential for the integration and miniaturization of light coupling-in and readout elements in optical planar waveguide sensing platforms

Photomechanical response under physiological conditions of azobenzene-containing 4D-printed liquid crystal elastomer actuators

Soft and mechanically responsive actuators hold the promise to revolutionize the design and manufacturing of devices in the areas of microfluidics, soft robotics and biomedical engineering. In many of these applications, the actuators need to operate in a wet environment that can strongly affect their performance. In this paper, we report on the photomechanical response in a biological buffer of azobenzene-containing liquid crystal elastomer (LCE)-based actuators, prepared by four-dimensional (4D) printing. Although the photothermal contribution to the photoresponse is largely cancelled by the heat withdrawing capacity of the employed buffer, a significant photoinduced reversible contraction, in the range of 7% of its initial length, has been achieved under load, taking just a few seconds to reach half of the maximum contraction. Effective photomechanical work performance under physiological conditions has, therefore, been demonstrated in the 4D-printed actuators. Advantageously, the photomechanical response is not sensitive to salts present in the buffer differently to hydrogels with responses highly dependent on the fluid composition. Our work highlights the capabilities of photomechanical actuators, created using 4D printing, when operating under physiological conditions, thus showing their potential for application in the microfluidics and biomedical fields.</p

Gait phenotypes in paediatric hereditary spastic paraplegia revealed by dynamic time warping analysis and random forests

The Hereditary Spastic Paraplegias (HSP) are a group of heterogeneous disorders with a wide spectrum of underlying neural pathology, and hence HSP patients express a variety of gait abnormalities. Classification of these phenotypes May help in monitoring disease progression and personalizing therapies. This is currently managed by measuring values of some kinematic and spatio-temporal parameters at certain moments during the gait cycle, either in the doctor´s surgery room or after very precise measurements produced by instrumental gait analysis (IGA). These methods, however, do not provide information about the whole structure of the gait cycle. Classification of the similarities among time series of IGA measured values of sagittal joint positions throughout the whole gait cycle can be achieved by hierarchical clustering analysis based on multivariate dynamic time warping (DTW). Random forests can estimate which are the most important isolated parameters to predict the classification revealed by DTW, since clinicians need to refer to them in their daily practice. We acquired time series of pelvic, hip, knee, ankle and forefoot sagittal angular positions from 26 HSP and 33 healthy children with an optokinetic IGA system. DTW revealed six gait patterns with different degrees of impairment of walking speed, cadence and gait cycle distribution and related with patient’s age, sex, GMFCS stage, concurrence of polyneuropathy and abnormal visual evoked potentials or corpus callosum. The most important parameters to differentiate patterns were mean pelvic tilt and hip flexion at initial contact. Longer time of support, decreased values of hip extension and increased knee flexion at initial contact can differentiate the mildest, near to normal HSP gait phenotype and the normal healthy one. Increased values of knee flexion at initial contact and delayed peak of knee flexion are important factors to distinguish GMFCS stages I from II- III and concurrence of polyneuropathyDGA was in receipt of a grant from Sociedad Española de Neurología Pediátrica (SENEP). Publication fee was supported by EUF-ONCE-UAM and Asociación Española de Paraparesia Espástica Familiar (AEPEF)

Characterizing Normal and Pathological Gait through Permutation Entropy

Altres ajuts: We acknowledge the contribution of the children and their families who generously collaborated to build the gait dataset used in this study. We are also grateful to Michael R. Paul for kindly editing the English style of this manuscript. The acquisition and processing of gait data were funded by Escuela de Fisioterapia de la ONCE-UAM, through a private donation, and Agencia de Evaluación de Tecnologías Sanitarias (Instituto de Salud Carlos III), .Cerebral palsy is a physical impairment stemming from a brain lesion at perinatal time, most of the time resulting in gait abnormalities: the first cause of severe disability in childhood. Gait study, and instrumental gait analysis in particular, has been receiving increasing attention in the last few years, for being the complex result of the interactions between different brain motor areas and thus a proxy in the understanding of the underlying neural dynamics. Yet, and in spite of its importance, little is still known about how the brain adapts to cerebral palsy and to its impaired gait and, consequently, about the best strategies for mitigating the disability. In this contribution, we present the hitherto first analysis of joint kinematics data using permutation entropy, comparing cerebral palsy children with a set of matched control subjects. We find a significant increase in the permutation entropy for the former group, thus indicating a more complex and erratic neural control of joints and a non-trivial relationship between the permutation entropy and the gait speed. We further show how this information theory measure can be used to train a data mining model able to forecast the child's condition. We finally discuss the relevance of these results in clinical applications and specifically in the design of personalized medicine interventions

Surface Modifications of COP-Based Microfluidic Devices for Improved Immobilization of Hydrogel Proteins: Long Term 3D Culture with Contractile Cell Types and Ischemia Model.

Hydrogel confinement is critical in microfluidics to generate gradients, as cell remodelling process boundaries the development of biological models such as ischemia or fibrosis. Here, we test the immobilization efficiency of collagen hydrogels cells embedded to treated COP-based microfluidic devices to preserve 3D structure and avoid gel contraction

Characterization of multiple sclerosis lesions with distinct clinical correlates through quantitative diffusion MRI

Diffusion magnetic resonance imaging can reveal quantitative information about the tissue changes in multiple sclerosis. The recently developed multi-compartment spherical mean technique can map different microscopic properties based only on local diffusion signals, and it may provide specific information on the underlying microstructural modifications that arise in multiple sclerosis. Given that the lesions in multiple sclerosis may reflect different degrees of damage, we hypothesized that quantitative diffusion maps may help characterize the severity of lesions "in vivo" and correlate these to an individual's clinical profile. We evaluated this in a cohort of 59 multiple sclerosis patients (62% female, mean age 44.7 years), for whom demographic and disease information was obtained, and who underwent a comprehensive physical and cognitive evaluation. The magnetic resonance imaging protocol included conventional sequences to define focal lesions, and multi-shell diffusion imaging was used with b-values of 1000, 2000 and 3000 s/mm2 in 180 encoding directions. Quantitative diffusion properties on a macro- and micro-scale were used to discriminate distinct types of lesions through a k-means clustering algorithm, and the number and volume of those lesion types were correlated with parameters of the disease. The combination of diffusion tensor imaging metrics (fractional anisotropy and radial diffusivity) and multi-compartment spherical mean technique values (microscopic fractional anisotropy and intra-neurite volume fraction) differentiated two type of lesions, with a prediction strength of 0.931. The B-type lesions had larger diffusion changes compared to the A-type lesions, irrespective of their location (P < 0.001). The number of A and B type lesions was similar, although in juxtacortical areas B-type lesions predominated (60%, P < 0.001). Also, the percentage of B-type lesion volume was higher (64%, P < 0.001), indicating that these lesions were larger. The number and volume of B-type lesions was related to the severity of disease evolution, clinical disability and cognitive decline (P = 0.004, Bonferroni correction). Specifically, more and larger B-type lesions were correlated with a worse Multiple Sclerosis Severity Score, cerebellar function and cognitive performance. Thus, by combining several microscopic and macroscopic diffusion properties, the severity of damage within focal lesions can be characterized, further contributing to our understanding of the mechanisms that drive disease evolution. Accordingly, the classification of lesion types has the potential to permit more specific and better-targeted treatment of patients with multiple sclerosis

Muscle imaging in laminopathies: Synthesis study identifies meaningful muscles for follow-up

Introduction: Particular fibroadipose infiltration patterns have been recently described by muscle imaging in congenital and later onset forms of LMNA-related muscular dystrophies (LMNA-RD). Methods: Scores for fibroadipose infiltration of 23 lower limb muscles in 34 patients with LMNA-RD were collected from heat maps of 2 previous studies. Scoring systems were homogenized. Relationships between muscle infiltration and disease duration and age of onset were modeled with random forests. Results: The pattern of infiltration differs according to disease duration but not to age of disease onset. The muscles whose progression best predicts disease duration were semitendinosus, biceps femoris long head, gluteus medius, and semimembranosus. Discussion: In LMNA-RD, our synthetic analysis of lower limb muscle infiltration did not find major differences between forms with different ages of onset but allowed the identification of muscles with characteristic infiltration during disease progression. Monitoring of these specific muscles by quantitative MRI may provide useful imaging biomarkers in LMNA-RD. Muscle Nerve 58:812-817, 201

Future of additive manufacturing: Overview of 4D and 3D printed smart and advanced materials and their applications

© 2020 Elsevier B.V. 4D printing is an emerging field in additive manufacturing of time responsive programmable materials. The combination of 3D printing technologies with materials that can transform and possess shape memory and self-healing capabilities means the potential to manufacture dynamic structures readily for a myriad of applications. The benefits of using multifunctional materials in 4D printing create opportunities for solutions in demanding environments including outer space, and extreme weather conditions where human intervention is not possible. The current progress of 4D printable smart materials and their stimuli-responsive capabilities are overviewed in this paper, including the discussion of shape-memory materials, metamaterials, and self-healing materials and their responses to thermal, pH, moisture, light, magnetic and electrical exposures. Potential applications of such systems have been explored to include advancements in health monitoring, electrical devices, deployable structures, soft robotics and tuneable metamaterials

External evaluation of gait and functional changes after a single-session multiple myofibrotenotomy in school-aged children with spastic diplegia

Introducción. Unos 23.000 pacientes con espasticidad han optado voluntariamente por la miofibrotomía múltiple (MFM), una técnica alternativa consistente en seccionar tejidos blandos para liberar restricciones articulares. Iniciada por Ulzibat (Rusia), se realiza fuera de controles clínicos ortodoxos. Objetivo. Evaluar externamente los efectos de la MFM sobre la funcionalidad motora y la marcha. Pacientes y métodos. Estudio observacional autocontrolado que evalúa cambios en variables funcionales –Gross Motor Function Classification System, dimensión E de la Gross Motor Function Measure (GMFM) y Functional Mobility Scale– y 32 parámetros de marcha (medidos mediante análisis instrumental) en 22 escolares con diplejía espástica (edad mediana: 9 años y 6 meses; Q1-Q3: 7 años y 11 meses a 11 años y 6 meses) cuyos padres optaron por una MFM (mediana de observación: 4 meses; rango: 3-7 meses). Resultados. El análisis de conglomerados jerárquicos utilizado para determinar patrones topográficos de cortes en los pacientes detectó que los cirujanos aplicaban a cada paciente uno de tres conjuntos de cortes. Analizados los tres grupos de pacientes, se observó que un grupo empeoró globalmente y una mejora significativa general en la dimensión E del GMFM (diferencia de mediana: 4,86%; intervalo de confianza al 95% = 0-6,94%) tras la MFM. Algunos parámetros de la marcha se normalizaron significativamente (izquierda: rango flexión-cadera, máxima dorsiflexión en apoyo; derecha: velocidad, rotación pélvica media en apoyo y máxima dorsiflexión en apoyo). Conclusiones. Estos resultados no apoyan ni justifican el uso de la MFM como opción para el tratamiento de la espasticidad. Insistimos en que esta técnica debe evitarse fuera de protocolos de estudio. Sin embargo, los resultados asientan una base objetiva para justificar la realización de un ensayo clínico y estudios observacionales a largo plazoIntroduction. About 23,000 patients with spasticity voluntarily chose to undergo a multiple myofiberotomy (MMF), which is an alternative technique consisting in sectioning soft tissues in order to relieve restrictions in joint movements. This technique, first employed by Ulzibat (Russia), is performed outside orthodox clinical controls. Aims. To perform an external evaluation of the effects of MMF on motor functionality and gait. Patients and methods. The study was self-controlled and observation-based and was designed to evaluate the changes in functional variables –Gross Motor Function Classification System, E-dimension of the Gross Motor Function Measure (GMFM) and the Functional Mobility Scale– and 32 gait parameters (measured using analytical instruments) in 22 schoolchildren with spastic diplegia (mean age: 9 years and 6 months; Q1-Q3: 7 years and 11 months to 11 years and 6 months) whose parents opted for an MMF (median of observation: 4 months; range: 3-7 months). Results. The analysis of hierarchical conglomerates used to determine topographic cut patterns in patients revealed that the surgeons applied one of three sets of cuts to each patient. On analysing the three groups of patients, it was observed that one group worsened overall and another underwent a general significant improvement in the E-dimension of the GMFM (difference of median: 4.86%; 95% confidence interval = 0-6.94%) after the MMF. Some of the gait parameters became significantly normalised (left: hip-flexion range, maximum dorsiflexion with support; right: speed, mean pelvic rotation with support and maximum dorsiflexion with support). Conclusions. These findings do not back up or justify the use of MMF as a therapeutic option to treat spasticity. It has to be stressed that this technique must be avoided outside study protocols. Nevertheless, results do lay an objective base that may justify a clinical trial and long-term observation-based studiesFinanciado por AETES (PI05/90123