This systematic review explores the use of on-animal sensors in sheep and their potential application in objective welfare monitoring. The key questions posed were: To what extent can current scientific knowledge inform a sensor-based approach to welfare evaluations? And, how might this knowledge shape development of commercial monitoring systems? These questions were explored through retrospective classification of published sensor applications using The Five Domains (FD) Model as a framework for animal welfare assessment. A total of 71 studies were reviewed. The results indicate studies specifically evaluating the use of sensors for welfare assessment are limited, though many experiments could still be related to some aspect of welfare. The assessment of sensor utilisation revealed the greatest proportion of applications within the ‘Behaviour’ Domain (90.1%; n = 64), and the lowest within the ‘Health’ (25.4%; n = 18) and ‘Mental state’ Domains (25.4%; n = 18). The review also highlights how different sensor types (location, motion or physiological) differ in their applicability for welfare assessment. This paper is the first to classify published sensor applications using the FD Model as a framework and highlights the potential for sensor technology in sheep welfare monitoring. The results suggest that any attempt to create a commercial sensor-based system for objective welfare assessment will require the integration of more than one sensor type, particularly if multiple Domains are to be addressed.

Recent technological advances enable the collection of intensive longitudinal data. This scoping review aimed to provide an overview of methods for collecting intensive time series data in mental health research as well as basic principles, current applications, target constructs, and statistical methods for this type of data.

In January 2021, the database MEDLINE was searched. Original articles were identified that (1) used active or passive data collection methods to gather intensive longitudinal data in daily life, (2) had a minimum sample size of N ⩾ 100 participants, and (3) included individuals with subclinical or clinical mental health problems.

In total, 3799 original articles were identified, of which 174 met inclusion criteria. The most widely used methods were diary techniques (e.g. Experience Sampling Methodology), various types of sensors (e.g. accelerometer), and app usage data. Target constructs included affect, various symptom domains, cognitive processes, sleep, dysfunctional behaviour, physical activity, and social media use. There was strong evidence on feasibility of, and high compliance with, active and passive data collection methods in diverse clinical settings and groups. Study designs, sampling schedules, and measures varied considerably across studies, limiting the generalisability of findings.

Gathering intensive longitudinal data has significant potential to advance mental health research. However, more methodological research is required to establish and meet critical quality standards in this rapidly evolving field. Advanced approaches such as digital phenotyping, ecological momentary interventions, and machine-learning methods will be required to efficiently use intensive longitudinal data and deliver personalised digital interventions and services for improving public mental health.

We previously described an efficient, lightweight and flexible electro-thermal system, based on directly drawn carbon nanotube web (CNT web), as part of an icing protection system for carbon fibre reinforced polymer (CFRP) composite aircraft structures. The location of the heating elements on critical lifting surface leading edges or nacelle intake lips makes them particularly susceptible to impact damage, which may leave no visible mark. This makes it desirable to have both a mechanism for identifying the location of damage to the CNT structure (and by inference, potential damage to the underlying CFRP) and a process for restoring the CNT heater to full operation. With the CNT web acting as a sensor, impact damage is identified by an increase in electrical resistance and, particularly, by infrared imaging, which reveals a cold spot or zone depending upon the CNT web layup. Whereas a unidirectional CNT web layup exhibits a large increase in resistance and loss of a full width band of operation, a cross ply quasi-isotropic CNT web arrangement suffers only a small increase in resistance and a loss of function that is highly localised to the damaged area. A novel methodology, based on dispersed CNT in resin, is described for repairing and reconnecting the CNT structure and restoring functionality. A CNT web-based electro-thermal element was applied to the leading edge of a representative carbon-fibre composite wing section to demonstrate the flexibility of this system.

With the characteristics of full autonomy and no accumulated errors, polarisation navigation shows tremendous prospects in underwater scenarios. In this paper, inspired by the polarisation vision of aquatic organisms, a novel point-source polarisation sensor with high spectral adaptability (400 nm–760 nm) is designed for underwater orientation. To enhance the environmental applicability of the underwater polarisation sensor, a novel sensor model based on the underwater light intensity attenuation coefficient and optical coupling coefficient is established. In addition, concerned with the influence of light intensity uncertainty on sensor performance underwater, an antagonistic polarisation algorithm is adopted for the first time, to improve the accuracy of angle of polarisation and degree of polarisation in the low signal-to-noise ratio environment underwater. Finally, indoor and outdoor experiments are carried out to evaluate the performance of the designed polarisation sensor. The results show that the designed point-source polarisation sensor can acquire polarised light and be used for heading determination underwater.

Sensors based on metamaterial absorbers are very promising when it comes to high sensitivity and quality factor, cost, and ease of fabrication. The absorbers could be used to sense physical parameters such as temperature, pressure, density as well as they could be used for determining electromagnetic properties of materials and their characterization. In this work, an attempt has been made to explore the various possible applications of these sensors. Metamaterial-based sensors are very popular for its diverse applications in areas such as biomedical, chemical industry, food quality testing, agriculture. Split-ring resonators with various shapes and topologies are the most frequently used structures where the sensing principle is based on electromagnetic interaction of the material under test with the resonator. Overcoming the design challenges using metamaterial sensors involving several constraints such as cost, compactness, reusability, ease in fabrication, and robustness is also addressed.

Growing zinc oxide (ZnO) nanowires (NWs) on yarns promotes smart sensing and creates opportunities for new applications. ZnO NWs sensing performance is influenced by its dimensions, which can be tailored by controlling the growth parameters. In this study, we investigated the effect of the growth parameters (time, temperature, and precursor concentration ratio) on the NWs’ morphology, dimensions, and piezoelectric performance. Our results showed that ZnO NWs produced with 6 and 9 h had long nanowires; however, they mainly got tangled with the nanowires on the adjacent fibers and peeled-off the fiber surface. Growth at a 1:1 precursor concentration ratio for 9 h produced the same nanowires’ length (~3 μm) as growth at a 3:1 precursor concentration ratio for 3 h. Among all of the studied growth conditions, ZnO NWs produced with a 3:1 precursor concentration ratio at 90 °C for 3 h showed uniform dimensions and stable electrical charge output.

The capability of borospherene to detect radioactive pollutants (radon and radium) is investigated utilizing density functional theory and nonequilibrium Green's function regime. The quantum transport is evaluated by calculating the density of states, chemical potential, transmission and molecular energy spectra, highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap, electron densities, current–voltage curve, and differential and quantum conductance. LUMO-mediated transmission is observed in all the cases. The conduction considerably declines in B40 molecular junction doped with radioactive pollutants in comparison to pure B40 molecular junction. This decrease in conduction is due to reduced electron density and higher chemical potential in doped B40 junctions. Due to different values of current and differential conductance, we propose utilization of B40 in detecting the presence of radioactive pollutants in underground water. Also, all molecular junctions assay lifting of Coulomb blockade at equilibrium state; thus, these devices can be effectively utilized in single-electron transistor applications.

Diversity of production systems and specific socio-economic barriers are key reasons explaining why the implementation of new technologies in small ruminants, despite being needed and beneficial for farmers, is harder than in other livestock species. There are, however, helpful peculiarities where small ruminants are concerned: the compulsory use of electronic identification created a unique scenario in Europe in which all small ruminant breeding stock became searchable by appropriate sensing solutions, and the largest small ruminant population in the world is located in Asia, close to the areas producing new technologies. Notwithstanding, only a few research initiatives and literature reviews have addressed the development of new technologies in small ruminants. This Research Reflection focuses on small ruminants (with emphasis on dairy goats and sheep) and reviews in a non-exhaustive way the basic concepts, the currently available sensor solutions and the structure and elements needed for the implementation of sensor-based husbandry decision support. Finally, some examples of results obtained using several sensor solutions adapted from large animals or newly developed for small ruminants are discussed. Significant room for improvement is recognized and a large number of multiple-sensor solutions are expected to be developed in the relatively near future.

Iron oxide nanoparticles presenting colloidal stability in water were prepared through precipitation and then surface-functionalized with varying citric acid (CA) concentrations (0.10, 0.25, 0.50, and 0.70 g/mL). CA introduced functionality and minimized agglomeration. Iron oxide nanoparticles with colloidal stability in water at physiological pH were obtained after functionalization with 0.25–0.70 g/mL CA, whereas iron oxide nanoparticles without stability in water were obtained after functionalization with 0.10 g/mL CA. An electrode for glucose detection was fabricated by self-assembling colloidal-stable γ-Fe2O3 NP–CA in water on indium tin oxide (ITO) glass, followed by a glucose oxidase (GOx) and Nafion layer. The optimal functionalization of the γ-Fe2O3 NPs was obtained at a CA concentration of 0.25 g/mL. The electrochemical properties and electrocatalytic behavior of the modified electrode designated as Nafion/GOx/γ-Fe2O3 NP–0.25 CA/ITO were then evaluated. The electrode showed high sensitivity for glucose detection of 995.57 and 5.81 µA/(mM cm2) within the linear ranges of 0.1–5.0 µM and 5.0 µM–20.0 mM, respectively. The modified electrode also demonstrated a low limit of detection, good repeatability of 2.5% (n = 10), and sufficient reproducibility of 3.2% (n = 5).

C-reactive protein (CRP) and cardiac troponin I (cTnI) biomolecules represent the earliest enzymes that appear in the blood when a cardiac injury occurs. Real-time and selective detection of these biomarkers is essential for the prediction and detection of cardiovascular diseases at an early stage. Here we report on the label-free specific detection of both proteins at picomolar concentrations using fabricated nanowire-based biosensors. We demonstrate a novel functionalization technique based on the attachment of dibenzocyclooctyne (DBCO)-linked troponin-specific aptamers to azide-functionalized silicon (Si) nanowire (NW) surface. Due to the fast and reliable immobilization of cTnI-specific aptamers and CRP-specific antibodies on the Si NWs, the fabricated devices can rapidly detect target biomolecules demonstrating high sensitivity. We confirm the attachment of proteins to the surface of Si NWs by atomic force microscopy (AFM). Moreover, we demonstrate that nanowire structures of different sizes enable the detection of biomarkers in a wide concentration range (from 1 pg/ml to 1 µg/ml), corresponding to CRP and cTnI elevation levels during the early stage of disease formation.

This paper discusses new components and approaches to make stretchable optical fiber sensors better meet the power and washability requirements of wearables. First, an all-polymer quick connector allows the light source and photosensor to be quickly detached for washing. Second, the paper investigates the possibility of driving the sensors using ambient light instead of an onboard light source. While optical strain sensors and touch sensors have advantages over electronic ones in wet environments, and the intrinsic stretchability of the fibers is useful for soft robotics and highly conformal wearables, the typical light-emitting diode (LED) light source consumes more power than an electronic resistive or capacitive strain sensor. In this work, ambient light of uniform but unknown intensity is demonstrated to drive an elastomeric optical touch sensor in a differential configuration.

Pneumonia has contributed greatly to child mortality, especially among children under the ages of five in sub-Saharan Africa, killing more children than the number of children dying from HIV/AIDS. The current methods of diagnosing pneumonia involved physical examination and chest x-ray which are limited by low accuracy, high error margins, higher cost, and stands the risks of inducing cancer. In this work, a low-cost, non-invasive biomedical device was designed and developed to improve accuracy in diagnosing pneumonia. The device functions to detect fluid in a lung consolidated by pneumonia. Dry grouting sponge was used as a phantom for a healthy lung, while a wet sponge was used to mimic a pneumonia-consolidated lung. Surface exciter was used to produce sound waves which travelled through one side of the phantom and are detected on the other end using an electronic stethoscope. The signals detected were digitally analyzed using MATLAB and AUDACITY software. The differences in resonant frequencies from the power spectrum analysis of sound waves as they travelled through the sponges were used to distinguish between a pneumonia-consolidated lung and a healthy lung.

Using water as an example, it is shown that monitoring the change in the loss tangent is a high sensitive method that allows determining the activation energy of relaxation processes in nanostructured water with high accuracy. The use of sensors, the electrodes of which are not in direct contact with the liquid under study is shown to be reasonable. The conditions for obtaining reliable information on the properties of water and its solutions are also justified, namely: measurements should be carried out using pulse methods for several seconds, and then measurements should be stopped to avoid contamination of the solutions studied by electrolysis products. The method of monitoring the magnitude of the loss tangent at fixed frequencies allows the acidity of solutions (pH value) to be controlled at the same time without using specialized instruments for acidity studying.

We demonstrate the fabrication, by exclusive means of inkjet-printing, of capacitive relative humidity sensors on flexible, plastic substrate. These sensors can be successfully used for the measurement of relative-humidity in both air and common soil. We also show that the same technique may be used for the fabrication of the same type of sensors on the surface of the leaves of Elægnus Ebbingei (silverberry).Our results demonstrate the suitability of leaves as substrate for printed electronics and pave the way to the next generation of sensors to be used in fields such as agriculture and flower farming.

Light Detection and Ranging (LiDAR) is a primary sensor for autonomous vehicles to recognize surroundings. It detects near-infrared (NIR) light pulses, typically at 905nm, which is emitted and reflected by surrounding objects. Here, the fact of the matter is that conventional black or dark-tone cars with extremely low NIR reflection are hard to be detected by LiDAR and endanger the future highway. In this work, we propose to use platelet-shaped effect pigments with visible absorption and NIR reflectivity. Copper(Ⅱ) oxide and Silicon dioxide multilayer are theoretically investigated with different numbers of layers and thicknesses. The optimized structures appear various dark-tone colors with high NIR-reflectivity over 90%.

Propagating inhomogeneous electromagnetic waves called surface plasmon polaritons (SPPs) can be excited by free-space beams on corrugated conducting surfaces at resonance angles determined by corrugation period, permittivity, and optical frequency. SPPs are coupled to and co-propagate with surface charge displacements. Complete electrical isolation of individual conducting corrugations prevents the charge displacement necessary to sustain an SPP, such that excitation resonances of traveling SPPs are absent. However, SPPs can be excited via electric induction if a smooth conducting surface exists below and nearby the isolated conducting corrugations. The dependence of SPP excitation resonances on that separation is experimentally investigated here at long-wave infrared wavelengths. We find that excitation resonances for traveling SPPs broaden and disappear as the dielectric’s physical thickness is increased beyond ~1% of the free-space wavelength. The resonance line width increases with refractive index and optical thickness of the dielectric.

Nanostructures are considered to have great potential and are widely used in energy storage and sensing devices, and atomic layer deposition (ALD) is of great help for better nanostructure fabrications. ALD can help to preserve the original properties of materials, and, meanwhile, the excellent film quality, nanoscale precise thickness control, and high conformality also play important role in fabrication process. To enhance the performance of energy storage and sensor devices, ALD has been used in directly fabricating active nanostructures, depositing protective passivation layers, etc. ALD is a convenient technique which has been widely engaged in energy-related fields including electrochemical conversion and storage, as well as in sensor and biosensors. The related research interest is increasing significantly. In this review, we summarize some of the latest works on ALD for batteries, supercapacitors, and sensors, and demonstrate the benefits of ALD comprehensively. In these devices, different materials are deposited by ALD under different conditions to achieve better battery performance, higher supercapacitor capacitance, and higher sensitivity. This review fully presents the strengths of ALD and its application in energy storage and sensing devices and proposes the future prospects for this rapidly developing technology.

The hierarchical Au-loaded SnO2 nanoflowers were synthesized using a new developed self-reductive hydrothermal method, of which the gas-sensing properties were enhanced significantly. The SnO2 hierarchical nanoflowers were composed of well-defined nanosheets with a specific surface area of around 84 m2/g. Gas sensors made of pure and Au-doped SnO2 were fabricated, and their gas-sensing properties were characterized. The 1.0 at.% Au-loaded SnO2 sensor prepared by the new developed self-reductive method showed much more excellent selectivity toward ethanol at 200 °C than the one prepared with the conventional hydrothermal method. Its response to ethanol was around 3 times higher than that of the pure SnO2 sensor. A very wide detection range of 1–500 ppm for ethanol, good repeatability, and long-term stability were also approved.