High-sensitivity interferometry

High-sensitivity interferometric techniques are considered for non-destructive testing applications. The methods enable quantitative measurement of optical path variations, resulting from dynamic changes within the test object. [Continues.

Advanced quartz crystal microbalance techniques applied to calixarene sensing membranes.

Several Quartz Crystal Microbalance (QCM) measurement techniques in conjunction with a series of calix[4]resorcinarene sensing membranes have been successfully exploited for the detection of volatile organic solvents at vapour concentrations below their lower explosive level.The impedance analysis technique involves the measurement of the electrical properties of the QCM around the resonant frequencies of crystal. Subsequent fitting of the measured spectra to an equivalent circuit allows parameters directly related to mass loading and the mechanical properties (viscosity) of the film to be obtained. An experimental setup which allows the real time in situ extraction of these parameters has been developed.It has been shown that unique changes in mass loading and the films viscoelastic properties caused by the adsorption of target vapours into a calix[4]resorcinarene C15H31 sensing membrane can be detected. In some cases this facilitates both the detection and discrimination of target vapours using a single QCM sensing element. The changes in the films mechanical properties are believed to be caused by capillary condensation of vapours at values below saturated vapour pressure inside the nano-porous calix[4]resorcinarene film matrix.The work is extended by the use of the sensor array technique. In the first instance frequency only measurements are used. Four QCM have been coated with calix[4]resorcinarene compounds with different hydrocarbon chain lengths and exposed to range of organic vapours. The variation in chain length produces selectivity between the sensing membranes, and leads to the classification of all the tested organic vapours using a feed forward multilayer Artificial Neural Network. The trained network successfully classified over 98% of the test data.The additional measurement of film dissipation using impedance analysis/QCMD shows interesting phenomena. An unexpected increase in mechanical stiffness of the film is observed for small chain length C[4]RA compounds (CH3) on vapour sorption. A speculative model has been proposed relating the chain length and effective cavity size to the observed phenomena.An alternative low cost multi parameter measurement set up has also been developed using the QCMD principle. The crystal is driven from an external oscillatory source and subsequently disconnected. The resonant frequency and dissipation factor can be extracted from the decaying sinusoid signal. This approach eliminates the need for expensive network analysers. An additional multiplexing circuit has been combined with the QCMD technique and allows both the frequency and dissipation factor of several crystals to be measured in pseudo real time. This makes the system ideally suited for multi parameter array measurements.The basis for a discriminative explosive vapour sensor based on calix[4]resorcinarene membranes has been investigated and promising results for future development have been obtained. The exact adsorption mechanisms are however complex and althoughspeculative models have been proposed, further research is suggested to fully characterize the complete adsorption process and the mechanical changes taking place within the film

A Novel, Contactless, Portable “Spot-Check” Device Accurately Measures Respiratory Rate

Respiratory rate (RR) is an important vital sign used in the assessment of acutely ill patients. It is also used as to predict serious deterioration in a patient's clinical condition. Convenient electronic devices exist for measurement of pulse, blood pressure, oxygen saturation and temperature. Although devices which measure RR exist, none has entered everyday clinical practice. We developed a contactless portable respiratory rate monitor (CPRM) and evaluated the agreement in respiratory rate measurements between existing methods and our new device. The CPRM uses thermal anemometry to measure breath signals during inspiration and expiration. RR data were collected from 52 healthy adult volunteers using respiratory inductance plethysmography (RIP) bands (established contact method), visual counting of chest movements (established non-contact method) and the CPRM (new method), simultaneously. Two differently shaped funnel attachments were evaluated for each volunteer. Data showed good agreement between measurements from the CPRM and the gold standard RIP, with intra-class correlation coefficient (ICC): 0.836, mean difference 0.46 and 95% limits of agreement of -5.90 to 6.83. When separate air inlet funnels of the CPRM were analysed, stronger agreement was seen with an elliptical air inlet; ICC 0.908, mean difference 0.37 with 95% limits of agreement -4.35 to 5.08. A contactless device for accurately and quickly measuring respiratory rate will be an important triage tool in the clinical assessment of patients. More testing is needed to explore the reasons for outlying measurements and to evaluate in the clinical setting

Student sensor lab at home: safe repurposing of your gadgets

The COVID-19 pandemic imposed various restrictions on the accessibility of conventional teaching laboratories. Enabling learning and experimenting at home became necessary to support the practical element of students’ learning. Unfortunately, it is not viable to provide or share a fully featured sensor lab to every student because of the prohibitive costs involved. Therefore, repurposing electronic devices that are common to students can bring about the sought-after practical learning experience without the hefty price tag. In distinction to the conventional lab instruments though, consumer grade devices are not designed for use with external sensors and/or electronic circuitry. They are not professionally maintained, do not undergo periodic safety tests and are not calibrated. Nevertheless, nearly all modern computers, laptops, tablets or smartphones are equipped with high quality audio inputs and outputs that can generate and record signals in the audible frequency range (20 Hz – 20 kHz). Despite cutting off the direct currents completely, this range might be sufficient for working with a variety of sensors. In this presentation we look at the possibilities of making sure that such repurposing by design prevents any potential harm to the learner and to her or his personal equipment. These features seem essential for unsupervised alone experimenting and avoiding damage to expensive devices

Mycotoxin biosensor based on optical planar waveguide

The research aim of this work is to develop a simple and highly sensitive optical biosensor for detection of mycotoxins. This sensor is built on a planar waveguide operating on the polarization interferometry principle, i.e., detecting a phase shift between p- and s-components of polarized light developed during the binding of analyte molecules. The operation of the proposed sensor is similar to that of a Mach⁻Zehnder interferometer, while its design is much simpler and it does not require splitting the waveguide into two arms. The refractive index sensitivity of the polarization interferometer sensor was in the range of 5200 radians per refractive index unit (RIU). Several tests were conducted to detect ochratoxin A (OTA) at different concentrations in direct immunoassay with specific antibodies immobilized in the sensing window. The lowest concentration of OTA of 0.01 ng/mL caused a phase shift of nearly one period. The results obtained prove high sensitivity of the sensors, which are capable of detecting even lower concentrations of mycotoxins at the ppt (part-per-trillion) level

Medical Devices for Measuring Respiratory Rate in Children: a Review

Respiratory rate is an important vital sign used for diagnosing illnesses in children as well as prioritising patient care. All children presenting acutely to hospital should have a respiratory rate measured as part of their initial and ongoing assessment. However measuring the respiratory rate remains a subjective assessment and in children can be liable to measurement error especially if the child is uncooperative. Devices to measure respiratory rate exist but many provide only an estimate of respiratory rate due to the associated methodological complexities. Some devices are used within the intensive care, post-operative or more specialised investigatory settings none however have made their way into the everyday clinical setting. A non-contact device may be better tolerated in children and not cause undue stress distorting the measurement. Further validation and adaption to the acute clinical setting is needed before such devices can supersede current methods

Transient evoked otoacoustic emissions in adults: a comparison between two test protocols

This study compares the performance of the Quickscreen and Default protocols of the ILO-96 Otodynamics Analyzer in recording transient evoked otoacoustic emissions (TEOAEs) from adults using clinical decision analysis. Data were collected from 25 males (mean age = 29.0 years, SD = 6.8) and 35 females (mean age = 28.1 years, SD = 9.6). The results showed that the mean signal-to-noise ratios obtained from the Quickscreen were significantly greater than those from the Default protocol at 1,2, and 4 kHz. The comparison of the performance of the two protocols, based on the results using receiver operating characteristics curves, revealed a higher performance of the Quickscreen than the Default protocol at 1 and 4 kHz but not at 2 kHz. In view of the enhanced performance of the Quickscreen over the Default protocol in general, the routine use of the Default protocol for testing adults in audiology clinics should be reconsidered

Prosthetics services in Uganda : a series of studies to inform the design of a low cost, but fit-for-purpose, body-powered prosthesis

The majority of people with upper limb absence (PWULA) live in lower, or middle-income countries (LMICs). However, efforts to develop improved prostheses have largely focused on electrically powered devices, sustainable deployment of which, in LMICs, is difficult. In the ‘Fit-for-purpose, affordable body-powered prostheses’ project, teams from the UK, Uganda and Jordan are developing mechanically-operated prostheses, optimised for LMICs, and establishing local methods for fabrication, fitting and evaluation. Here we first report on preliminary studies aimed at grounding the project in the reality of current prosthetics services and the experiences of people with limb absence in Uganda. Finally, we outline our ongoing work in the context of our findings. In our first two studies we reviewed current prosthetics and associated repair services. An issue which came up repeatedly was the difficulty faced by orthopaedic technologists in accessing componentry/materials. All specialised prosthetics components and materials are imported, often at a high cost. Purchasing does not appear to be well coordinated between centres, meaning potential economies of scale are not being fully exploited. Although there is supposed to be government funding for prosthetics, in practice budgets are often inadequate and a reliance on donations is common. The resource limitations mean Orthopaedic Technologists often resort to ad-hoc solutions; unsurprisingly perhaps, failures in prostheses were reported. In particular, lamination-based socket manufacture is very difficult, given the complexity (and cost) of the processes involved. Repair services are also limited, in part also due to problems accessing materials/components. Despite (or in part, as a result of) these challenges, the orthopaedic technologists are generally an extremely resourceful and multi-skilled group and there is genuine enthusiasm to see services improve. Further, there is a growth in interest and capabilities in the area of medical device innovation. In the third of our studies, we interviewed 17 PWULA and present preliminary results from the analysis of a subset of five participants. Firstly, we found that only 2 of the participants reported experience with using an upper limb prosthesis, again supporting the picture which emerged from the other studies. The findings illustrate the emergence of four key themes: a) attitude towards disability; b) barriers to prosthesis use; c) coping without a prosthesis; and d) communication with other PWULA. Although attitudes to those with limb loss varied, participants reported impacts in terms of social isolation and a mixed experience of emotions that appeared predominantly negative; barriers to prosthesis use were broader than just cost and functionality, and included a lack of training and psychological support; given that it is difficult to access an upper limb prosthesis, PWULA have found ways to perform daily life activities without relying on one; finally, most PWULA find the suggestion of communicating with other people with the same experience appealing. In our project we are addressing some of the issues found in the preliminary studies. To make socket manufacture less dependent on access to imported materials and specialised equipment, we are investigating the development of lattice-style, adjustable sockets, made from locally available materials. We are also investigating alternatives to the traditional harness-controlled, body-powered prosthetic hands. Given that clinicians have no objective means of evaluating the value of the prosthesis to their clients, we are testing the use of low-cost digital monitoring tools. We are also exploring the potential value of using mobile-phones to reduce the isolation of PWULA. Finally, we are exploring how these innovations may be translated into the Ugandan health setting

Tropical cyclone characteristics associated with extreme precipitation in the northern Philippines

The Philippines is exposed to Tropical Cyclones (TCs) throughout the year due to its location in the western North Pacific. While these TCs provide much-needed precipitation for the country’s hydrological cycle, extreme precipitation from TCs may also cause damaging hazards such as floods and landslides. This study examines the relationship between TC extreme precipitation and TC characteristics, including movement speed, intensity, and season, for westward-moving TCs crossing Luzon, northern Philippines. We measure extreme precipitation by the Weighted Precipitation Exceedance (WPE), calculated against a 95th percentile threshold, which considers both the magnitude and spatial extent of TC-related extreme precipitation. WPE has a significant, moderate positive relationship with TC intensity with a non-significant, weak negative relationship with movement speed. When TCs are classified by intensity one day before landfall (or pre-landfall), Typhoons (1-minute maximum sustained wind speed > 64 knots) tend to yield higher WPE than Non-Typhoons ( 11.38 knots). However, the relationship between pre-landfall TC intensity and WPE is more pronounced during June-September while there is no significant difference between the WPE of the Southwest Monsoon (June-September) and Northeast Monsoon (October-December) seasons. These results suggest that it is important to consider the pre-landfall cyclone movement speed, intensity, and season to anticipate extreme precipitation of incoming TCs. A decision table considering these factors is devised to aid in TC extreme precipitation forecasting

Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes.

Ketosis, the metabolic response to energy crisis, is a mechanism to sustain life by altering oxidative fuel selection. Often overlooked for its metabolic potential, ketosis is poorly understood outside of starvation or diabetic crisis. Thus, we studied the biochemical advantages of ketosis in humans using a ketone ester-based form of nutrition without the unwanted milieu of endogenous ketone body production by caloric or carbohydrate restriction. In five separate studies of 39 high-performance athletes, we show how this unique metabolic state improves physical endurance by altering fuel competition for oxidative respiration. Ketosis decreased muscle glycolysis and plasma lactate concentrations, while providing an alternative substrate for oxidative phosphorylation. Ketosis increased intramuscular triacylglycerol oxidation during exercise, even in the presence of normal muscle glycogen, co-ingested carbohydrate and elevated insulin. These findings may hold clues to greater human potential and a better understanding of fuel metabolism in health and disease