Train the trainer: improving health education for children and adolescents in Eswatini.

Background: Eswatini has the highest HIV prevalence in the world. One issue at the root of health in Eswatini is a lack of basic health knowledge among children and adolescents, which amplifies the likelihood of disease transmission and poor health outcomes. Objectives: To address the lack of basic health education and to improve health knowledge, we developed and evaluated a medical education program to train shepherds (train-the-trainer) who are supporting children and adolescents at local CarePoints. Methods: To determine the change between pre-test scores and post-test scores, both a paired t-test and mixed-effects regression were performed. Results: The program had 67 total participants, mostly female (67.2%), with an average age of 27.1 years. Following the medical education program, participants had a statistically significant increase in post-training scores. Years of prior schooling, age, and gender did not show a statistically significant effect on post-training scores. Conclusion: Teaching basic health education knowledge to CarePoint shepherds is effective to increase their knowledge and awareness with respect to relevant health topics. This model of directed medical education could be expanded to other community members in Eswatini to bridge gaps in health knowledge and disease awareness. A similar model could be employed in other developing countries with limited health education and limited access to health information.

Swollen Lower Limbs in Patients with Negative Pitting Test Leg Oedema: Prediction of Water Displacement Changes by Anthropometry and Bioimpedance Spectroscopy.

The assessment of lower limb oedema almost always involves measuring leg volume, and the gold-standard for this is the water displacement technique. As it is not very practical to use in a clinical routine, physicians prefer indirect methods such as anthropometric or bioimpedance measurements. In the case of "non-pitting" leg oedema, i.e. where the presence of oedema is not obvious, it may be challenging to estimate changes in leg volume using these methods separately. The combination of these two methods, however, gives interesting results, such as a new composite parameter that is much more robust and efficient than commonly used parameters.Clinical Relevance- This study demonstrates the benefit of using a composite anthropometric-impedimetric parameter to predict water displacement variations in the leg over the course of a day, rather than using parameters based solely on anthropometry or impedance. Our new parameter (C²-A²)/R0 showed a robust r² value of 61%, which is more than twice the r² values obtained using other simple or composite parameters.

INSA Wound Mapping System: II. Preliminary Porcine Results.

In the first paper, a versatile wound monitoring system, capable of mapping the extent of a wound and characterizing the tissues involved without removing the dressing, was presented. This was achieved through electrical impedance measurements, made via an electrode matrix embedded within the wound dressing.In this second paper, we present early mapping results obtained on porcine models. It was found that there was a good correlation between wound areas derived using digital image planimetry and those using a 49-electrode impedimetric electrode array.

A Practical Method to Reduce Electrode Mismatch Artefacts during 4-electrode BioImpedance Spectroscopy Measurements.

We present a novel and practical method of removing distortions due to electrode impedance mismatch encountered during 4-electrode bioimpedance spectroscopy (BIS) measurements. Recorded Iocalised, or even whole-body, tissue impedances often evidence high frequency artefacts which resemble additional capacitive or inductive behaviours. We show that making two impedance measurements with the same four electrodes, but by connecting them in different arrangements, we can cause either the observed high-frequency capacitive behaviour or the inductive behaviour. Additionally, simply calculating the mean of these two distorted data sets leads to a corrected, "artefact-free" impedance close to that expected. This correction method was validated on R-C networks (simulated as well as measured) and on biological tissue measurements (healthy forearm and oedematous leg). The described method was found valid using an SFB7 Impedimedo over a frequency range of 3 to $1000~\mathrm {k}\mathrm {H}\mathrm {z}$. It is possible that other impedance meters and frequency ranges could also benefit from this simple technique.

Effect of electrode material on the sensitivity of interdigitated electrodes used for Electrical Cell-Substrate Impedance Sensing technology.

This study explores the effect of the electrode material on the sensitivity of interdigitated electrodes (IDEs) used in Electrical Cell-Substrate Impedance Sensing (ECIS) technology. This technique is a label-free method to evaluate cellular activity of adherent cells. IDEs of gold (Au), indium tin oxide (ITO) and ITO functionalized with iridium oxide (IrOx) were characterized with impedance spectroscopy and their interfacial impedances were evaluated in potassium chloride (KCl) solutions. In parallel, ECIS measurements were performed on these three electrode materials during the proliferation of the human breast cancer cell line, MCF-7. The results indicate that the difference in sensitivity to MCF-7 of the three materials might be strongly correlated to their interfacial impedances. We found that ITO electrodes coated with IrOx show slightly higher sensitivity to MCF-7 breast cancer cells while still offering transparency compared to gold, which is considered the conventional material in ECIS devices.

Effect of compression stockings on cutaneous microcirculation: Evaluation based on measurements of the skin thermal conductivity.

OBJECTIVE: To study of the microcirculatory effects of elastic compression stockings. MATERIALS AND METHODS: In phlebology, laser Doppler techniques (flux or imaging) are widely used to investigate cutaneous microcirculation. It is a method used to explore microcirculation by detecting blood flow in skin capillaries. Flux and imaging instruments evaluate, non-invasively in real-time, the perfusion of cutaneous micro vessels. Such tools, well known by the vascular community, are not really suitable to our protocol which requires evaluation through the elastic compression stockings fabric. Therefore, we involve another instrument, called the Hematron (developed by Insa-Lyon, Biomedical Sensor Group, Nanotechnologies Institute of Lyon), to investigate the relationship between skin microcirculatory activities and external compression provided by elastic compression stockings. The Hematron measurement principle is based on the monitoring of the skin's thermal conductivity. This clinical study examined a group of 30 female subjects, aged 42 years ±2 years, who suffer from minor symptoms of chronic venous disease, classified as C0s, and C1s (CEAP). RESULTS: The resulting figures show, subsequent to the pressure exerted by elastic compression stockings, an improvement of microcirculatory activities observed in 83% of the subjects, and a decreased effect was detected in the remaining 17%. Among the total population, the global average increase of the skin's microcirculatory activities is evaluated at 7.63% ± 1.80% (p < 0.0001). CONCLUSION: The results from this study show that the pressure effects of elastic compression stockings has a direct influence on the skin's microcirculation within this female sample group having minor chronic venous insufficiency signs. Further investigations are required for a deeper understanding of the elastic compression stockings effects on the microcirculatory activity in venous diseases at other stages of pathology.

Localised impedance monitoring device for the remote clinical assessment of home-based dialysis patients.

BioImpedance Spectroscopy (BIS) has been clinically used to determine the hydrational status of patients undergoing haemodialysis (HD). In the present project we are developing a calf-localised, integrated impedimetric device to periodically and conveniently measure and transmit information on the hydrational status of home-based patients to a remote clinic. Surprisingly, we have found that simple postural changes before or during measurement lead to significant fluid shifts in the lower leg that are as important and as long lasting as the effects of haemodialysis. These must be taken into account if potentially hazardous errors are not to be made in assessing a patient's hydrational status.

Wearable impedance monitoring system for dialysis patients.

This paper describes the development and the validation of a prototype wearable miniaturized impedance monitoring system for remote monitoring in home-based dialysis patients. This device is intended to assess the hydration status of dialysis patients using calf impedance measurements. The system is based on the low-power AD8302 component. The impedance calibration procedure is described together with the Cole parameter estimation and the hydric volume estimation. Results are given on a test cell to validate the design and on preliminary calf measurements showing Cole parameter variations during hemodialysis.

Multifrequency right-side, localized and segmental BIA obtained with different bioimpedance analysers.

The aim of this study is to compare two commercial bioimpedance analysers, BioparHom Z-Métrix and Impedimed SFB7, measuring the impedance of three different body segments. The segments measured were 'right-side' (or 'whole-body'), 'segmental right-lower limb' and 'localized longitudinal right-quadriceps'. The comparison was made on electrical models of each segment, including electrode-skin impedance, and in vivo on nine healthy volunteers. Both devices are designed to measure right-side impedances and, in the present study, as the length of the segment investigated decreased, the accuracy of the impedance measured was found to decrease. The accuracy of the devices was calculated via measurements performed on RC networks of known values. It was found that adding electrode-skin contact impedances in the electrical model affected the accuracy by both devices.

Wearable sensor systems: the challenges.

Given the soaring costs associated with the treatment of ever more prevalent chronic disease, it is widely agreed that a revolution is required in health care provision. It is often thought that the necessary technology already exists for the home-based monitoring of such patients and that it is other factors which are holding back the more widespread clinical uptake of these new tools. The authors suggest that the necessary sensor-related technologies are often not as advanced as may first appear; certainly they are generally not adequate for the robust, long-term monitoring of patients under real-life conditions. An additional problem is the evident efforts to apply a given sensor and related technology platform to any and all monitoring scenarios without sufficient consideration of patient needs and the clinical requirements. The authors review the key sensing platforms and suggest the applications for which they are best suited.

Thermal parameters measurement on fire fighter: improvement of the monitoring system.

Real time monitoring of the thermal parameters on firefighter when operating is one of the ProeTEX project goals. The newly developed equipments in the framework of this project, integrate one temperature sensor and one heat flux sensor in the rescuer's outer garment. The environment in which firefighters operate is dangerous and the thermal risks can occur everywhere. Consequently the heat flux is so not necessarily symmetrical. To improve the thermally at risk situation detection, a modified platinum sensors array was integrated in the jacket in order to monitor simultaneously heat flux and temperature surrounding the rescuer. The sensors were placed in the most exposed area (shoulders and chest) to monitor thermal parameter in different directions. The heat flux is calculated from the temperature difference. This sensors array enables the detection of temperature increases and heat flux even when the heat source is localized on one side.

Thermal parameters measurement on fire fighter during intense fire exposition.

To improve rescuer safety, coordination and efficiency, the European program ProeTEX aims at developing new equipment for the intervention staff. This equipment is based on micro and nanotechnologies and consisted of smart textile integrated sensor to monitor physiological parameters, environment of the rescuer but also acquisition module and communication module. Thermal parameters are of primer interest. Internal temperature, external temperature and heat flux are relevant parameters to prevent heat stroke in fire fighter when exposed to intense fire. These parameters are recorded during fire exposition and highlight, on one hand, that the outer garment of fire fighters' equipment insulates the fire fighter from the external environment, and on the other hand, that the thermal monitoring is relevant.

Characterization of gold electrodes in phosphate buffered saline solution by impedance and noise measurements for biological applications.

Impedance spectroscopy and noise measurements have been used to study gold electrodes of three different surface areas in phosphate buffered saline (PBS) solution. The gold-PBS solution interface can be modeled by a charge transfer resistance in parallel with an interfacial constant phase element (CPE) which are in series with the solution resistance. The voltage noise fluctuations were analyzed using the fast Fourier transform (FFT) method. It is found that the voltage noise power is characterized by a 1/f(alpha) spectrum in the low frequency range. The value of alpha is observed to be double that of the CPE coefficient beta. The authors suggest a link between the interface impedance and the measured noise.

Fabrication of impedimetric sensors for label-free point-of-care immunoassay cardiac marker systems, with passive microfluidic delivery.

Miniaturised point-of-care cardiac marker sensors are being developed, based on impedimetric sensing of cardiac enzyme capture by an antibody layer immobilised on a planar gold electrode sensor. Gold/Ti-on-glass substrates have been used, in a 2 electrode configuration, with antibodies immobilised on the working electrode. Microfluidic structures have been fabricated by a CO2 laser, in 25 mum thick pressure sensitive adhesive (PSA), on a PMMA lid, and the structure bonded on top of the planar sensor. Microfluidic blood/serum delivery has been investigated using a visualisation dye. Some flow problems are observed if the sensor is exposed to air for several days, suggesting that flow channel nanopillars and hermetic encapsulation may be required to guarantee flow properties in commercially produced modules. Work is ongoing to characterise the impedimetric signal changes for myoglobin capture by antimyoglobin, using these sensors. Fifty micron thick PSA, incorporating a robust spacer layer, will be used to give better definition of channel walls.

An impedimetric sensor for monitoring the growth of Staphylococcus epidermidis.

There is a need for accurate, reliable methods of detecting bacteria for a range of applications. One organism that is commonly found in urinary catheter infections is Staphylococcus epidermidis. Current methods to determine the presence of an infection require the removal of catheters. An alternative approach may be the use of in vivo sensing for bacterial/biofilm detection. This work investigates electrical impedance spectroscopy to detect the growth of Staphylococcus epidermidis RP62A on gold electrodes fabricated on a flexible substrate. Impedance spectra measured during biofilm formation on the electrode surface showed an increase in charge transfer resistance (RCT) with time.

Experimental determination of compound action potential direction and propagation velocity from multi-electrode nerve cuffs.

Information extracted from whole-nerve electroneurograms, recorded using electrode cuffs, can provide signals to neuroprostheses. However, the amount of information that can be extracted from a single tripole is limited. This communication demonstrates how previously unavailable information about the direction of action potential propagation and velocity can be obtained using a multi-electrode cuff and that the arrangement acts as a velocity-selective filter. Results from in vitro experiments on frog nerves are presented.

Wearable and implantable monitoring systems: 10 years experience at University of Ulster.

Over the past 10 years or more, NIBEC and, more recently, Sensor Technology and Devices Ltd have been at the forefront of developments in sensor-related technologies which underpin a wide range of monitoring systems presently commercialised by leading multinationals. Systems developed/ commercialised include astronaut-monitoring arrays, cardiac mapping harnesses, ECG electrodes, Telemedicine systems and implant sensor arrays. This paper presents the main developments in this area and discusses outstanding issues for future research.

Composite carbon paste biosensor for phenolic derivatives based on in situ electrogenerated polypyrrole binder.

Amperometric biosensors based on new composite carbon paste (CPE) electrodes have been designed for the determination of phenolic compounds. The composite CPEs were prepared by in situ generation of polypyrrole (PPy) within a paste containing the enzyme polyphenol oxidase (PPO). The best paste composition (enzyme/pyrrole monomer/carbon particles/Nujol) was determined for a model enzyme, glucose oxidase, according to the enzymatic activity of the resulting electrodes and to the enzyme leakage from the paste during storage in phosphate buffer. The in situ electrogenerated PPy enables improvement in enzyme immobilization within the paste since practically no enzyme was lost in solution after 72 h of immersion. Moreover, the enzyme activity remains particularly stable under storage since the biocomposite structure maintains 80% of its activity after 1-month storage. Following the optimization of the paste composition, PPO-based carbon paste biosensors were prepared and presented excellent analytical properties toward catechol detection with a sensitivity of 4.7 A M(-1) cm(-2) and a response time lower than 20 s. The resulting biosensors were finally applied to the determination of epicatechin and ferulic acid as flavonol and polyphenol model, respectively.

Sauer's non-linear voltage division.

The non-linearity of the electrode-tissue interface impedance gives rise to harmonics and thus degrades the accuracy of impedance measurements. Also, electrodes are often driven into the non-linear range of their polarisation impedance. This is particularly true in clinical applications. Techniques to correct for electrode effects are usually based on linear electrode impedance data. However, these data can be very different from the non-linear values needed. Non-linear electrode data suggested a model based on simple assumptions. It is useful in predicting the frequency dependence of non-linear effects from linear properties. Sauer's treatment is a first attempt to provide a more general and rigorous basis for modelling the non-linear state. The paper reports Sauer's treatment of the non-linear case and points out its limitations. The paper considers Sauer's treatment of a series arrangement of two impedances. The tissue impedance is represented by a linear voltage-current characteristic. The interface impedance is represented by a Volterra expansion. The response of this network to periodic signals is calculated up to the second-order term of the series expansion. The resultant, time-dependent current is found to contain a DC term (rectification), as well as frequency-dependent terms. Sauer's treatment assumes a voltage clamp across the impedances and neglects higher-order terms in the series expansion. As a consequence, it fails adequately to represent some experimentally observed phenomena. It is therefore suggested that Sauer's expressions for the voltage divider should be combined with the non-linear treatments previously published by the co-authors. Although Sauer's work on the non-linear voltage divider was originally applied to the study of the non-linear behaviour of the electrode-electrolyte interface and biological tissues, it is stressed, however, that the work is applicable to a wide range of research areas.

Harmonic analysis of low-frequency bioelectrode behavior.

This paper concerns the modeling and interpretation of harmonics observed as a result of the nonlinear electrical properties of biomedical electrode/electrolyte interfaces. The higher order harmonics have been calculated assuming that the nonlinearity of the interfacial impedance is dominated at low frequencies by the nonlinear faradaic charge transfer resistance. The harmonic distribution in the output signal is compared between 1) the author's theoretical model based on the Butler-Volmer equation and 2) Schwan's empirical model and results. The influence of different parameters such as the number of electrons involved in the faradaic reaction and the transfer coefficient was investigated in order to physically interpret the experimental results. A good agreement was found between the authors' model and some of the experimental data previously reported in the literature. Further, potentially productive areas of research have been identified.