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  • Open access
  • 12 Reads
On the use of Deep Learning Decompositions and Physiological Measurements for the Prediction of Preterm Pregnancies in a Cohort of Patients in Active Labour

Preterm pregnancies are one of the leading causes of morbidity and mortality amongst children under the age of 5. This is a global issue and has been identified as an area requiring active research. The emphasis now is to identify and develop methods of predicting the likelihood of preterm birth. Accurately predicting the potential of a preterm birth helps to develop and improve proactive care and treatment strategies for this vulnerable population.

This paper uses physiological data from a group of patients in active labour. The dataset contains information about foetal heart rate (FHR) and maternal heart rate (MHR) for all patients and Electro hysterogram (EHG) recordings for the measurement of uterine contractions. For the physiological data analysis and associated signal processing, we utilise Deep Wavelet Scattering (DWS). This is an unsupervised decomposition and feature extraction method combining characteristics from Deep Learning Convolutions, as well as the classical Wavelet Transform, to observe and investigate the extent to which active preterm labour can be accurately identified from an acquired physiological signal. Additional machine learning algorithms are tested on the acquired physiological data to allow for the identification of optimal model architecture for this specific physiological data.

  • Open access
  • 183 Reads
An IoT Braille display towards assisting visually impaired students in Mexico

According to the World Health Organization, 2.2 billion people have some vision impairment globally (WHO 2021). The impairment prevalence in low and middle-income areas, like Mexico and Latin America, is estimated to be 400% higher than in high-income regions. In addition, the blind and vision impairment population faces severe social and academic exclusion. For instance, children can undergo poor motor, language, and cognitive evolution, bringing lower levels of educational success.
Braille script represents a language's characters in a rectangular arrangement of raised dots so that blind people can read the symbols and obtain written knowledge through the touch sense. Braille characters are generally printed in books or on commonly used surfaces such as ATMs. However, printing requires many resources since it must be done for each occasion. This is why electronic braille displays were created that connect to a computer or smartphone and tactilely represent the text shown on the screen. Unfortunately for people in developing countries, it is not easy to access this technology since its cost is very high.
Hence, this paper shows the design and development of a one-character refreshable braille display that is affordable and easy to use through the Internet of Things (IoT) technology. The MQTT protocol was used to communicate the digital text and convert it into physical braille text; the MQTT is a well-known messaging protocol for the IoT. The device was designed with electromagnetic push-pull solenoids connected to an ESP-32 microcontroller card. Each solenoid represents a dot of the braille character through its vertical movement, which allows blind people to read from the device by touch. Reading is essential to acquire knowledge by allowing an affordable form of reading based on braille, a handy tool for teaching and training blind and visually impaired people can be reached.

  • Open access
  • 21 Reads
Refractive index sensing in a disposable micro-channel provided with integrated reflectors based on laser beam shift

In this work, we present a compact micro-opto-fluidic sensing platform for the measurement of volumetric refractive index (RI) variations of ultra-low volumes of fluids with respect to a reference liquid. In the instrumental configuration, we employed a disposable plastic micro-channel, which was customized with integrated back and front Aluminum reflectors, deposited by sputtering. The presence of the double metallization is exploited to create a zig-zag guiding path for the radiation provided by a semiconductor laser diode, so that light crosses the fluid under test multiple times before reaching a 1-D Position Sensitive Detector (PSD). According to Snell law, when fluids with different RI indices fill the channel, the radiation is deflected at different angles and the output beam shifts along the channel surface. RI variations are monitored by measuring the position of the output light spot on the surface of the PSD. To validate the results, a theoretical model based on ray optics was developed to study the propagation of the radiation travelling through the fluidic channel. Experimental results showed a beam displacement per RI unit up to 3234 μm/RIU, in agreement with the prediction of the analytical model. The proposed sensing method is label-free, contactless, non-invasive and biologically safe. Moreover, the micro-opto-fluidic sensing platform could be exploited in a wide range of applications, ranging from biology to medicine to agri-food industry.

  • Open access
  • 22 Reads
Quinoline-based hydrazone derivative as a biocide chemosensor: synthesis and sensing studies

Tributyltin (TBT) is an organic biocide used on antifouling paints to avoid biofouling on boats and submersed structures. It was found that TBT was toxic to a variety of aquatic organisms, and it was banned by the Rotterdam Convention, in 1998. TBT sensing is still an important issue since it is still affecting aquatic environments, besides the fact that some countries did not sign the convention and are still using it. Current TBT monitoring methods are based on sampling and laboratory analysis, which is expensive, time-consuming, and require expert users. Therefore, a new simple and fast TBT sensing method would be of great interest.

In this work, a new quinoline-based hydrazone derivative was synthesized by a condensation reaction in 67 % yield. The new compound was characterized by the usual spectroscopic and spectrometric techniques. The preliminary chemosensory study of the hydrazone derivative in the presence of TBT in acetonitrile solution, resulted in a color change from colorless to red and the appearance of fluorescence. This interaction was confirmed by spectrophotometric and spectrofluorimetric titrations which revealed that 17 equiv. of TBT led to a maximum optical signal in terms of fluorescence intensity and absorbance.

  • Open access
  • 22 Reads
3D porous plasmonic nanoarchitectures for SERS-based chemical sensing

Achieving superior results in chemical and biological sensing using plasmon-enhanced stimulated Raman scattering requires (i) the creation of a wide variety of hot spots and (ii) the formation of an efficient way to deliver target molecules to places with intense electromagnetic fields. Therefore, for advanced SERS-sensing we developed porous three-dimensional (3D) wedge-shaped nanoarchitectures based on close-packed multilayers of gold nanoparticles (Au NPs) with porosity 38-70% and nanoparticle sizes of 25–7 nm; the structures were produced by pulsed laser deposition in an argon atmosphere. Designed SERS substrates are characterized by 3D spatially distributed high-density pores with a size of 30–2 nm (plasmonic hot spots). The presence of 3D pores in the structure leads to an increase in the total surface area and allows the analyte molecules to diffuse deep into the materials, which ensures the collection of more molecules.

In this work, we demonstrate the effective enhancement of the Raman scattering of Rhodamine 6G molecules (within the concentration range 10-5 - 1010M) under resonant excitation by radiation λex=488.0, 514.5 nm, which is outside the region of surface plasmon resonance (SPR) excitation in 3D Au nanostructures (λSPR= 570-720 nm). Raman enhancement mechanisms include a combination of several effects: molecular resonance; the electromagnetic effect; and non-resonant chemical amplification. Electromagnetic amplification dominates in the areas of hot spots, located mainly within the internal pores of the material; excitation of the gold nanoparticles surrounding the pore occurs as a result of re-emission (luminescence) of the laser excitation by rhodamine 6G molecules as a result of the optical frequency down-conversion process. An analysis of the dependence of the Raman intensity on the structural parameters of the porous layers of Au NPs made it possible to establish that the greatest signal amplification is observed for the material with the highest density of hot spots.

  • Open access
  • 29 Reads
Validation of a low cost sensor for kinematic assessment in cyclists
Published: 01 November 2022 by MDPI in 9th International Electronic Conference on Sensors and Applications session Posters

Knowing the relationship between the movements of the ankle, knee, and hip joints is presented as necessary as it could help us to better understand the mechanisms of power production and how the adjustment of these different variables can condition sports performance or comfort in cycling (1,2).

Due to this need, biomechanics applied to cycling has undergone great evolution in recent decades, both in the analysis techniques and in the technological systems used. But the majority of the techniques used until today start from an important limitation, because isolate the cyclist from the ecological context of their sports practice and leading them to develop their capabilities under laboratory conditions.

Recently, the advancement in the technology of different wearables has allowed us to capture and analyze human movement in an ecological way with hardly any interference in it (3,4).

The use of inertial measurement sensors (IMUs), in the search for a more ecological measure, is spreading among sports professionals with the aim of improving the sports performance of cyclists. The kinematic evaluation using the IMU sensors has become popular.

These new devices are promising and open a wide range of possibilities, and although there are already several studies that have demonstrated the strength of IMU technology to measure joint kinematics, the validity and reliability of each device must be individually contrasted.

The present study aimed to evaluate the reliability and validity of a novel IMUs Sensor by measuring the angular kinematics of the lower extremities in the sagittal plane during pedaling at different intensities compared to a gold-standard motion capture camera system (OptiTrack, Natural Point, Inc., Corvallis, OR, USA).

Twenty-four elite cyclists recruited from national and international cycling teams performed two 6-min cycles of cycling on a cycle ergometer at two different intensities (first ventilatory threshold (VT1) and second ventilatory threshold (VT2)) in random order, with a 5 min rest between intensity conditions. The reliability and validity of the novel IMUs Sensor versus the motion capture system were evaluated.

Both systems showed high validity and were consistently excellent in foot angular range Q1 (FAR (Q1)) and foot angular range (FAR) (ICC-VT1 between 0.91 and 0.95 and ICC-VT2 between 0.88 and 0.97), while the variables leg angular range (LAR) and pelvic angle showed a modest validity (ICC-VT1 from 0.52 to 0.71 and ICC-VT2 between 0.61 and 0.67). Compared with Optitrack, the novel IMUs Sensor overestimated all the variables, especially the LAR and pelvic angle values, in a range between 12 and 15º.

This novel IMUs Sensors a reliable and valid tool for analyzing the ranges of motion of the cyclist’s lower limbs in the sagittal plane, especially for the variables FAR (Q1) and FAR. However, its systematic error for FAR and Pelvic Angle values must be considered in sports performance analysis.

  1. Vrints, J.; Koninckx, E.; Van Leemputte, M.; Jonkers, Y.I. The Effect of Saddle Position on Maximal Power Output and Moment Generating Capacity of Lower Limb Muscles during Isokinetic Cycling. J. Appl. Biomech. 2011, 27, 1–7. [CrossRef]
  2. Quesada, J.I.P.; Kerr, Z.Y.; Bertucci, W.M.; Carpes, Y.F.P. The association of bike fitting with injury, comfort, and pain during cycling: An international retrospective survey. Eur. J. Sport Sci. 2018, 19, 842–849
  3. Marin, F.; Fradet, L.; Lepetit, K.; Hansen, C.; Ben Mansour, Y.K. Inertial measurement unit in biomechanics and sport biomechanics: Past, present, future. In Proceedings of the ISBS-Conference Proceedings Archive, Poitiers, France, 29 June–3 July 2015.
  4. Camomilla, V.; Bergamini, E.; Fantozzi, S.; Vannozzi, Y.G. Trends Supporting the In-Field Use of Wearable Inertial Sensors for Sport Performance Evaluation: A Systematic Review. Sensors 2018, 18, 873.
  5. Kobsar, D.; Charlton, J.M.; Tse, C.T.F.; Esculier, J.-F.; Graffos, A.; Krowchuk, N.M.; Thatcher, D.; Hunt, M.A. Validity and reliability of wearable inertial sensors in healthy adult walking: A systematic review and meta-analysis. J. Neuroeng. Rehabil. 2020, 17, 62.
  6. Poitras, I.; Dupuis, F.; Bielmann, M.; Campeau-Lecours, A.; Mercier, C.; Bouyer, L.; Roy, J.-S. Validity and Reliability of Wearable Sensors for Joint Angle Estimation: A Systematic Review. Sensors 2019, 19, 1555.
  • Open access
  • 40 Reads
Instrumented Treadmill with an Accelerometry System: a Valid and Reliable Tool for Running Analysis
Published: 01 November 2022 by MDPI in 9th International Electronic Conference on Sensors and Applications session Posters

Concurrent biofeedback has been demonstrated to be an effective strategy to reduce running-related injuries (RRI) [1,3,5]. The majority of these RRI are overuse injuries related to impact accelerations [2,4]. However, information regarding impact accelerations is not accessible to the entire population since it requires an accelerometry system. The objective of this study was to investigate the validity and reliability of a new accelerometry system placed directly into the treadmill (AccTrea), and compare it to the traditional system placed directly on the athlete’s body (AccAthl). Thirty recreational athletes with no history of lower body injuries performed two running tests on different days. They ran for 5 min at 10 km/h and 0% slope and acceleration impacts and spatio-temporal parameters were collected in two sets of 10 s during the las minute taken in each measurement session. The first session intended to assess the validity of an AccTrea versus an AccAthl, and the second session intended to test the reliability. The results showed that AccTrea is a valid and reliable tool for measuring spatio-temporal parameters like step length (validity intraclass correlation coefficient (ICC) = 0.94; reliability ICC = 0.92), step time (validity ICC = 0.95; reliability ICC = 0.96), and step frequency (validity ICC = 0.95; reliability ICC = 0.96) during running. Peak acceleration impact variables manifested a high reliability for both left (reliability ICC = 0.88) and right legs (reliability ICC = 0.85), and peak impact asymmetry demonstrated a modest validity (ICC = 0.55). The valid and reliable results, make the AccTrea system an appropriate tool to inform athletes about their running mechanics, bringing the laboratory data closer to the running community.

  1. Crowell, H.P.; Davis, I.S. Gait retraining to reduce lower extremity loading in runners. Clin. Biomech. 2011, 26, 78–83.
  2. Derrick, T.R.; Dereu, D.; McLean, S.P. Impacts and kinematic adjustments during an exhaustive run. Med. Sci. Sports Exerc. 2002, 34, 998–1002.
  3. Eriksson, M.; Halvorsen, K.A.; Gullstrand, L. Immediate effect of visual and auditory feedback to control the running mechanics of well-trained athletes. J. Sports Sci. 2011, 29, 253–262.
  4. Mizrahi, J.; Verbitsky, O.; Isakov, E.; Daily, D. Effect of fatigue on leg kinematics and impact acceleration in long distance running. Hum. Mov. Sci. 2000, 19, 139–151.
  5. Wood, C.M.; Kipp, K. Use of audio biofeedback to reduce tibial impact accelerations during running. J. Biomech. 2014, 47, 1739–1741.

  • Open access
  • 29 Reads
Advanced Quartz Microbalance Sensors for Gas-Phase Applications: Effect of Adsorbate on Friction at Transducer-Nanoparticle Interface

New sensitive architectures built on soft surface architectures or nano-sized blocks also require a rethinking of the principles of operation of traditional physical recording methods. One of these types includes sensors based on Quartz Crystal Microbalance (QCM). Today, there is no doubt that in many scenarios of molecular adsorption, both frequency change and the dissipation is not primarily determined by the adsorbate itself, but rather by the link by which it is bound to the transducer.

In this abstract, we report an experimental study of tuning interfacial friction for latex nanoparticles (NP, LB1 (Sigma-Aldrich),100 nm in diameter, the surface is very hydrophobic in character) adsorbed on planar silver (hydrophilic)electrodes of QCM transducers by gaseous analytes (saturated water vapor as a case in point).Measurements were performed for both stock LB1 NP and those applied mixed with 0.2% TWEEN-20. Due to its surfactant nature, TWEEN-20 enhances the attraction of nanoparticles to the surface but prevent their aggregation. For such coatings, the classical Sauerbrey behavior was observed, when the adsorption of the analyte leads to a decrease in the resonant frequency of the sensor.

A qualitatively different response behavior was observed for native LB1 NP without the addition of a surfactant. The initial decrease in frequency due to water adsorption was replaced by a sharp increase in frequency up to values greater than the initial ones; with further exposure, the decrease and increase in frequency replace each other. The observed anti- Sauerbrey behavior is considered as a possibility of NP rolling, sliding (the NP purely skids on a surface) and slipping (the object also has some angular motion) as well as change of surface coating viscosity.

The possibility of a gaseous analyte not only to change the QCM loading, but also the features of the mechanical behavior of the mass associated with the surface through a local change in friction in the contact area, opens the way to the creation of highly selective sensors, the response of which to a given analyte has a large value of the opposite sign.

  • Open access
  • 17 Reads
Distributed remote-controlled sensor network for monitoring complex gas environments based on intelligent gas analyzers

The increasing complexity of modern industrial production, the potential threats of chemical or biological pollution due to accidents, transport incidents or terrorist attacks require continuous monitoring of changes occurring in complex multicomponent environments (CME) in order to timely eliminate their consequences. To make adequate decisions in such a short time, it is necessary to have the most complete information about a wide range of potential xenobiotics within the controlled area. In this study, such an important scientific and practical problem is solved by forming a unique “chemical image of the environment” using an intelligent gas analyzer based on a cross-reactive array of chemical sensors using piezoelectric elements of a quartz crystal microbalance (QCM) as physical transducers. The originality of this work lies in the formation of a network of such intelligent analyzers connected by means of telecommunication protocols for the operational control of the perimeter of a protected and\or dangerous zone by monitoring the gaseous environment.

The system includes (i) a central station with an expert decision-making system, (ii) several sensor modules, (iii) a local power supply system, and (iv) devices for information exchange between the central station and sensor modules. The sensor module is based on an 8 channels analyzer using the electronic nose concept (Gestalt-like perception of CME by virtual coding with so-called chemical images). The selectivity profile of the sensor array is determined by a set of sensitive layers deposited on the electrodes of the QCM transducers.

  • Open access
  • 8 Reads
VNetOS: Virtualised Distributed and Parallel Sensor Network Operating Environment for the IoT and SHM

Dealing with distributed and parallel computing in strong heterogeneous environments, e.g., distributed sensor networks, is still a challenge on algorithmic, communication, and application level. Heterogeneity is related to different computer and network (communication) architectures. Virtualisation can hide and unify heterogeneity. Beside inter-process communication and synchronisation the unified access and monitoring of computing nodes (devices, computers, processors) is required to handle distributed and parallel systems in a comfortable and easy-to-access manner. Especially in education the access and control of a large set of computing nodes is difficult and lowers the learning curve significantly. In this work, a unified distributed and parallel framework and Web tools are introduced using Virtual Machines (VM) and Web browsers to control them. The framework enables the control, monitoring, and study of distributed-parallel systems, especially addressing sensor networks and IoT networks. Nodes can be arranged in a graphical drawing world or script-based. Virtual network nodes are assigned to VM instances that can be created inside the browser using Web worker processes or can be attached to externally running VM instances via a Web control API. New VM instances or processes can be started and controlled instantly. The graphical UI provides access to the nodes, programming editors, and monitor shells. The VMs can be generic, but in this work there is a focus on JavaScript, Lua, and an agent platform.