Wireless ECG and cardiac monitoring systems: State of the art, available commercial devices and useful electronic components

Abstract Wireless ElectroCardioGram (ECG) systems are employed in manifold application fields: tele-monitoring, sport applications, support to ageing people at home, fetal ECG, wearable devices and ambulatory monitoring. The presence of cables often hinders user’s free movements, alongside clinicians’ routine operations. Therefore, wireless ECG systems are desirable. This paper aims at reviewing the solutions described in the literature, besides commercially available devices and electronic components useful to setup laboratory prototypes. Several systems have been developed, different in terms of the adopted technology; when approaching the development of a wireless ECG system, some import…

On the Measurement and Prediction of the Out-of-Plane Displacement Surrounding Cold-Expanded Holes

Experimental measurements of the out-of-plane displacement surrounding cold-expanded holes in a 6082-T6 aluminum alloy were made with a 3D optical scanner using the technique of the encoded light-pattern projection in white light. The measured surface profiles have shown the thickness discontinuity along the hole edge due to the effect of the split in the sleeve. An analytical–numerical solution of the out-of-plane displacement is presented based on existing analytical models. Thus, the results given by the analytical model were then compared with the experimental data and with a finite element (FE) model that simulates the cold-expansion process. The location of the elastic–plastic boundar…

Impiego di tecniche di misura DIC per lo studio di sistemi di sintesi ortopedici

Nel presente lavoro si esamina la possibilità di impiego di tecniche di correlazione digitale di immagini in configurazione stereoscopica per la valutazione sperimentale in-vitro del campo tridimensionale di spostamento e deformazione generato sottocarico sull’osso trattato con un impianto di sintesi intramidollare. L’inserimento di una rima di frattura praticata sulla diafisi media dell’osso sintetico, ha consentito di studiare il differente comportamento nelle due condizioni limite del decorso clinico a seguito del trattamento chirurgico di impianto. I risultati preliminari riportati nel lavoro dimostrano l’efficacia dell’approccio proposto, che consente di valutare sperimentalmente lo st…

Wooden panel paintings investigation: An air-coupled ultrasonic imaging approach

In this paper, a method for the study of wooden panel paintings using air-coupled acoustical imaging is presented. In order to evaluate the advantages of the technique, several samples were made to mimic panel paintings along with their typical defects. These specimens were tested by means of both single-sided and through-transmission techniques using planar transducers. Image data were processed by means of a two-dimensional (2-D)-fast Fourier transform-based algorithm to increase the S/N ratio and 2-D representations (C-scans) were generated. The simulated defects were imaged using both configurations. Investigations were undertaken on four antique paintings from a private collection. The…

Modelling cardiac mechanics of left ventricular noncompaction

Left ventricular noncompaction (LVNC) can be defined as a cardiomyopathy characterised by a pattern of prominent trabecular structure and deep intertrabecular recesses, that is thought to be caused by an arrest of normal endomyocardial morphogenesis. Using patient-specific computational modelling, we assessed the cardiac mechanics of five patients with LVNC and compared myocardial stress and pump performance to those of healthy controls. Findings shown that patients with LVNC have impaired left ventricular (LV) function, making it possible that the lack of fibre shortening of noncompacted layer can determine poor heart function. Pronounced end-systolic wall stress on left ventricular wall o…

HYDROGELS WITH ORDER POROSITY AT THE MESO-SCALE FOR SENSING

A Direction/Orientation-Based Method for Shape Measurement by Shadow MoirÉ

In this paper, a methodology to process fringe patterns is presented. The core of the signal processing technique is the use of the direction information, which is a modulo quantity that locally indicates the direction along which fringes grow at a maximum rate. By using this information, it was possible to perform adaptive and direction/orientation-based operations on fringe images to remove unwanted effects (mainly distortions at the image borders), to enhance the contrast, and to extract the phase information encoded. The method has been applied on shadow-moire interferograms with carrier fringes in order to measure the surface of small objects. The developed algorithm allows processing …

Stiffness and Reinforcement Effect of electrical Resistance Strain Gauges

:  The increasing use of low-modulus materials, on which the reinforcement effect of the electrical resistance strain gauge is not negligible, has re-opened the research interest into this issue. This study deals with the evaluation of stiffness, and of the strain gauge Young's modulus involved in the estimation of both the global and the local reinforcement effect; the relationship between the strain gauge stiffness and the local reinforcement effect is also analysed. In particular, the experimental technique used to determine the stiffness of some commercial strain gauges is described. The results show that the strain gauge stiffness alone does not permit an accurate evaluation of the loc…

Analysis of the accuracy of fiber-optic strain transducers installed by using composite smart patches

The aim of this work is to investigate the accuracy of fiber-optic strain transducer related to the incomplete load transmission that can occur on composite smart patches used as base support for the installation of such transducer, commonly used for structural monitoring of concrete elements. In detail, since the dimensions of the transducer are generally very small compared to those of the structural element being monitored, attention is given not to the global reinforcement effect, which occurs when the transducer alters the entire strain field of the transversal section of the monitored element, but rather to the so-called local reinforcement effect, which is due to an incomplete load …

Thermoelastic Stress Analysis by Means of a Standard Thermocamera and a 2D-Fft Based Lock-In Technique

The thermoelastic effect in a generic orthotropic body under adiabatic and linear elastic stress conditions induces small and reversible temperature changes that can be correlated with the stress field by means of linear relationships. Infrared techniques are mainly used to measure temperature changes on the component surface [1], while adiabatic conditions are generally achieved by applying cyclic loads above a threshold frequency. The resolution resulting from implementing a Thermoelastic Stress Analysis (TSA) technique is a combination of the infrared acquiring system resolution and of the signal post-processing procedure. State of the art infrared detectors have NETD (Noise Equivalent T…

Impact Force Identification and Location on Isotropic and Composite Panels.

Steam sterilization processes affect the stability of clinical thermometers: Thermistor and prototypal FBG probe comparison

Abstract Temperature is one of the most frequently measured physical quantities in clinical environment and a good biomarker of illness. The need for reusable probes, which have to be sterilized to prevent infections, requires the metrological qualification of thermometer probes in response to ageing effects induced by several sterilization processes. In this study, we investigated the effect of repeated sterilizations on both a commonly-used autoclavable thermistor probe and a prototypal Fiber Bragg Gratings (FBG) probe for temperature measurements. Findings highlighted a greater reliability of the proposed FBG probe than the commercial thermistor. Specifically, the FBG probe was able to w…

A NOVEL BI-DIMENSIONAL FOURIER TRANSFORM METHOD TO SURFACE RECONSTRUCTION BY SHADOW MOIRÉ

A NEO APPLICATION OF REVERSE ENGINEERING BASED ON THE PROJECTION MOIRé TECHNIQUE

Wooden Surface Investigation: an Optical Approach Based on Shadow Moiré

The interest in the mechanical behaviour of wood is a very important task due to the increasing role played by wood structures in modern architecture as well as its applicability in restoration of ancient buildings. The behaviour of wooden surfaces experiencing variable humidity conditions is of great importance both with concern to performances of wooden building’s structures and to ensure correct restoration and conservation of art works like wooden sculptures and panel paintings [1]. In literature there are only a few studies dealing with the influence of moisture on the physical properties of wood [1,2]. The characterization of wooden behaviour related to changes in the humidity level c…

Ethanol vapor optical sensors based on polystyrene opals infiltrated with hydrogel

METODOLOGIA PER IL RILIEVO SIMULTANEO DELL’USURA DIFFUSA E LOCALIZZATA IN CUSCINETTI A ROTOLAMENTO

A direction/orientation-based method for shape measurement by shadow moiré

In this paper, a methodology to process fringe patterns is presented. The core of the signal processing technique is the use of the direction information, which is a modulo 2 pi quantity that locally indicates the direction along which fringes grow at a maximum rate. By using this information, it was possible to perform adaptive and direction/orientation-based operations on fringe images to remove unwanted effects (mainly distortions at the image borders), to enhance the contrast, and to extract the phase information encoded. The method has been applied on shadow-moire interferograms with carrier fringes in order to measure the surface of small objects. The developed algorithm allows proces…

AIR-COUPLED ACOUSTICAL IMAGING NDE FOR ART OBJECT STUDY

ELASTIC WAVE CHARACTERIZATION ALONG DAVIES’ BAR

Development of a low-cost piezo film-based knock sensor

It is well known that spark advance is a key parameter in spark ignition engine management. Increasing fuel cost and emission regulation strictness require a higher engine efficiency, which can be improved by an accurate regulation of the spark advance. Under high load conditions, an optimal spark advance choice leads the engine to run next to the knock limit, so the management and control system needs to be equipped with a knock sensor in order to preserve the engine from damage. The authors developed a low-cost knock sensor whose sensing element is a thin washer of polyvinylidine fluoride (PVDF), a fluoropolymer characterized by a great piezoelectric e ect if polarized. The sensor has be…

Opals infiltrated with a stimuli-responsive hydrogel for ethanol vapor sensing

We report on a novel class of optical materials for ethanol vapor sensing, based on polystyrene opals infiltrated with an innovative stimuli responsive hydrogel. We describe the fabrication process of the bare polystyrene opals and their subsequent infiltration. The optical characterization of the photonic crystal templates was performed to prove the good quality of the samples. Measurements on the infiltrated opals showed that the transmission spectra in the visible range strongly change at varying concentrations of ethanol vapor. The fabricated structures show a linear optical response in the visible range, for high values of ethanol concentration.

High-velocity Impact Location on Aircraft panels Using Macro-fiber Composite piezoelectric Rosettes

In this article, an approach based on an array of macro-fiber composite (MFC) transducers arranged as rosettes is proposed for high-velocity impact location on isotropic and composite aircraft panels. Each rosette, using the directivity behavior of three MFC sensors, provides the direction of an incoming wave generated by the impact source as a principal strain angle. A minimum of two rosettes is sufficient to determine the impact location by intersecting the wave directions. The piezoelectric rosette approach is easier to implement than the well-known time-of-flight-based triangulation of acoustic emissions because it does not require knowledge of the wave speed in the material. Hence, th…

Hydrogel films engineered in a mesoscopically ordered structure and responsive to ethanol vapors

Abstract Responsive hydrogels filling the interstitial spaces of photonic crystals can form mesoscopically structured materials, which exhibit reversible shifts in the Bragg diffracted light as a response of environmental changes. These materials can be used to generate chemical or biochemical sensors. The present work reports on the synthesis and characterization of ethanol responsive hydrogels that can be used in the design of novel breathalyzers. The dynamic mechanical behavior of the macroscopic hydrogels and their swelling features in the presence of different liquids or vapors have been investigated to orientate the choice of the best responsive material and curing process. The swelli…

VALUTAZIONE DEGLI EFFETTI DI CURVATURA E SCORRIMENTO LOCALE NELLE MISURE DI DEFORMAZIONE MEDIANTE SENSORI FBG

Shear stress alterations in the celiac trunk of patients with a continuous-flow left ventricular assist device as shown by in-silico and in-vitro flow analyses

Background The use of left ventricular assist devices (LVADs) to treat advanced cardiac heart failure is constantly increasing, although this device leads to high risk for gastrointestinal bleeding. Methods Using in-silico flow analysis, we quantified hemodynamic alterations due to continuous-flow LVAD (HeartWare, Inc., Framingham, MA) in the celiac trunk and major branches of the abdominal aorta, and then explored the relationship between wall shear stress (WSS) and celiac trunk orientation. To assess outflow from the aortic branch, a 3-dimensional-printed patient-specific model of the celiac trunk reconstructed from an LVAD-supported patient was used to estimate echocardiographic outflow …

Simultaneous measurement of temperature and strain in glass fiber/epoxy composites by embedded fiber optic sensors: I. Cure monitoring

In this paper (Part I) the use of fiber optic sensors for real-time monitoring of the cure kinetics of GFRP composites is explored. The proposed sensing system allows the simultaneous measurement of both temperature and strain by monitoring the change in reflected wavelength from two coupled fiber Bragg grating (FBG) sensors that have been embedded into the composite laminate. Instrumented GFRP laminates with 12, 18 and 24 reinforcing plies, respectively, were prepared by means of the vacuum bagging technique. Samples were cured in a thermally controlled oven at 80 degrees C and 30 kPa for 240 min (isothermal stage) and then cooled down to ambient temperature by turning off the heating sour…

Sensori in fibra ottica con reticolo di Bragg: grandezze di influenza, accuratezza metrologica, campi di applicazione

Optical sensors for ethanol vapor based on polystyrene opals infiltrated with hydrogel

This paper deals with a novel class of optical sensors for ethanol vapor, based on polystyrene opals infiltrated with a hydrogel sensitive to ethanol. Optical characterization of such opals has been performed, proving their effectiveness as sensors

CARATTERIZZAZIONE DELL’ATTRITO SU COMPONENTI PER APPLICAZIONI ORTODONTICHE MEDIANTE UN SIMULATORE “IN VITRO”

La diffusione delle tecniche a basso attrito (low friction) nell’ambito di terapie ortodontiche per lo spostamento di un dente mediante applicazione di una forza debole (0.5 – 0.7 N) o media (0.7-2.0 N) ha spinto la ricerca del settore odontoiatrico verso lo studio delle forze di attrito nel moto tra archetto ortodontico (archwire) e attacchi ortodontici (brackets). L’esame della letteratura ha mostrato alcuni approcci molto semplificati alla misura dell’attrito, con configurazioni piane, mediante simulazioni poco aderenti a quanto accade nel corso di una reale terapia ortodontica. Il presente lavoro si prefigge uno studio preliminare del fenomeno mediante caratterizzazione della forza di a…

VERIFICA DELL’ATTECCHIMENTO DEGLI INNESTI-TALEA DI VITE DOPO LA FORZATURA MEDIANTE TECNICHE TERMOGRAFICHE E MECCANICHE

Grafting is an important technique for getting good yields in plant multiplication. Understanding the success of the graft after the incubation room is important to the evaluation of the suitable grafting for the open field (nursery). Successful grafting in vines requires the development of a functional vascular system between the scion and the rootstock. The graft compatibility and its augmentation depend upon various natural factors like environment, weather, soil conditions and protective measures etc. The present study examines the capability of thermography, mechanical and electrical techniques to assess the graft quality and successful of Vitis vinifera after the incubation room. Afte…

Computational modeling of bicuspid aortopathy: Towards personalized risk strategies.

This paper describes current advances on the application of in-silico for the understanding of bicuspid aortopathy and future perspectives of this technology on routine clinical care. This includes the impact that artificial intelligence can provide to develop computer-based clinical decision support system and that wearable sensors can offer to remotely monitor high-risk bicuspid aortic valve (BAV) patients. First, we discussed the benefit of computational modeling by providing tangible examples of in-silico software products based on computational fluid-dynamic (CFD) and finite-element method (FEM) that are currently transforming the way we diagnose and treat cardiovascular diseases. Then…

Particle image velocimetry study of the celiac trunk hemodynamic induced by continuous-flow left ventricular assist device

Abstract Whereas left ventricular assist device (LVAD) is the gold-standard therapy for patients with heart failure, gastrointestinal bleeding is one of the most common complications. LVAD implantation may remarkably impact aortic hemodynamics so that experimental and computational flow analyses can be used to study the disease mechanisms. Here we present an experimentally-calibrated computational model of the celiac trunk hemodynamic of a LVAD-supported patient who experienced bleeding after device implantation. Specifically, both particle image velocimetry (PIV) and echocardiography were used to measure and compare flow distributions in each branch of a phantom model of the patient abdomi…

Forza - CAP 16 di VALLASCAS R. Fondamenti di misure meccaniche e termiche Grandezze statiche e sistemi

Periodically nanostructured hydrogels for ethanol vapors sensing

Chemical sensing using optics has been under extensive research all over the world during last decades and many optical chemical sensors are nowadays finding increasing applications in industry, environmental monitoring, medicine, biomedicine and chemical analysis. These optical sensors can be based on various optical principles, such as absorbance, reflectance or transmittance, luminescence and fluorescence, covering different regions of the spectrum (UV, visible, IR, NIR). Optical chemical sensors have several advantages over conventional electricity-based sensors, in terms of selectivity, immunity to electromagnetic interference, higher sensitivity, and they are also relatively inexpensi…

Thermoelastic stress analysis by means of an infrared scanner and a two-dimensional fast Fourier transform-based lock-in technique

An infrared thermographic experimental set-up has been proposed and evaluated towards the capability to measure thermoelastic-effect-induced temperature changes. A standard infrared thermocamera with a nominal noise-equivalent temperature difference (NETD) resolution of 0.12 K has been employed to measure the temperature from unidirectional glass-reinforced plastic tensile coupons under cyclic sinusoidal loads. The raster scanning mode of the camera single detector produces a time delay in acquiring the signal from two succeeding pixels on the same row, and from consecutive scanned rows. By exploiting the acquired dwell times, it was possible to produce a periodic pattern on the thermal ma…

Optical characterization of polystyrene direct opals and of inverse-opal hydrogels

Thermal Characterization of Friction Stir Welded Butt Joints

Functional consequences of prey acclimation to ocean acidification for the prey and its predator

Ocean acidification is the suite of chemical changes to the carbonate system of seawater as a consequence of anthropogenic carbon dioxide (CO2) emissions. Despite a growing body of evidences demonstrating the negative effects of ocean acidification on marine species, the consequences at the ecosystem level are still unclear. One factor limiting our ability to upscale from species to ecosystem is the poor mechanistic understanding of the functional consequences of the observed effects on organisms. This is particularly true in the context of species interactions. The aim of this work was to investigate the functional consequence of the exposure of a prey (the mussel Brachidontes pharaonis) t…

Rilevamento Sperimentale delle Storie di Temperatura in Processi di Friction Stir Welding di Lamiere di Titanio

A study on the effect of contact pressure during physical activity on photoplethysmographic heart rate measurements

Heart rate (HR) as an important physiological indicator could properly describe global subject&rsquo

A preliminary investigation of the effect of contact pressure on the accuracy of heart rate monitoring by wearable PPG wrist band

The increase of safety and health monitor of workers has become a crucial objective to prevent excessive physical workloads, injuries, accidents and errors. Heart rate (HR) is a very important physiological indicator which could properly describe the workers’ physical status. Recently, wearable photoplethysmographic (PPG) wristband trackers have been utilized to measure HR without hindering normal gesture of workers. However, the quality of PPG signals is highly affected by human physical motions, resulting in a poor reliable HR estimation. Specifically, during different activities and gestures, PPG sensor contact pressures may have an impact on the quality of the heart rate signal. To appr…

Air-coupled imaging method applied to the study and conservation of paintings

Thermoelastic stress analysis of a 2D stress field using a single detector infrared scanner and lock-in filtering

A low resolution, low cost, fast infrared scanner is used to acquire the temperature change along a line on the surface of cyclically loaded samples. The temperature signal is sampled versus time by exploiting the raster scanning movement of the thermocamera single detector. The temperature data is then post-processed by a Fast Fourier Transform based lock- in algorithm implemented in MATLAB ® , in order to filter out the thermoelastic effect induced temperature change. A procedure is also implemented in order to extend the data sampling time by opportunely synchronising successively grabbed data frames. The effectiveness of such synchronisation procedure is first demonstrated by performing…

Misfit evaluation of dental implant-supported metal frameworks manufactured with different techniques: Photoelastic and strain gauge measurements

This study aims to compare in-vitro the fitting accuracy of implant-supported metal frameworks used for full-arch orthodontic restoration. The hypotheses tested were as follows: (1) for a fixed implant morphology, strains developed within the framework depend on how the framework had been fabricated and (2) stresses transferred to the implant–bone interface are related to the amount of framework misfit. Metal frameworks were fabricated using four different manufacturing techniques: conventional lost-wax casting, resin cement luting, electrospark erosion, and computer-aided design/computer-aided manufacturing milling. Each framework was instrumented with three strain gauges to measure strai…

MONITORAGGIO DEL PROCESSO DI CURA DI COMPOSITI LAMINATI MEDIANTE SENSORI IN FIBRA OTTICA

Photonic crystal hydrogel films responsive to ethanol vapors

A Hybrid Frequency-Space Approach for Shape Measurement by Shadow Moirè Technique with Carrier Fringe Pattern

In this paper, a novel methodology to process fringe pattern is presented. The core of the signal processing technique is the use of the direction information, a modulo 2π quantity that locally informs about the direction along which fringes grow with maximum rate. By using this information, it was possible to perform adaptive, direction - and orientation-based operations on fringe images in order to remove unwanted effects, to enhance the contrast and to extract the phase information encoded. The method has been applied on shadow moiré interferograms with carrier fringes in order to measure the surface of small objects. The developed algorithm allows to process fringes whose phase informat…

Electronic speckle pattern interferometry for the analysis of wood bending behaviour

A Study on the Measurement Instrumentation for a Custom-Made Bipendulum Impact Testing Machine

Experimental investigations of structures under impact loads are normally carried out by means of drop-weight testing rigs, which are often tailor made, and require sensors for fast transient measurement of mechanical quantities (namely, force, displacement, velocity, and absorbed energy). Since these tests are quite expensive, time consuming, and, often, not repeatable, the sensors must provide reliable and interpretable results in the first trial. In this paper, a thorough study on the measurement instrumentation suitable to carry out reliable low-velocity impact tests by means of a custom-made bipendulum impact testing machine is presented. Attention has been focused on the choice of the…

On the Stiffness and the Reinforcement Effect of Electrical Resistance Strain Gauges

The reinforcement effect of a strain gauge installed on low modulus materials can be significant. The increasing use of low modulus materials requires therefore the evaluation of such effect. This paper concerns the relationship between the local reinforcement effect and the strain gauge stiffness. The conclusion is that the gauge stiffness alone does not allow the user a thorough evaluation of the reinforcement effect.