Use of wearable systems for the detection of chest-abdominal wall movement aimed at respiratory monitoring in sport: a scoping review on available data.

There is a significant request for wearable systems for vital signs and athletic performance monitoring during sport practice, both in professional and non-professional fields. Respiratory rate is a rather neglected parameter in this field, but several studies show that it is a strong marker of physical exertion. The aim of the present scoping review is to evaluate the number and kind of existing studies on wearable technologies for the analysis of the chest wall movement for respiratory monitoring in sport and fitness. The review included studies investigating the use of contact-based wearable techniques for the detection of chest wall movement for respiratory monitoring during professional or amateur sport, during fitness and physical activity. The search was conducted on PubMed/Medline, Scopus and Google Scholar electronic databases using keywords. Data extracted were entered into a Microsoft Excel spreadsheet by the leading author and then double-checked by the second author. A total of 25 descriptive studies met the inclusion criteria. Few studies on small number of athletes were found, technologies were often evaluated without a reference system, data on participants are sometimes missing. To date, we are not able to draw conclusions on which is the best and most reliable device to use during sport practice.

A Touchless system for image visualization during surgery: preliminary experience in clinical settings.

Today clinicians may access large medical datasets, but very few systems have been designed to allow a practical and efficient exploration of data directly in critical medical environments such as operating rooms (OR). This work aims to assess during tests in laboratory and clinical settings a Surgery Touchless System (STS). This system allows clinicians to interact with medical images by using two different approaches: a gesture recognition and a voice recognition based system. These two methods are based on the use of a Microsoft Kinect and of a selective microphone, respectively. The STS allows navigating in a specifically designed interface, to perform several tasks, among others, to manipulate biomedical images. In this article, we assessed both the recognitions approaches in laboratory with 5 users. In addition, the STS was tested using only the voice-based recognition approach in clinical settings. The assessment was performed during three procedures by two interventionalradiologists. The five volunteers and the 2 radiologists filled two questionnaires to assess the system. The system usability was positively evaluated in laboratory tests. From clinical trials emerged that the STS was considered safe and useful by both the radiologists: they used the system an averaged number of times of 10 and 15 for patients, and found the system useful. These promising results allow considering this system useful for providing information not otherwise accessible and limiting the impact of human error during the operation. Future work will be focused on the use of the STS on a high number and different types of procedure.

Polymer-coated fiber optic probe for the monitoring of breathing pattern and respiratory rate.

In recent years, no-invasive and small size systems are meeting the demand of the new healthcare system, in which the vital signs monitoring is gaining in importance. In this context, Fiber Bragg grating (FBG) sensors are becoming very popular and FBG-based systems could be used for monitoring vital signs. At the same time, FBG could be able to sense chemical parameters by the polymer functionalization. The aim of our study was investigating the ability of a polymer-coated FBG-based probe for monitoring breathing patterns and respiratory rates. We tested the proposed FBG-based probe on 9 healthy volunteers during spirometry, the most common pulmonary function test. Results showed the high accuracy of the proposed probe to detect respiratory rate. The comparison between the respiratory rates estimated by the probe with the ones by the spirometer showed the absolute value of the percentage errors lower than 2.07% (in the 78% of cases <.91%). Lastly, a Bland Altman analysis was performed to compare the instantaneous respiratory rate values gathered by the spirometer and the FBG probe showing the feasibility of breath-by-breath monitoring by the proposed probe. Results showed a bias of 0.06± 2.90 $\mathrm{breaths}\square {\mathrm {min}}^{-1}$. Additionally, our system was able to follow the breathing activities and monitoring the breathing patterns.

Wearable textile based on silver plated knitted sensor for respiratory rate monitoring.

Wearable systems are gaining broad acceptance for monitoring physiological parameters in several medical applications. Among a number of approaches, smart textiles have attracted interest because they are comfortable and do not impair patients' movements. In this article, we aim at developing a smart textile for respiratory monitoring based on a piezoresistive sensing element. Firstly, the calibration curve of the system and its hysteresis have been investigated. Then, the proposed system has been assessed on 6 healthy subjects. The volunteers were invited to wear the system to monitor their breathing rate. The results of the calibration show a good mean sensitivity (i.e., approximately 0.11V·%-1); although the hysteresis is not negligible, the system can follow the cycles also at high rates (up to 36 cycle·min-1). The feasibility assessment on 6 volunteers (two trials for each one) shows that the proposed system can estimate with good accuracy the breathing rate. Indeed, the results obtained by the proposed system were compared with the ones collected with a spirometer, used as reference. Considering all the experiments, a mean percentage error was approximately 2%. In conclusion, the proposed system has several valuable features (e.g., the sensing element is lightweight, the sensitivity is high, and it is possible to develop comfortable smart textile); in addition, the promising performances considering both metrological properties and assessment on volunteers foster future tests focused on: i) the possibility of developing and system embedding several sensing elements, and ii) to develop a wireless acquisition system, to allow comfortable and long-term acquisition in both patients and during sport activities.

Ex vivo animal-model assessment of a non-invasive system for loss of resistance detection during epidural blockade.

During recent decades epidural analgesia has gained widespread recognition in many applications. In this complex procedure, anaesthetist uses a specific needle to inject anesthetic into the epidural space. It is crucial the appropriate insertion of the needle through inhomogeneous tissues placed between the skin and the epidural space to minimize anesthetic-related complications (e.g., nausea, headache, and dural puncture). Usually, anaesthetists perform the procedure without any supporting tools, and stop pushing the syringe when they sense a loss of resistance (LOR). This phenomenon is caused by the physical properties of the epidural space: the needle breaks the ligamentum flavum and reaches the epidural space, in this stage the anaesthetist perceives a LOR because the epidural space is much softer than the ligamentum flavum. To support the clinician in this maneuver we designed a non-invasive system able to detect the LOR by measuring the pressure exerted on the syringe plunger to push the needle up to the epidural space. In a previous work we described the system and its assessment during in vitro tests. This work aims at assessing the feasibility of the system for LOR detection on a more realistic model (ex vivo pig model). The system was assessed by analyzing: its ability to hold a constant value (saturation condition) during the insertion of the needle, and its ability to detect the entrance within the epidural space by a decrease of the system's output. Lastly, the anaesthetist was asked to assess how the ex vivo procedure mimics a clinical scenario. The system reached the saturation condition during the needle insertion; this feature is critical to avoid false positive during the procedure. However, it was not easy to detect the entrance within the epidural space due to its small volume in the animal model. Lastly, the practitioner found real the model, and performed the procedures in a conventional manner because the system did not influence his actions.

Temperature influence on the response at low airflow of a variable orifice flowmeter.

In mechanical ventilation, in particular when neonates are ventilated, it is crucial to accurately control the amount of the gas delivered to the patients. Mechanical ventilators are equipped with one of more flowmeters. The signal of the flowmeter is used as feedback to control the amount of gas delivered to the patients. Therefore, the accuracy of the flowmeter plays a crucial role in the accurate adjustment of the gas amount delivered by the ventilator. Among several solutions, variable area orifice meters (VAOMs) have several valuable features (e.g., good accuracy, and adequate frequency response), moreover they have the main advantage, with respect to orifice meters, related to the linearity of the response. Despite of their spread in this field, there are not studies focused on the analysis of the air temperature influence on VAOMs response. This study focuses on this topic by investigating the gas temperature influence on the response of a commercial VAOM. Experiments have been performed at low airflow (up to 1.5 L·min-1) and at four different temperatures (i.e., from 22°C to 38°C) covering the range of interest in the field of artificial ventilation. Results show that the response of the VAOM under test is sensitive to temperature: at constant airflow the higher the temperature the higher the sensor output. This analysis may be useful to add correction to sensor output in order to reject the influence of temperature, so to minimize the measurement error due to this factor.

A wearable textile for respiratory monitoring: Feasibility assessment and analysis of sensors position on system response.

The interest on wearable textiles to monitor vital signs is growing in the research field and clinical scenario related to the increasing demands of long-term monitoring. Despite several smart textile-based solutions have been proposed for assessing the respiratory status, only a limited number of devices allow the respiratory monitoring in a harsh environment or in different positions of the human body. In this paper, we investigated the performances of a smart textile for respiratory rate monitoring characterized by 12 fiber optic sensors (i.e., fiber Bragg grating) placed on specific landmarks for compartmental analysis of the chest wall movements during quiet breathing. We focused on the analysis of the influence of sensor position on both peak-to-peak amplitude of sensors output and accuracy of respiratory rate measurements. This analysis was performed on two participants, who wore the textile in two positions (i.e., standing and supine). Bland-Altman analysis on respiratory rate showed promising results (better than 0.3 breaths per minute). Referring to the peak-to-peak output amplitude, the abdomen compartment showed the highest excursions in both the enrolled participants and positions. Our findings open up new approaches to design and develop smart textile for respiratory rate monitoring.

Tapered fiber optic applicator for laser ablation: Theoretical and experimental assessment of thermal effects on ex vivo model.

Laser Ablation (LA) is a minimally invasive technique for tumor removal. The laser light is guided into the target tissue by a fiber optic applicator; thus the physical features of the applicator tip strongly influence size and shape of the tissue lesion. This study aims to verify the geometry of the lesion achieved by a tapered-tip applicator, and to investigate the percentage of thermally damaged cells induced by the tapered-tip fiber optic applicator. A theoretical model was implemented to simulate: i) the distribution of laser light fluence rate in the tissue through Monte Carlo method, ii) the induced temperature distribution, by means of the Bio Heat Equation, iii) the tissue injury, by Arrhenius integral. The results obtained by the implementation of the theoretical model were experimentally assessed. Ex vivo porcine liver underwent LA with tapered-tip applicator, at different laser settings (laser power of 1 W and 1.7 W, deposited energy equal to 330 J and 500 J, respectively). Almost spherical volume lesions were produced. The thermal damage was assessed by measuring the diameter of the circular-shaped lesion. The comparison between experimental results and theoretical prediction shows that the thermal damage discriminated by visual inspection always corresponds to a percentage of damaged cells of 96%. A tapered-tip applicator allows obtaining localized and reproducible damage close to spherical shape, whose diameter is related to the laser settings, and the simple theoretical model described is suitable to predict the effects, in terms of thermal damage, on ex vivo liver. Further trials should be addressed to adapt the model also on in vivo tissue, aiming to develop a tool useful to support the physician in clinical application of LA.

A cost-effective, non-invasive system for pressure monitoring during epidural needle insertion: Design, development and bench tests.

Epidural blockade procedures have gained large acceptance during last decades. However, the insertion of the needle during epidural blockade procedures is challenging, and there is an increasing alarming risk in accidental dural puncture. One of the most popular approaches to minimize the mentioned risk is to detect the epidural space on the base of the loss of resistance (LOR) during the epidural needle insertion. The aim of this paper is to illustrate an innovative and non-invasive system able to monitor the pressure exerted during the epidural blockade procedure in order to detect the LOR. The system is based on a Force Sensing Resistor (FSR) sensor arranged on the top of the syringe's plunger. Such a sensor is able to register the resistance opposed to the needle by the different tissues transducing the pressure exerted on the plunger into a change of an electrical resistance. Hence, on the base of a peculiar algorithm, the system automatically detects LOR providing visual and acoustic feedbacks to the operator improving the safety of the procedure. Experiments have been performed to characterize the measurement device and to validate the whole system. Notice that the proposed solution is able to perform an effective detection of the LOR.

Temperature monitoring during radiofrequency ablation of liver: in vivo trials.

Radiofrequency ablation (RFA) is a minimally invasive procedure used to treat tumors by means of hyperthermia, mostly through percutaneous approach. The tissue temperature plays a pivotal role in the achievement of the target volume heating, while sparing the surrounding healthy tissue from thermal damage. Several techniques for thermometry during RFA are investigated, most of them based on the use of single-point measurement system (e.g., thermocouples). The measurement of temperature map is crucial for the real-time control and fine adjustment of the treatment settings, to optimize the shape and size of the ablated volume. The recent interest about fiber optic sensors and, among them, fiber Bragg gratings (FBGs) for the monitoring of thermal effects motivated further investigation. In particular, the feature of FBGs to form an array of several elements, thus to be inscribed within the same fiber, allows the use of a single probe for the multi-points monitoring of the tissue temperature during RFA. Hence, the aim of this study is the development and characterization of a needle-like probe embedding an array of three FBGs, which was tested on pig liver during in vivo trials. The needle allows a safe and easy insertion of the fiber optic within the liver. It was inserted by ultrasound guidance into the liver, and monitored the change of tissue temperature during RFA controlled by the roll-off technique. Also the measurement error induced by breathing movements of the liver was assessed (less than 3 °C). Results encourage the use of the probe in clinical settings, as well as the improvement of some features, e.g., a higher number of FBGs for performing quasi-distributed measurement.

Optical measurement of breathing: algorithm volume calibration and preliminary validation on healthy trained subjects.

The use of optical technologies may be beneficial when measuring breathing biomechanics. The purpose of this study was twofold: i) to enhance the optoelectronic plethysmography (OEP) algorithm performance for the volume estimation by the use of a novel volume calibration procedure and ii) to compare the OEP volumes gained by a commercial optoelectronic system against actual respiratory volumes measured by a breath-by-breath gas analyzer (BbB). The OEP volume algorithm calibration was performed by the use of a novel volume calibration procedure based on both a calibrator device that delivered known volumes changes and one ad-hoc designed software for the static and dynamic calibration analysis. OEP algorithm threshold, accuracy, repeatability and the volume algorithm calibration were investigated. Tidal volume (VT) measurements performed simultaneously by the calibrated OEP algorithm and BbB analyzer were compared. VT measured simultaneously by OEP and BbB was collected during submaximal exercise tests in five trained healthy participants in two conditions (with hunched shoulders and in normal shoulder position). The two methods were compared by linear regression and Bland-Altman analysis in both positions. The average difference between methods and the discrepancy were calculated. The OEP-BbB correlation was high in both positions, R2=0.92 and R2=0.97 for hunch and normal one, respectively. Bland-Altman analysis demonstrated that OEP algorithm systematic difference was lower than 100mL. The limits of agreement assessed in both positions are comparable. The difference between measurements suggesting that OEP may be a useful tool to analyze chest wall volume changes and breathing mechanics during intense exercise.

A novel tool and procedure for in-situ volumetric calibration of motion capture systems for breathing analysis.

Optical motion capture systems are widely used in biomechanics although have not been significantly explored for measuring volumes and volume variations yet. The aim of this study was to propose and test a completely novel procedure for the calibration of motion capture systems for the breathing analysis in terms of volume measurements, by the use of a tool consisting in an ad-hoc designed in-situ calibration device (CD) and two algorithms for calibration. Both the calibration tool and the calibration procedure performed in the range 0-2780mL on an Optoelectronic Plethysmography (OEP) system are presented. The CD delivered known volume (ΔVCD) variations to the OEP; the two algorithms performed the calibration by the comparison between ΔVCD and OEP recorded volume (ΔVOEP), in both static and dynamic conditions. Discrimination threshold, accuracy, precision and repeatability for the volume variation measurements have been evaluated, as well as the calibration curve of the OEP. OEP volume threshold of ±8.92mL was assessed; the volume measurement accuracy was always better than 6.0% of measured volume, and a volume repeatability of ±2.7mL was found. Lastly, the calibration curve was assessed to be ΔVOEP= 0.962·ΔVCD. Results demonstrate that the proposed calibration procedure can be useful to provide an in-situ accurate calibration of motion capture systems in the volume analysis, to optimize the hardware and the software of the available system for volume measurement as well as to establish the motion capture system appropriateness, in terms of technical suitability and data quality.

Design and preliminary assessment of a smart textile for respiratory monitoring based on an array of Fiber Bragg Gratings.

Comfortable and easy to wear smart textiles have gained popularity for continuous respiratory monitoring. Among different emerging technologies, smart textiles based on fiber optic sensors (FOSs) have several advantages, like Magnetic Resonance (MR)-compatibility and good metrological properties. In this paper we report on the development and assessment of an MR-compatible smart textiles based on FOSs for respiratory monitoring. The system consists of six fiber Bragg grating (FBG) sensors glued on the textile to monitor six compartments of the chest wall (i.e., right and left upper thorax, right and left abdominal rib cage, and right and left abdomen). This solution allows monitoring both global respiratory parameters and each compartment volume change. The system converts thoracic movements into strain measured by the FBGs. The positioning of the FBGs was optimized by experiments performed using an optoelectronic system. The feasibility of the smart textile was assessed on 6 healthy volunteers. Experimental data were compared to the ones estimated by an optoelectronic plethysmography used as reference. Promising results were obtained on both breathing period (maximum percentage error is 1.14%), inspiratory and expiratory period, as well as on total volume change (mean percentage difference between the two systems was ~14%). The Bland-Altman analysis shows a satisfactory accuracy for the parameters under investigation. The proposed system is safe and non-invasive, MR-compatible, and allows monitoring compartmental volumes.

Temperature monitoring during microwave ablation in ex vivo porcine livers.

OBJECTIVE: The aim of the present study was to assess the temperature map and its reproducibility while applying two different MWA systems (915 MHz vs 2.45 GHz) in ex vivo porcine livers. MATERIALS AND METHODS: Fifteen fresh pig livers were treated using the two antennae at three different settings: treatment time of 10 min and power of 45 W for both systems; 4 min and 100 W for the 2.45 GHz system. Trends of temperature were recorded during all procedures by means of fiber optic-based probes located at five fixed distances from the antenna, ranging between 10 mm and 30 mm. Each trial was repeated twice to assess the reproducibility of temperature distribution. RESULTS: Temperature as function of distance from the antenna can be modeled by a decreasing exponential trend. At the same settings, temperature obtained with the 2.45 GHz system was higher than that obtained with the 915 MHz thus resulting into a wider area of ablation (diameter 17 mm vs 15 mm). Both systems showed good reproducibility in terms of temperature distribution (root mean squared difference for both systems ranged between 2.8 °C and 3.4 °C). CONCLUSIONS: When both MWA systems are applied, a decreasing exponential model can predict the temperature map. The 2.45 GHz antenna causes higher temperatures as compared to the 915 MHz thus, resulting into larger areas of ablation. Both systems showed good reproducibility although better results were achieved with the 2.45 GHz antenna.

Design and characterization of a measurement system for monitoring pressure exerted by bronchial blockers: In vitro trials.

Bronchial blockers (BBs) allow occluding the bronchial duct and collapsing the "dependent" lung in a number of thoracic surgery. The occlusion is obtained through a cuff that, inflated with a proper air volume, exerts a pressure, Pe, on the inner wall of the mainstem bronchus. In this work a measurement chain, based on two piezorestistive force sensors, was developed and calibrated to measure Pe exerted by six BBs, as a function of inflated volume on in vitro models (two latex ducts with diameters similar to the ones of the adult mainstem bronchi: 12 mm and 15 mm). Pe showed wide changes considering different BBs, and significantly increases with the decrease of the model's diameter, at the same inflated volume. Lastly, the minimum occlusive volume (MOV) to sail the two models was estimated for each BB. These experiments were performed by applying a pressure difference across the cuff of 25 cmH2O, in order to simulate the worst condition in a clinical scenario. Results show that MOV depends on both the type of BB and the duct diameter. The knowledge of this volume allows estimating the minimum value of Pe exerted by BBs to avoid air leakage.

Feasibility assessment of CT-based thermometry for temperature monitoring during thermal procedure: Influence of ROI size and scan setting on metrological properties.

Computed tomography (CT) thermometry belongs to the wide class of non-invasive temperature monitoring techniques, which includes ultrasound and Magnetic Resonance thermometry. Non-invasive techniques are particularly attractive to be used in hyperthermal procedures for their ability to produce a three-dimensional temperature map and because they overcome the risks related to the insertion of sensing elements.

Goniometric measurement for the estimation of anisotropy coefficient of human and animal pancreas.

Estimation of optical properties of biologic tissues is determinant for laser dosimetry in medical applications. Tissues highly absorb and scatter the light in near infrared spectrum, where the laser provides therapeutic effects. Novel frontiers of clinical practice, e.g., the employment of laser light for the treatment of pancreatic cancer, require information about pancreas-laser interaction, which are crucial for therapy management. The property of biological tissues to scatter the light traveling through is described by the anisotropy coefficient (g). The relationship between g and the angular distribution of the scattered light is described by Henyey-Greenstein phase function. The measurement of angular distribution of scattered light is performed by the goniometric technique. This paper describes the estimation of g of ex vivo pancreas at 1064 nm, performed by a goniometric-based system, where a photodetector measures intensities of scattered light at fixed angles between -120° and 120°. A two-term Henyey-Greenstein phase function has been employed to estimate anisotropy coefficient for forward (gfs) and backward scattering (gbs). Experimental trails were performed to assess the repeatability of measurement system: percentage value of standard deviation is generally lower than 8% for angles higher (lower) than 13° (13°). Measurements were performed for the first time on healthy swine pancreas, aiming to investigate the influence of coagulation temperature: gfs decreases from 0.94 (at 25 °C) to 0.93 (at 80 °C). Afterwards, the same set up has been employed for the estimation of g of human pancreas affected by neuroendocrine tumor, which presented an estimated values for gfs of 0.89.

Magnetic Resonance-compatible needle-like probe based on Bragg grating technology for measuring temperature during Laser Ablation.

Temperature monitoring in tissue undergone Laser Ablation (LA) may be particularly beneficial to optimize treatment outcome. Among many techniques, fiber Bragg grating (FBG) sensors show valuable characteristics for temperature monitoring in this medical scenario: good sensitivity and accuracy, and immunity from electromagnetic interferences. Their main drawback is the sensitivity to strain, which can entail measurement error for respiratory and patient movements. The aims of this work are the design, the manufacturing and the characterization of a needle-like probe which houses 4 FBGs. Three FBGs have sensitive length of 1 mm and are used as temperature sensors; one FBG with length of 10 mm is used as reference and to sense eventual strain. The optical fiber housing the FBGs was encapsulated within a needle routinely used in clinical practice to perform MRI-guided biopsy. Two materials were used for the encapsulation: i) thermal paste for the 3 FBGs used for temperature monitoring, to maximize the thermal exchange with the needle; ii) epoxy resin for the reference FBG, to improve its sensitivity to strain. The static calibration of the needle-like probe was performed to estimate the thermal sensitivity of each FBG; the step response was investigated to estimate the response time. FBGs 1 mm long have thermal sensitivity of 0.01 nm·°C(-1), whereas the reference FBG presents 0.02 nm·°C(-1). For all FBGs, the response time was in the order of 100 ms. Lastly, experiments were performed on ex vivo swine liver undergoing LA to i) evaluate the possible presence of measurement artifact, due to the direct absorption of laser light by the needle and ii) assess the feasibility of the probe in a quasi clinical scenario.

Evaluation of optoelectronic Plethysmography accuracy and precision in recording displacements during quiet breathing simulation.

Opto-electronic Plethysmography (OEP) is a motion analysis system used to measure chest wall kinematics and to indirectly evaluate respiratory volumes during breathing. Its working principle is based on the computation of marker displacements placed on the chest wall. This work aims at evaluating the accuracy and precision of OEP in measuring displacement in the range of human chest wall displacement during quiet breathing. OEP performances were investigated by the use of a fully programmable chest wall simulator (CWS). CWS was programmed to move 10 times its eight shafts in the range of physiological displacement (i.e., between 1 mm and 8 mm) at three different frequencies (i.e., 0.17 Hz, 0.25 Hz, 0.33 Hz). Experiments were performed with the aim to: (i) evaluate OEP accuracy and precision error in recording displacement in the overall calibrated volume and in three sub-volumes, (ii) evaluate the OEP volume measurement accuracy due to the measurement accuracy of linear displacements. OEP showed an accuracy better than 0.08 mm in all trials, considering the whole 2m(3) calibrated volume. The mean measurement discrepancy was 0.017 mm. The precision error, expressed as the ratio between measurement uncertainty and the recorded displacement by OEP, was always lower than 0.55%. Volume overestimation due to OEP linear measurement accuracy was always <; 12 mL (<; 3.2% of total volume), considering all settings.

Design, development and experimental validation of a non-invasive device for recording respiratory events during bottle feeding.

In newborns, a poor coordination between sucking, swallowing and breathing may undermine the effectiveness of oral feeding and signal immaturity of Central Nervous System. The aim of this work is to develop and validate a non-invasive device for recording respiratory events of newborns during bottle feeding. The proposed device working principle is based on the convective heat exchanged between two hot bodies and the infants' breathing. The sensing elements are inserted into a duct and the gas exchanged by infants is conveyed into this duct thanks to an ad hoc designed system to be mounted on a commercial feeding bottle. Two sets of experiments have been carried out in order to investigate the discrimination threshold of the device and characterize the sensor response at oscillating flows. The effect of distance and tilt between nostrils and device, and the breathing frequency, have been investigated simulating nostrils and neonatal respiratory pattern. The device has a discrimination threshold lower than 0.5 L/min at both 10° and 20° of tilt. Distance for these two settings does not affect the threshold in the investigated range (10-20 mm). Moreover, the device is able to detect breathing events, and to discriminate the onset of expiratory phase, during a neonatal respiratory task delivered by a lung simulator. The results foster the successful application of this device to the assessment of the temporal breathing pattern of newborns during bottle feeding with a non-invasive approach.