We present a simple, low-cost method for measuring multiple physiological parameters using a basic webcam. By applying independent component analysis on the color channels in video recordings, we extracted the blood volume pulse from the facial regions. Heart rate (HR), respiratory rate, and HR variability (HRV, an index for cardiac autonomic activity) were subsequently quantified and compared to corresponding measurements using Food and Drug Administration-approved sensors. High degrees of agreement were achieved between the measurements across all physiological parameters. This technology has significant potential for advancing personal health care and telemedicine.

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Advancements in Noncontact, Multiparameter Physiological Measurements Using a Webcam

Renewable energy sources have gained much attention due to the recent energy crisis and the urge to get clean energy. Among the main options being studied, wind energy is a strong contender because of its reliability due to the maturity of the technology, good infrastructure and relative cost competitiveness. In order to harvest wind energy more efficiently, the size of wind turbines has become physically larger, making maintenance and repair works difficult. In order to improve safety considerations, to minimize down time, to lower the frequency of sudden breakdowns and associated huge maintenance and logistic costs and to provide reliable power generation, the wind turbines must be monitored from time to time to ensure that they are in good condition. Among all the monitoring systems, the structural health monitoring (SHM) system is of primary importance because it is the structure that provides the integrity of the system. SHM systems and the related non-destructive test and evaluation methods are discussed in this review. As many of the methods function on local damage, the types of damage that occur commonly in relation to wind turbines, as well as the damage hot spots, are also included in this review.

https://iopscience.iop.org/article/10.1088/0957-0233/19/12/122001/pdf

Structural health monitoring for a wind turbine system: a review of damage detection methods

Complex phenomena in photonics, in particular, dynamical properties of semiconductor lasers due to delayed coupling, are reviewed. Although considered a nuisance for a long time, these phenomena now open interesting perspectives. Semiconductor laser systems represent excellent test beds for the study of nonlinear delay-coupled systems, which are of fundamental relevance in various areas. At the same time delay-coupled lasers provide opportunities for photonic applications. In this review an introduction into the properties of single and two delay-coupled lasers is followed by an extension to network motifs and small networks. A particular emphasis is put on emerging complex behavior, deterministic chaos, synchronization phenomena, and application of these properties that range from encrypted communication and fast random bit sequence generators to bioinspired information processing.

/pdf/complex-photonics-dynamics-and-applications-of-delay-coupled-1llx3j8d4d.pdf

Complex photonics: Dynamics and applications of delay-coupled semiconductors lasers

In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques.

/pdf/fibre-optic-sensors-for-structural-health-monitoring-of-izgdedczqo.pdf

Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications.

Laser Doppler Vibrometry: Development of advanced solutions answering to technology's needs

A review of recent experimental and theoretical results concerning laser diode self-mixing velocimetry is presented, showing that this technique can be deployed to measure velocity and vibration of solid targets with an extremely simple optical setup. This technique reduces optical alignment problems and achieves results comparable to those obtained by the conventional laser Doppler velocimetry (LDV) approach. It is demonstrated that the self-mixing signal can be processed to recover the target velocity and vibration by applying the same analysis method used for LDV. An optimal signal processing method is then proposed to recover the target velocity with good accuracy, also in the presence of relevant speckle disturbance. Application to the measurement of sub-micron vibrations is also demonstrated, using a self-mixing vibrometer instrument capable of 5-nm accuracy. As an example, the characterization of response and hysteresis of piezoceramic transducers (PZTs) is carried out. These results illustrate the effectiveness of the self-mixing technique in the field of laser velocimetry, opening the way to new applications where compactness and low cost of the measuring apparatus are essential.

/pdf/self-mixing-laser-diode-velocimetry-application-to-vibration-2j8xcskzjz.pdf

Self-mixing laser diode velocimetry: application to vibration and velocity measurement

We present an optical non-contact method for heart beat monitoring, based on the measurement of chest wall movements induced by the pumping action of the heart, which is eligible as a surrogate of electrocardiogram (ECG) in assessing both cardiac rate and heart rate variability (HRV). The method is based on the optical recording of the movements of the chest wall by means of laser Doppler interferometry. To this aim, the ECG signal and the velocity of vibration of the chest wall, named optical vibrocardiography (VCG), were simultaneously recorded on 10 subjects. The time series built from the sequences of consecutive R waves (on ECG) and vibrocardiographic (VV) intervals were compared in terms of heart rate (HR). To evaluate the ability of VCG signals as quantitative marker of the autonomic activity, HRV descriptors were also calculated on both ECG and VCG time series. HR and HRV indices obtained from the proposed method agreed with the rate derived from ECG recordings (mean percent difference <3.1%). Our comparison concludes that optical VCG provides a reliable assessment of HR and HRV analysis, with no statistical differences in term of gender are present. Optical VCG appears promising as non-contact method to monitor the cardiac activity under specific conditions, e.g., in magnetic resonance environment, or to reduce exposure risks to workers subjected to hazardous conditions. The technique may be used also to monitor subjects, e.g., severely burned, for which contact with the skin needs to be minimized.

Optical vibrocardiography: a novel tool for the optical monitoring of cardiac activity.

Non-contact cardiac monitoring from carotid artery using optical vibrocardiography

At present there is a clear need for non-contact monitoring of the physiological signs of the patients. The system proposed in this paper aims to measure the heart rate of neonatal infants without any direct contact with the patient. The solution proposed is based on the use of standard, low-cost and commercially available digital webcamera by which it has been possible to observe defined portions of the patient face; the sequence of such images has then been used, by a specifically developed algorithm (based on Indipendent Component Analysis), to extract the heart rate of the patients. Data collected on 7 patients demonstrate the feasibility of the measurement method proposed. Data acquired on the same patients with standard electrocardiography (ECG) has been used for comparison. Bland-Altman analysis of data show close correlation of the heart rates measured with the two approaches (correlation coefficient of 0.94) with an uncertainty of 4.5 bpm (k=1). This technique has a valuable interest for the use in clinical environment as non-contact, easily deployable and economic monitoring system, but it also shows an interesting potential for remote, home health monitoring.

Heart rate measurement in neonatal patients using a webcamera

Many conventional medical monitoring devices, while not technically invasive, are nevertheless obtrusive insofar as they require contact with the patient. This obtrusiveness sometimes poses problems in daily clinical practice. The need for contact with electrodes or transducers is particularly relevant in the case of patients recovering in intensive care units where continuous monitoring is required, in turn requiring continuous direct transducer contact for prolonged periods. Among the many physiological parameters commonly acquired, the respiratory and the cardiac rates of the patients are of primary importance. Typically these two parameters are measured respectively using spirometry and electrocardiography (ECG), both involving obtrusive measurement systems requiring contact with the patient with an air conduit and electrodes. This paper presents an optical measurement method for the simultaneous assessment of respiration and heart rates based on the measurement of the chest wall movements, associated with inspiratory/expiratory activities of the lungs and by the mechanical pumping action of the heart. The measurement method has been adapted for use with preterm infants and it has been applied to 55 patients recovering in a Neonatal Intensive Care Unit. The method is based on the use of a laser Doppler vibrometer (LDVi) pointed at the left, ventral thoracic surface of the patient. LDVi-based measures of respiration and heart rate have been simultaneously acquired for each patient, in parallel with the same quantities acquired using conventional reference instrumentation (flow-meter and ECG) for comparison purposes. Results show that for respiration rate, differences with respect to the spirometer data are <3%, while for the cardiac rate they are <6% with respect to ECG data. The method proposed in this paper has the advantage of requiring no contact with the patient. Moreover, it supports, by means of a single instrument, the simultaneous measurement of respiration and heart rates, thus reducing the burden of the number of electrodes, transducers, and other instrumentation that must be applied to the patient—a consideration that is particularly important in the Neonatal Intensive Care Unit. In addition to the measurement of respiration rate, we also describe the sensitivity of the LDVi method in detecting key respiration events (irregular inspiration/expiration cycles, apneas, and hiccups) which are relevant to clinical monitoring.

Lorenzo Scalise

Papers

Self-mixing laser diode velocimetry: application to vibration and velocity measurement

Optical vibrocardiography: a novel tool for the optical monitoring of cardiac activity.

Non-contact cardiac monitoring from carotid artery using optical vibrocardiography

Heart rate measurement in neonatal patients using a webcamera

An optical measurement method for the simultaneous assessment of respiration and heart rates in preterm infants