Sensors For Health Monitoring Research Articles

Wearable Electrospun Nanofibrous Sensors for Health Monitoring

Various electrospinning techniques can be used to produce nanofiber mats with randomly oriented or aligned nanofibers made of different materials and material mixtures. Such nanofibers have a high specific surface area, making them sensitive as sensors for health monitoring. The entire nanofiber mats are very thin and lightweight and, therefore, can be easily integrated into wearables such as textile fabrics or even patches. Nanofibrous sensors can be used not only to analyze sweat but also to detect physical parameters such as ECG or heartbeat, movements, or environmental parameters such as temperature, humidity, etc., making them an interesting alternative to other wearables for continuous health monitoring. This paper provides an overview of various nanofibrous sensors made of different materials that are used in health monitoring. Both the advantages of electrospun nanofiber mats and their potential problems, such as inhomogeneities between different nanofiber mats or even within one electrospun specimen, are discussed.

Magnetron sputtering preparation of flexible ZnO/AlN thin-films sensors with hybrid piezoelectric effect for broad-range human motions detection

Wearable sensors with excellent comfort, flexibility and fast response are widely applied in human-machine interactions, artificial skin, motion detection and healthcare monitoring. However, preparation processes of the most of current piezoelectric sensors are relatively expensive and complicate, limiting their mass productions in the applications. This work demonstrates the superior piezoelectric performance and stability of ZnO/AlN flexible thin films prepared by magnetron sputtering for broad-range human motions detection, and first-principles calculation are applied to reveal the complicate piezoelectric effect of the hybrid system. The ZnO/AlN hybrid thin films sensor exhibits superior piezoelectric performance and excellent reliability, with presenting high outputs voltage (3.63 V), high degree of response speed (42.33 ms), water stability and robust performance upon 10000 cycles. First-principles calculations reveal that formation of the ZnO/AlN interface facilitates charge transport and improves efficiency of carrier transport, and results in reduced in band gap and enhanced electrical conductivity. By applying the sensors in human health monitoring, the underlying behaviors can be determined by output voltage of the sensor in real-time. This work offers a sensitive, simple structured and robust solution for human motion detection.

Advances in Wearable Smart Chemical Sensors for Health Monitoring

The advancement of wearable technology has entered a new phase, leading to the creation of various wearable sensors due to the rise of technologies like IoT and AI. Wearable chemical sensors are essential components of wearable electronics and hold significant promise in monitoring health. This review reports on the recent achievements and advantages of portable smart chemical sensing for health monitoring and discusses portable chemical sensing using frictional/piezoelectric electrochemical generators, photovoltaics and thermal power accumulators. This paper also evaluates the potential of wearable chemical sensors for health monitoring.

Application of FBG sensor in health monitoring of engineering building structure: a review

Purpose The aging and deterioration of engineering building structures present significant risks to both life and property. Fiber Bragg grating (FBG) sensors, acclaimed for their outstanding reusability, compact form factor, lightweight construction, heightened sensitivity, immunity to electromagnetic interference and exceptional precision, are increasingly being adopted for structural health monitoring in engineering buildings. This research paper aims to evaluate the current challenges faced by FBG sensors in the engineering building industry. It also anticipates future advancements and trends in their development within this field. Design/methodology/approach This study centers on five pivotal sectors within the field of structural engineering: bridges, tunnels, pipelines, highways and housing construction. The research delves into the challenges encountered and synthesizes the prospective advancements in each of these areas. Findings The exceptional performance of FBG sensors provides an ideal solution for comprehensive monitoring of potential structural damages, deformations and settlements in engineering buildings. However, FBG sensors are challenged by issues such as limited monitoring accuracy, underdeveloped packaging techniques, intricate and time-intensive embedding processes, low survival rates and an indeterminate lifespan. Originality/value This introduces an entirely novel perspective. Addressing the current limitations of FBG sensors, this paper envisions their future evolution. FBG sensors are anticipated to advance into sophisticated multi-layer fiber optic sensing networks, each layer encompassing numerous channels. Data integration technologies will consolidate the acquired information, while big data analytics will identify intricate correlations within the datasets. Concurrently, the combination of finite element modeling and neural networks will enable a comprehensive simulation of the adaptability and longevity of FBG sensors in their operational environments.

A wide-frequency triboelectric vibration sensor for self-powered machinery health monitoring

Abnormal vibration is usually a precursor to structural damage and performance degradation industrial equipment and transportation. Vibration detection at critical locations such as electrical motors and bearings within large equipment has emerged as an indispensable method for machinery health monitoring. Current vibration detection instruments mostly need to be powered by cables or batteries, which has application limitations in complex moving equipment and restricted space. In this paper, a disc-like triboelectric nanogenerator (DL-TENG) with a multi-sized honeycomb structure is proposed as an innovative solution for achieving wide band and high precision acceleration detection of the vibration. Multi-diameter polytetrafluoroethylene (PTFE) balls are used as friction materials to achieve the high voltage output of the TENG, providing sufficient energy for the detection circuit. By carefully designing suitable honeycomb structures for PTFE balls of different diameters, the ability to detect broadband vibration signals is obtained. The experimental results demonstrate that DL-TENG with honeycomb structure and multi-size PTFE balls can detect acceleration signals ranging from 10 to 2000 Hz, and the acceleration measurement range can reach 1–11 m/s2 with an acceleration resolution of 0.1 m/s2. Moreover, DL-TENG can output more than 80 V peak-to-peak under vibration conditions of 11 m/s2. And under vibration conditions of 8 m/s2, the DL-TENG can fully charge a 100 μF capacitor to 5 V in just 100 seconds. By equipping a special circuit for DL-TENG, wireless self-powered vibration detection is realized. This study is expected to be applied in the scenario of vibration information collection in complex ring vibration environment and provides a new paradigm for the realization of self-powered vibration sensors.

Effect of ICCP on conductivity properties of carbon fiber bundles and CFRCM

The effectiveness of carbon fabric reinforced cementitious matrix (CFRCM) in impressed current cathodic protection (ICCP) and structural strengthening (SS) of reinforced concrete (RC) structures has been verified. Meanwhile, due to the piezoresistive effect of carbon fibers, CFRCM has been developed as a self-monitoring sensor for structural health monitoring (SHM). However, the conductivity properties of CFRCM and carbon fiber under ICCP will be subject to performance degradation due to anodic reaction, which may have adverse effects on their role in SHM, and the degradation in seawater sea-sand (chlorine-containing environments) is still unknown. In this study, simulated ICCP tests were carried out on carbon fiber bundles in different solution environments and mortar environments to investigate the influences and mechanisms of different ICCP current densities, electrification durations, electrification environments, fiber lengths, and mortar types on conductivity properties of carbon fiber bundles and CFRCM. The prediction models for resistance were established based on a large number of experimental measurements. The results show that changes in resistance of carbon fiber bundles and CFRCM under ICCP exhibit two-stage characteristics of linear growth and rapid growth. The presence of chloride ions in seawater sea-sand environments can share polarization currents, reduce electrode potential, and slow down carbon fiber degradation. The degradation rates of carbon fiber bundles under four electrification environments, from fast to slow, are as follows: normal mortar, seawater sea-sand mortar, saturated Ca(OH)2 solution, and saturated Ca(OH)2 solution prepared with seawater. This study aims to promote the development of CFRCM materials with the multifunctional properties of ICCP-SS and SHM, and to achieve rational utilization of seawater and sea-sand.

Retraction Note: Quantum photonics based music signal analysis with optical sensor in health monitoring using machine learning model

Retraction Note: Quantum photonics based music signal analysis with optical sensor in health monitoring using machine learning model

Surface Chemistry-Enhanced Wearable Biosensors: A Novel Approach for Non-Invasive Continuous Health Monitoring

With the rise of health concerns in recent years, wearable biosensors have gained widespread attention as an important technology for health monitoring. It can monitor human physiological indicators such as blood glucose and lactate. This type of monitoring does not require complex operations or frequent sampling and is non-invasive and capable of real-time monitoring. Chemically modified electrochemical biosensors have further improved the sensitivity and selectivity of monitoring and have the potential for a wider range of applications. In this paper, we will explore the application of surface chemically enhanced wearable sensors for non-invasive health monitoring and their future directions.

Investigating the suitability of the matched fiber Bragg grating approach for guided wave based structural health monitoring

Fiber Bragg grating (FBG) sensors are thought to be ideal sensors for structural health monitoring (SHM). Amplitude based techniques such as matched filters and the edge-filtering have been proposed to fulfill the high sampling rates necessary for guided waves (GW) sensing. The current research for the first time shows the inherent robustness the matched filter technique provides to the sensing system. The matched system is realized through a FBG deployed on a low cost micrometer screw gauge which allows flexibility in matching the reflected wavelengths of the FBGs. Based on the results it is shown that, in the remote configuration the matched FBG approach is robust under changing temperature conditions. This concept has been shown analytically and experimentally. Furthermore, the approach is then extended for multiplexing of the sensors and the deployed system is used for detecting and localizing damage in the plate.

Light‐Assisted Polyproton Dissociated PAAm‐PA Hydrogel‐Based Moisture‐Driven Electricity Generator with a Broad Operating Range

AbstractDue to its widespread availability and spontaneity, moisture electricity generation (MEG) holds unique advantages in self‐powered systems. However, it faces challenges, including the limitations of relying on a single kind of power generation and insufficient output performance. Inspired by the mechanisms of water absorption of plants, this paper explores a light‐moisture coordinated electricity generating hydrogel (L‐MEGH) device with flexible, scalable, and highly efficient energy conversion performance, which is obtained through the UV polymerization of hydrophilic acrylamide (AAM) and phytic acid (PA) in the presence of photosensitizers. The obtained hydrogel demonstrates superior moisture absorption and remarkable electricity generation stability across a range of humidity conditions. Notably, the open‐circuit voltage (Voc) of the L‐MEGH increased from 0.675 to 0.838 V after the addition of photosensitizers (Erythrosin B, E) (the significant enhancement, up to 24%), and the short‐circuit current (Isc) reaching 635.543 µA. This L‐MEGH can realize stable electrical output even under extreme temperatures, producing 0.5 V at −20 °C for 45 h. The scalable L‐MEGHs (connected on‐demand in series/parallel) can power various commercial electronics, including nighttime illumination, mobile phones, and health monitoring sensors. This work pioneers a sustainable power generation pathway capable of enhancing performance through the hybrid collection of multiple natural energy sources.

Heart Rate and Oxygen Saturation Internet of Things System (HROS-IoT) Uses Fuzzy Logic

Emergencies in hospitals, including in-hospital cardiac arrest (IHCA), necessitate effective response systems for monitoring vital signs such as heart rate and oxygen saturation. This study aims to develop and evaluate a Heart Rate and Oxygen Saturation Internet of Things (HROS-IoT) system utilizing the MAX30102 sensor and ESP32 microcontroller for real-time health monitoring. The system transmits data to the Blynk application via WiFi, enabling remote monitoring. Testing involved comparing the HROS-IoT system's performance against the commercial LK87 oximeter in measuring heart rate and oxygen saturation before and after meals with five participants. Results indicated that the HROS-IoT system produced heart rate measurements with an average error of 5.2 BPM before meals and 11.3 BPM after meals. Oxygen saturation readings showed an average error of 1% before meals and after meals. Despite minor discrepancies influenced by individual physiological differences and environmental conditions, the HROS-IoT system consistently delivered reliable data. The system's real-time monitoring capability and remote data access enhance proactive health management in hospitals. This study demonstrates the potential of the HROS-IoT system to improve patient outcomes and safety, suggesting further refinements for better accuracy and integration into healthcare settings.

High-Performance Supercapacitive Pressure Sensors via Height-Grading Micro-Domes of Ionic Conductive Elastomer.

Soft capacitive sensors present numerous appealing characteristics, including simple structure, low power consumption, and fast response. However, they often suffer from low sensitivity and a limited linear sensing range. Herein, a concept is presented to enhance the sensitivity and linearity of supercapacitive pressure sensors by functionally grading the heights of macrodomes constructed from a highly elastic and ionic conductive elastomer made of poly(vinyl alcohol) and phosphoric acid (PVA/H3PO4). The resultant supercapacitive sensors exhibit a high sensitivity (423.42 kPa-1), wide linear sensing range (0-400 kPa), ultralow limit of detection (0.48 Pa), and high durability (stable signal outputs up to 5000 cycles of loading/unloading). Additionally, the sensors can maintain consistent sensing performance within a temperature range of 25-40 °C. The potential of the sensor in health monitoring is demonstrated through ultrahigh-resolution weight measurement, pulse detection, and respiration monitoring.

Sustainable Engineering of the Wearable Sensor for Noninvasive Health Monitoring Using Exfoliated Layered Double Hydroxide/Reduced Graphene Oxide/Poly(vinyl alcohol) Electrospun Fiber Composites

Sustainable Engineering of the Wearable Sensor for Noninvasive Health Monitoring Using Exfoliated Layered Double Hydroxide/Reduced Graphene Oxide/Poly(vinyl alcohol) Electrospun Fiber Composites

Three-Dimensional Printing Limitations of Polymers Reinforced with Continuous Stainless Steel Fibres and Curvature Stiffness

This study investigates the printability limitations of 3D-printed continuous 316L stainless steel fibre-reinforced polymer composites obtained using the Materials Extrusion (MEX) technique. The objective was to better understand the geometric printing limitations of composites fabricated using continuous steel fibres, based on a combination of bending stiffness testing and piezoresistive property studies. The 0.5 mm composite filaments used in this study were obtained by co-extruding polylactic acid (PLA), with a 316 L stainless steel fibre (SSF) bundle. The composite printability limitations were evaluated by the printing of a series of ’teardrop’ shaped geometries with angles in the range from 5° to 90° and radii between 2 and 20 mm. The morphology and dimensional measurements of the resulting PLA-SSF prints were evaluated using μCT scanning, optical microscopy, and calliper measurements. Sample sets were compared and statistically examined to evaluate the repeatability, turning ability, and geometrical print limitations, along with dimensional fluctuations between designed and as-printed structures. Comparisons of the curvature bending stiffness were made with the PLA-only polymer and with 3D-printed nylon-reinforced short and long carbon fibre composites. It was demonstrated that the stainless steel composites exhibited an increase in bending stiffness at smaller radii. The change in piezoresistance response of the PLA-SSF with load applied during the curvature bending stiffness testing demonstrated that the 3D-printed composites may have the potential for use as structural health monitoring sensors.

Advanced Sensors and Sensing Systems for Structural Health Monitoring in Aerospace Composites

This review examines the state‐of‐the‐art sensors and sensing technologies employed for structural health monitoring (SHM) in aerospace composites, highlighting the shift from conventional nondestructive evaluation techniques to real‐time monitoring systems. The review discusses the challenges associated with composite materials, such as their anisotropic nature and susceptibility to invisible damage, and how these challenges have driven the improvement of SHM techniques. Fiber‐optic sensors, including interferometric, distributed, and grating‐based sensors, are analyzed for their high sensitivity and multiplexing capabilities, making them suitable for distributed sensing applications. Piezoelectric sensors are evaluated for their effectiveness in both active and passive damage detection methods. At the same time, piezoresistive self‐sensing systems are explored for their potential to integrate sensing directly into composite materials. The review also addresses the challenges encountered in implementing SHM systems. It suggests solutions like protective coatings, advanced data processing algorithms, and modular system design to overcome these challenges. In conclusion, this review provides a comprehensive overview of the current SHM technologies for aerospace composites, underscoring the need for sustained research and development to improve sensor technology, expand data processing capabilities, and ensure seamless integration with aircraft systems, thus contributing to the safety and efficiency of aerospace operations.

Fabrication of TPU-Supported Au-Bi2S3/Ti3C2Tx electrospun mat: Towards flexible and Multi-functional sensors for human motion and NH3 detection at room temperature

The potential applications of wearable sensors in health monitoring, micro-environment detection, and advanced soft electronic noses have attracted widespread attention. However, due to the inherent limitations of traditional organic flexible substrates, simultaneously achieving excellent flexibility, high sensitivity, robustness, and breathability remains a significant challenge. Herein, using the electrospinning method, a flexible TPU substrate film was prepared, and Bi2S3/Ti3C2Tx nanocomposite materials were synthesized through a simple one-step hydrothermal method. Au nanoparticles were attached to the surface of the composite material using sodium borohydride, and finally, the surface impregnation method was used to successfully prepare the Au-Bi2S3/Ti3C2Tx-TPU flexible electrospun mat. The as-prepared sensor demonstrated an outstanding response of 154 % to 100 ppm NH3 at room temperature, coupled with high selectivity, repeatability, and long-term stability. The strain properties of the sensor were also evaluated, showcasing its potential for human motion and physiological feature detection, such as breathing, swallowing, and limb movements. The study’s findings indicated that the Au-Bi2S3/Ti3C2Tx-TPU electrospun mat sensor has promising applications in flexible electronics, wearable environmental monitoring devices, and human healthy monitoring.

Using removable sensors in structural health monitoring: A Bayesian methodology for attachment-to-attachment uncertainty quantification

Structural responses are vulnerable to perturbations when subjected to variable environmental and operational conditions, thereby contributing to the slow uptake of Structural Health Monitoring (SHM) beyond academic research. More importantly, SHM systems using removable sensors face additional sensing variability due to the inherent uncertainty in sensor reattachment compared to permanently attached sensors. In this study, a novel probabilistic approach is developed for output-only damage detection utilizing ultrasonic guided waves. Experimental uncertainties and sensor attachment factors are simultaneously considered for the first time in a Bayesian context. The uncertainty introduced by reattached sensors is incorporated into the likelihood function in a comprehensive way. Bayesian model class selection using an adaptive sampling scheme is adopted to evaluate the evidence of discrete damage classes. A reference case to an aluminum plate with progressive notches is utilized to demonstrate the significant effects of attachment uncertainty on guided wave signals. The optimal data normalization model for guided wave processing under different attachment states is evaluated using the Mahalanobis distance. The notch length is identified accurately along with the uncertainty, even though the latent adhesive parameters cannot be estimated directly.

Self‐Powered and 3D Printable Soft Sensor for Human Health Monitoring, Object Recognition, and Contactless Hand Gesture Recognition

AbstractA new galvanic cell design of a self‐powered and 3D‐printable soft sensor showing health monitoring, object recognition, and contactless hand gesture recognition, is reported. The soft sensor consists of a 3D‐printed poly(acrylic acid) (PAA) hydrogel electrolyte layer, a soft anode layer, and a soft cathode layer. The anode layer is a 3D‐printed and Cu2+ cross‐linked poly(N,N‐dimethylacrylamide‐co‐3‐alanine‐2‐hydroxypropylmethacrylate) (PDA) hydrogel dispersed with Cu metal particles (PDA/Cu2+/Cu hydrogel), while the cathode layer is a bottom thin layer of the PAA hydrogel containing MnO2 (PAA/MnO2). Using graphite films as the soft electrodes, the soft sensor is finally assembled. The soft sensor has high force and temperature sensitivities. It gives different electric current responses under stretching, bending, pressing, and impact loading. The soft sensor is demonstrated to be useful in detecting human motion and physiological activities, e.g., breath. Based on the force and contactless temperature sensitivities, the soft sensor is used to recognize human hand gestures and plastic balls with different diameters. This 3D printable soft sensor with self‐powering, contactless motion capturing, and multi‐pimulus sensing capabilities illustrates a new pathway to make soft sensory devices for healthcare and human‐machine interaction applications.

Hierarchical Porous Biowaste‐Based Dual Humidity/Pressure Sensor for Robotic Tactile Sensing, Sustainable Health, and Environmental Monitoring

A crucial tradeoff between material efficacy and environmental impact is often encountered in the development of high‐performance sensors. The use of rare‐earth elements or intricate fabrication techniques is sometimes needed for conventional sensing materials, posing concerns regarding sustainability. Exploring the potential of tomato peel (TP) as a dual‐purpose sensing dielectric layer for pressure and humidity monitoring is a paradigm shift, capitalizing on its porous structure and hygroscopic nature. TP‐based humidity sensor (TP‐HS) exhibits impressive results, with a wide humidity sensing range (5%–95%), fast response/recovery time (6.5/9 s), a high sensitivity (12 500 pF %RH−1), and a high stability (30 days). Additionally, TP‐based pressure sensor (TP‐PS) also shows excellent performance in accurately sensing pressure changes in a wide range (0–196 kPa). TP‐HS can easily distinguish between breathing rates (normal, fast, and slow) and moisture content present in different moisturizers (aloe vera and sanitizer) along with its successful use for proximity sensing. Alternatively, TP‐PS demonstrates weight measurement (490 and 980 N), grip recognition (measuring the pressure exerted by each finger), and gesture detection (by monitoring multiple bending angles 0°, 30°, 50°, and 80°). A wearable, biocompatible dual sensor based on a promising sustainable material for environmental, robotic, and health monitoring applications is successfully demonstrated.

Hybrid multimodal wearable sensors for comprehensive health monitoring

Hybrid multimodal wearable sensors for comprehensive health monitoring