Wearable Health Monitoring Devices Research Articles

Trimodal Watch-Type Wearable Health Monitoring Device

In the domain of healthcare, wearable health monitoring devices have emerged as essential tools for the advancement of patient health tracking. These devices facilitate the provision of real-time medical data to clinicians, enabling early diagnosis, timely intervention, and enhanced management of individual health. This study introduces an innovative trimodal wearable health monitoring device in the form of a wristwatch. The device integrates a breath analyzer for the assessment of gaseous phase biomarkers, a sweat analyzer for the evaluation of aqueous-phase biomarkers, and an infrared sensor for the measurement of body temperature in the optical phase. Engineered on a compact 3 cm × 3 cm printed circuit board, the device has been optimized for wearability, power efficiency, and seamless integration with both wired and wireless charging and communication systems. Furthermore, custom software applications, designed for both Windows and Android platforms, have been developed to facilitate intuitive data visualization and storage on personal computers and smartphones. Empirical results from real-time chemical testing substantiate the device’s efficacy and potential as an advanced solution for wearable health monitoring.

High-performance Waterproof Flexible Thermoelectric Generators for Self-powered Electronics

Flexible and wearable thermoelectric generators (TEG) have emerged as promising energy sources for wearable health-monitoring devices. However, common thermoelectric generators are difficult to be applied to a wide range of application scenarios due to their poor durability, low output power, and susceptibility to human sweat or underwater environments. Here, we propose a waterproof wearable TEG with a gap structure. Through structural optimization and full-coverage elastomer encapsulation, the wearable TEG has a maximum power density of 4.38mW∙cm-2 at a temperature difference (ΔT) of 30K and exhibits good stability under aqueous environments, which is capable of supplying power to electronic devices even under submerged conditions. The internal resistance of wearable TEG changes by less than 10% at 50% stretch or 900 degrees of torsion, showing good flexibility and mechanical stability. Based on this, we designed an energy harvesting and management system to help wearable TEG collect and utilize energy on demand, and successfully implemented wireless transmission of human skin temperature data for underwater environments and real-time electrocardiograms (ECG) tests for health detection in air environments. This research provides a reliable method for powering wearable electronic devices using thermoelectric generators.

Three-dimensional interconnected nanofiber network derived from bacterial cellulose for strain sensing and energy harvesting

Flexible strain sensors have garnered widespread attention due to their potential applications, including human health monitoring, human-machine interfaces and intelligent robotics. However, the tradeoff between sensitivity and detection range needs to be considered. Herein, a dual-functional film based on bacterial cellulose is fabricated with a cost-effective freeze-drying and carbonization process, which is used for strain sensing and energy harvesting. The effect of the carbonization temperature on the structure is explored. Taking advantage of three-dimensional interconnected nanofiber of carbonized bacterial cellulose (CBC) network and the stretchability of the Ecoflex substrate, the optimized sensor demonstrates impressive strain sensing capabilities, featuring exceptional sensitivity (gauge factor = 100), large tolerable strain (100 %), swift response time (70 ms), and robust durability (3000 cycles). These features endow the CBC strain sensor with the capability to effectively discern and monitor multiple complex human activities, such as pulse rate and various human movements. Moreover, the CBC structure can serve as triboelectric nanogenerator (TENG) for energy harvesting. This work provides a green, efficient and cost-effective manufacturing method for the development of multifaceted wearable devices for human health monitoring and portable energy sources.

Wearable broadband MoS2 photodetector for dual heart rate and UV detection powered by PDMS-MXene TENG

Wearable electronic devices capable of monitoring health parameters and environmental factors are tremendously desirable. Environmental energy harvesting as a power source is crucial to replace traditional batteries. This study aims to contribute to the development of sustainable and efficient wearable devices for health monitoring and environmental sensing. In this study, a self-powered wearable MoS2-based photodetector, integrated with a PDMS-MXene-based triboelectric nanogenerator (TENG) is presented. The TENG generates isometric AC voltage using a diode, and it is used to charge a capacitor for DC voltage output. The photodetector, with a responsivity of 1.25 × 105A/W, specific detectivity of 2×1013 Jones, millisecond response time, enhanced responsivity of 1.1×1010 V/W and specific detectivity of 9.5×1016 Jones while coupled with TENG, successfully measured heart rate using a 660 nm LED and compared well with a commercial pulse meter. Additionally, UV illumination was detected using a 395 nm LED in the AC mode of the TENG. The study’s results support the advancement of flexible, integrated, and sustainable wearable devices, offering solutions to challenges posed by current battery-powered devices.

Buckling-inspired triboelectric sensor for multifunctional sensing of soft robotics and wearable devices

Amidst the rapid development of intelligent robotics and wearable health monitoring devices, there is an urgent demand for flexible sensor with high sensitivity and precise feedback. In this paper, a multifunctional triboelectric sensor inspired by the phenomenon of buckling is introduced, which integrates kirigami structures with triboelectric nanogenerator principles to accurately detect one-dimensional (1D) and two-dimensional (2D) deformations. The sensor employs a contact-separating structure, with its friction layers consisting of 2D laser-cut kirigami electrodes, which deform into three-dimensional (3D) structures through tensile or compressive buckling. The tensile buckling sensor (BS) developed is capable of sensing the bending angle of soft grippers, allowing the detection of the size of grasped objects with a high recognition rate of 93.75 %. Additionally, in its 1D compressive buckling form, the sensor can be used to recognize various human motion patterns effectively, while the 2D compressive version can be used to measure the expansion of curved surfaces with a sensitivity of 1.3307 V/mm. By combining the unique properties of buckling structures, the innovative triboelectric multifunctional sensor proposed offers a new solution for high-precision motion feedback control with potential application in soft robotics and health monitoring.

Advances in Portable and Wearable Acoustic Sensing Devices for Human Health Monitoring.

The practice of auscultation, interpreting body sounds to assess organ health, has greatly benefited from technological advancements in sensing and electronics. The advent of portable and wearable acoustic sensing devices marks a significant milestone in telemedicine, home health, and clinical diagnostics. This review summarises the contemporary advancements in acoustic sensing devices, categorized based on varied sensing principles, including capacitive, piezoelectric, and triboelectric mechanisms. Some representative acoustic sensing devices are introduced from the perspective of portability and wearability. Additionally, the characteristics of sound signals from different human organs and practical applications of acoustic sensing devices are exemplified. Challenges and prospective trends in portable and wearable acoustic sensors are also discussed, providing insights into future research directions.

Self-powered sensing platform for monitoring uric acid in sweat using cobalt nanocrystal-graphene quantum dot-Ti3C2TX monolithic film electrode with excellent supercapacitor and sensing behavior.

Thesynthesis of cobalt nanocrystal-graphene quantum dot-Ti3C2TX monolithic film electrode (Co-GQD-Ti3C2TX) is reportedvia self-assembly of Ti3C2TX nanosheets induced by protonated arginine-functionalized graphene quantum dot and subsequent reduction of cobalt (III). The resulting Co-GQD-Ti3C2TX shows good monolithic architecture, mechanical property, dispersibility and conductivity. The structure achieves excellent supercapacitor and sensing behavior. The self-charging supercapacitor produced by printing viscous Co-GQD-Ti3C2TX hydrogel on theback of flexible solar cell surfaceprovides high specific capacitance (296 F g-1 at 1 A g-1), high-rate capacity (153 F g-1 at 20 A g-1), capacity retention (98.1% over 10,000-cycle) and energy density (29.6 W h kg-1 at 299.9 W kg-1). The electrochemical chip produced by printing Co-GQD-Ti3C2TX hydrogel on paper exhibits sensitive electrochemical response towards uric acid. The increase of uric acid between 0.01 and 800μM causes a linear increase in differential pulse voltammetry signal with adetection limit of 0.0032μM. The self-powered sensing platform integrating self-charging supercapacitor, electrochemical chip and micro electrochemical workstation was contentedly applied to monitoring uric acid in sweats and shows one broad application prospect in wearable electronic health monitoring device.

Highly Stretchable, Tissue-like Ag Nanowire-Enhanced Ionogel Nanocomposites as an Ionogel-Based Wearable Sensor for Body Motion Monitoring.

The development of wearable electronic devices for human health monitoring requires materials with high mechanical performance and sensitivity. In this study, we present a novel transparent tissue-like ionogel-based wearable sensor based on silver nanowire-reinforced ionogel nanocomposites, P(AAm-co-AA) ionogel-Ag NWs composite. The composite exhibits a high stretchability of 605% strain and a moderate fracture stress of about 377 kPa. The sensor also demonstrates a sensitive response to temperature changes and electrostatic adsorption. By encapsulating the nanocomposite in a polyurethane transparent film dressing, we address issues such as skin irritation and enable multidirectional stretching. Measuring resistive changes of the ionogel nanocomposite in response to corresponding strain changes enables its utility as a highly stretchable wearable sensor with excellent performance in sensitivity, stability, and repeatability. The fabricated pressure sensor array exhibits great proficiency in stress distribution, capacitance sensing, and discernment of fluctuations in both external electric fields and stress. Our findings suggest that this material holds promise for applications in wearable and flexible strain sensors, temperature sensors, pressure sensors, and actuators.

A signal-adaptive measurement matrix construction algorithm for compressed sensing of sEMG data

Abstract Surface electromyography (sEMG), serving as a pivotal wearable technology, is a promising tool to assess and monitor muscle function. Yet, the efficacy of a sEMG system faces inevitable constraints, primarily stemming from the challenges of transmission and energy consumption induced by big data. Compressed sensing (CS) is a promising data acquisition solution that takes advantage of the signal sparseness in a particular basis to significantly reduce the number of samples. Current CS methods usually employ random or deterministic measurement matrix to compress sEMG signal. However, these measurement matrices do not integrate the signal feature, which limits the performance of these CS methods. To address this problem, this paper proposes an improved CS method for sEMG data compression. This proposed method introduces a measurement matrix construction algorithm to produce a deterministic matrix tailored for processing sEMG signals. The deterministic measurement matrix integrates the characteristics of the magnitudes of sEMG signals. The sEMG signals acquired from the upper limb muscles of the stroke survivors were applied to evaluate the proposed CS method, with results showing that it achieves better reconstruction accuracy and robustness than the CS methods with other measurement matrices. The proposed method employing basis pursuit (BP) in the signal reconstruction presents better performance than that employing orthogonal matching pursuit (OMP). Hence, we can conclude that the proposed CS algorithm is of key importance for the popularization of sEMG in the wearable health monitoring devices.

A Novel Instruction Driven 1-D CNN Processor for ECG Classification.

Electrocardiography (ECG) has emerged as a ubiquitous diagnostic tool for the identification and characterization of diverse cardiovascular pathologies. Wearable health monitoring devices, equipped with on-device biomedical artificial intelligence (AI) processors, have revolutionized the acquisition, analysis, and interpretation of ECG data. However, these systems necessitate AI processors that exhibit flexible configuration, facilitate portability, and demonstrate optimal performance in terms of power consumption and latency for the realization of various functionalities. To address these challenges, this study proposes an instruction-driven convolutional neural network (CNN) processor. This processor incorporates three key features: (1) An instruction-driven CNN processor to support versatile ECG-based application. (2) A Processing element (PE) array design that simultaneously considers parallelism and data reuse. (3) An activation unit based on the CORDIC algorithm, supporting both Tanh and Sigmoid computations. The design has been implemented using 110 nm CMOS process technology, occupying a die area of 1.35 mm2 with 12.94 µW power consumption. It has been demonstrated with two typical ECG AI applications, including two-class (i.e., normal/abnormal) classification and five-class classification. The proposed 1-D CNN algorithm performs with a 97.95% accuracy for the two-class classification and 97.9% for the five-class classification, respectively.

“Whispers from the Wrist”: Wearable Health Monitoring Devices and Privacy Regulations in the U.S.: The Loopholes, the Challenges, and the Opportunities

The growth of wearable technology has enabled the collection of even more personalized information on individuals. New health-related devices marketed to consumers collect health information that might not fall under the traditional category of Protected Health Information, and thus, HIPAA protections do not fully apply. Meaning, commercial wearable health devices do not fall under FDA oversight, and data not paired with a doctor–patient relationship do not fall under HIPAA privacy protection; thus, much of the gathered health-related metrics are left without regulation and open to be sold to data brokers. As such, these data can be leveraged by health insurance, law enforcement, and employers, to name a few. This manuscript explores the loopholes in current regulations and suggests a framework that categorizes wearable data and addresses challenges in data transfer. Furthermore, taking a user perspective, the suggested framework offers solutions that aim to guide users and policymakers in navigating privacy issues in wearable technology.

The Intersection of Plastic Electronics and Medical Innovation

The aging global population has catalyzed a paradigm shift in healthcare, emphasizing disease prevention over treatment and underscoring the need for large-scale, long-term monitoring of physiological parameters. Wearable health monitoring devices have emerged as a pivotal solution, offering real-time physiological data collection across prevention, treatment, and rehabilitation phases, thus revolutionizing traditional health monitoring approaches. This paper explores the integration of advanced materials—conductive polymers, flexible carbon nanomaterial electrodes, and metal foil substrates—into wearable health technologies. These materials enhance device flexibility, biocompatibility, and non-intrusive monitoring capabilities, providing medical-grade data crucial for early diagnosis and treatment guidance. With the wearable device market projected to expand significantly, fueled by the Internet of Things (IoT) and device miniaturization, this study delves into the technological advancements in detection technologies for electrophysiological, physical, biochemical, and photoelectric signals. It also examines the challenges and future directions in wearable health devices, focusing on material innovation, device miniaturization, and the integration of plastic electronics to improve wearability, sustainability, and interactivity. Through systematic analysis, this paper aims to highlight the transformative impact of wearable health technologies on enhancing patient care, facilitating early disease detection, and offering personalized health management solutions.

A Reconfigurable Nonvolatile Memory Architecture for Prolonged Wearable Health Monitoring Devices

A Reconfigurable Nonvolatile Memory Architecture for Prolonged Wearable Health Monitoring Devices

Bio-Electronics Interface between Electronics and Biological Systems for Healthcare Applications.

The intersection of electronics and biology has led to the emergence of bio-electronics interfaces, which hold tremendous potential for revolutionizing healthcare applications. These interfaces facilitate seamless communication between electronic devices and biological systems, enabling a range of diagnostic, therapeutic, and monitoring capabilities with unprecedented precision and efficiency.This paper provides a comprehensive overview of the recent advancements in bio-electronics interfaces and their diverse applications in healthcare. The fundamental principles underlying the integration of electronics with biological systems, including the design and fabrication of bio-compatible materials, signal transduction mechanisms, and biointegration strategies are discussed. [1] The paper discusses specific healthcare applications enabled by bio-electronics interfaces, such as bio-sensing for disease diagnosis, neural interfaces for brain-machine communication and prosthetics, bio-electronic implants for targeted drug delivery and neuromodulation, and wearable devices for continuous health monitoring. We also examine the challenges and opportunities associated with the development and implementation of bio-electronics interfaces in healthcare settings. These challenges include biocompatibility issues, signal interference, power management, data security, and regulatory considerations. However, rapid advancements in materials science, microfabrication techniques, wireless communication, and machine learning are driving innovation and overcoming these hurdles. We highlight the potential of bio-electronics interfaces to transform personalized medicine by enabling real-time monitoring of physiological parameters, early detection of diseases, and personalized therapeutic interventions tailored to individual patients' needs. By integrating electronic devices with biological systems at the molecular, cellular, and organismal levels, bio-electronics interfaces have the potential to revolutionize healthcare delivery, improve patient outcomes, and enhance quality of life.

Impact of Bio-impedance Emitted from Wearable Smart Watches on Skin Microbiota: A Pilot Study

ABSTRACT Smart watches (SWs), which offer users a variety of features including bio-impedance measurements, have grown significantly in popularity as wearable health monitoring devices. Electrical currents are used in bio-impedance technology to measure things like body composition and hydration levels. However, little is known about how these electrical currents might affect the skin’s microbiota, which is vital for preserving skin health. This summary of the possible effects of bio-impedance measurements from SWs on the skin microbiota is intended. Hence, we tried to explore the effect of impedance emitted from smart watches on the skin microbiota. A total of 20 volunteers were recruited, and their skin microbial load was enumerated from the impedance-exposed region at two different time intervals and compared with non-exposed region. We found an overall 57% reduction of microbial load on impedance-exposed regions as compared to non-exposed regions. Impedance significantly (P < 0.0001) reduced the microbial load. Despite preliminary data pointing to a potential connection between bio-impedance readings from SWs and skin microbiota, further research is required to understand the impact of SWs on the human skin.

Extrusion-based additive manufacturing of aluminium-filled ethylene vinyl acetate for electrically conductive 3D part printing

Addition of carbon-based fillers to enhance electrical conductivity is quite popular but addition of metal fillers is still a challenge due to oxidation and unavailability of metal nano-powders. In this paper, fabrication of flexible electrically conductive parts is proposed using aluminium metal powder as filler material. Aluminium metal powder is mixed with ethylene vinyl acetate (EVA) by chemical mixing process. Cyclohexane is used as a mixing medium in which EVA is dissolved and aluminium powder is added by weight. An in-house developed material extrusion tool mounted on CNC milling machine is used for printing of flexible electrically conductive samples. Pellet-based extrusion process is used for printing flexible parts as conventional filament-based 3D is not suitable due to buckling. Composite with filler loading in 5%, 10%, 20% and 30% were made and samples were printed. Investigations were made on printability of composite and its electrical conductivity. The aluminium fillers presence and dispersion in polymer were ensured. The samples were printed in temperature range of 130–140 °C through 0.4 mm diameter nozzle. It was found that the resistivity drops by around 60% on varying the filler concentration from 20% to 30%; 81.6 kΩ is the lowest resistance observed with 30% filler concentration. A simulation study on thermal behaviour of material extrusion tool has been done and is validated practically. The application of flexible electrically conductive parts lies in fabrication of various electronic devices like antenna, display boards, solar panels, and wearable health monitoring devices.

Acoustic wave devices based on piezoelectric/ferroelectric thin films for high-frequency communication systems and sensing applications

Surface acoustic wave (SAW) and bulk acoustic wave (BAW) based radio-frequency (RF) filters dominate in handsets markets mainly because they have miniature size so multiple filters can be used but take up very small board area. Besides, due to their inherent advantages, such as low insertion loss, relatively high resonant frequency, and miniature size, their application in the physical and biochemical sensing fields has also gradually expanded. The successful implementation requires specific knowledge of acoustic wave properties, the working mechanisms, material properties, and device design. So, in this review, we survey the SAW and BAW filter technology by discussing the working principles and the comparison between the operation frequency band allocations. In addition, the approaches to enhance the performance including the selection of single crystal/ferroelectric materials for BAW and the structure design optimization for SAW are introduced with discussions for further improvement. Then, flexible SAW and BAW devices are also presented and their new application opportunities in the fields of skin-like electronics and wearable health monitoring devices can be foreseen. Finally, the potential challenges of high frequency, wide bandwidth, miniaturization, and compatibility with the integrated circuits (IC) manufacturing process are overviewed as well.

Wearable Sweat Management Technologies

AbstractThe aging population and increasing prevalence of diseases among younger individuals have heightened the pressing demand for wearable health monitoring devices among the general public. In comparison to self‐health monitoring at physical signal level, wearable biochemical monitoring can provide more comprehensive and insightful information regarding one's own health status. Wearable sweat‐sensing technologies hold great potential for non‐invasive and continuous biochemical monitoring, and have emerged as a focal point of wearable health monitoring research. The effective management of sweat, encompassing convenient induction, reliable collection, and efficient flow control and storage, is fundamental in wearable sweat sensing. To elucidate the research progression in these aspects, this review first summarizes sweat secretion mechanisms, induction method, and sampling mode. Additionally, detailed summaries and discussion on sweat sampling and transport modes are provided. Furthermore, within the context of epidermal microfluidics, the technologies on sweat flow control and storage management based on microvalves are discussed. Lastly, current commercialization and key challenges are summarized.

Optimization of low power consumption in wearable health monitoring devices and algorithm design

This paper surveys state-of-the-art approaches designed to decrease the power consumption of wearable health monitoring devices, thereby optimizing battery life. Specifically, this paper examines a concept proposed by researchers in a separate investigation, which involves active computation offloading. This entails developing an algorithm that efficiently distributes data processing tasks between wearable health monitoring devices and mobile applications. Researchers have successfully reduced system power consumption by up to 20% by intelligently offloading computations based on existing device characteristics. In contrast, another ECG remote monitoring system focuses on designing the lowest power sensor while keeping the system low cost and scalable. Lastly, this paper provides ideas to further lower power by state-of-the-art chip design, algorithmic and system design techniques.

Interface‐Confined Assembly of Layered Molecular Crystal Arrays Toward Wearable UV‐Radiation Monitor

AbstractOrganic semiconductors have significant potential for wearable optoelectronics due to their designable molecular structures, tunable photoelectronic properties, and flexibility. For their integration into optoelectronic devices, organic semiconductors need to be assembled into single‐crystalline arrays with both precise alignment of micro‐/nanostructures and long‐range order of molecules. In this study, an interface‐confined lithography technique is developed for fabricating organic single‐crystalline microwire arrays with layered molecular stacking and ordered crystallographic orientation toward wearable UV radiation monitor. This interface‐confined strategy introduces parallel gas–liquid–solid three‐phase contact line (TPCL) arrays to suppress the lateral growth of single crystals. Meanwhile, TPCLs with controlled dewetting direction promote longitudinal growth, thus universally yielding 1D arrays based on various organic semiconducting small molecules. These 1D single‐crystalline arrays exhibit high average mobility of 12.5 cm2 V−1 s−1 with uniform electronic properties of 9.3% variation, and good mechanical stability after 1000 bending times. Based on organic 1D arrays, wearable devices with robust photoresponsivity of 8.26 × 103 A W−1 and high mechanical flexibility achieve real‐time monitoring of UV radiation to prevent skin disease. This confined‐assembly strategy opens a new avenue to construct wearable optoelectronic devices for health monitoring.