Future Wearables Research Articles

Stretchable and Breathable Electroluminescent Displays Based on Ultrathin Nanocomposite Designs.

Stretchable electroluminescent devices represent an emerging optoelectronic technology for future wearables. However, their typical construction on sub-millimeter-thick elastomers has limited moisture permeability, leading to discomfort during long-term skin attachment. Although breathable textile displays may partially address this issue, they often have distinct visual appearances with discrete emissions from fibers or fiber junctions. This study introduces a convenient procedure to create stretchable, permeable displays with continuous luminous patterns. The design utilizes ultrathin nanocomposite devices embedded in a porous elastomeric microfoam to achieve high moisture permeability. These displays also exhibit excellent deformability, low-voltage operation, and excellent durability. Additionally, the device is decorated with fluorinated silica nanoparticles to achieve self-cleaning and washable capabilities. The practical implementation of these nanocomposite devices is demonstrated by creating an epidermal counter display that allows intimate integration with the human body. These developments provide an effective design of stretchable and breathable displays for comfortable wearing.

Knot Architecture for Biocompatible and Semiconducting 2D Electronic Fiber Transistors.

Wearable devices have generally been rigid due to their reliance on silicon-based technologies, while future wearables will utilize flexible components for example transistors within microprocessors to manage data. Two-dimensional (2D) semiconducting flakes have yet to be investigated in fiber transistors but can offer a route toward high-mobility, biocompatible, and flexible fiber-based devices. Here, the electrochemical exfoliation of semiconducting 2D flakes of tungsten diselenide (WSe2) and molybdenum disulfide (MoS2) is shown to achieve homogeneous coatings onto the surface of polyester fibers. The high aspect ratio (>100) of the flake yields aligned and conformal flake-to-flake junctions on polyester fibers enabling transistors with mobilities μ ≈1 cm2 V-1 s-1 and a current on/off ratio, Ion/Ioff ≈102-104. Furthermore, the cytotoxic effects of the MoS2 and WSe2 flakes with human keratinocyte cells are investigated and found to be biocompatible. As an additional step, a unique transistor 'knot' architecture is created by leveraging the fiber diameter to establish the length of the transistor channel, facilitating a route to scale down transistor channel dimensions (≈100 µm) and utilize it to make a MoS2 fiber transistor with a human hair that achieves mobilities as high as μ ≈15 cm2 V-1 s-1.

Flexible Thermoelectric Devices with Flexible Heatsinks of Phase-Change Materials and Stretchable Interconnectors of Semi-Liquid Metals.

Flexible thermoelectric (TE) devices offer great potential for wearable thermal management and self-powered systems, but heat dissipation and electrical interconnection remain key challenges. In this study, we address these issues by integrating flexible TE devices with phase-change material (PCM) heatsinks and stretchable semi-liquid metal (semi-LM) interconnectors. The effectiveness of PCMs with varying melting points for temperature regulation in different environmental conditions is demonstrated, delivering cooling effects exceeding 10 °C. Furthermore, the utilization of semi-LMs instead of LMs enables excellent stretchability and efficient heat dissipation. Moreover, the TE devices generate power with a density of 7.3 μW/cm2 at an ambient temperature of 22 °C, making it an ideal power source for a wearable self-powered sensing system. Successful integration into garments and armbands confirms the practicality and adaptability of these flexible thermoelectric devices, establishing them as critical components for future wearables with superior resilience to daily wear and tear.

High heat storing and thermally diffusive artificial skin for wearable thermal management

Thermal management for wearable devices is of great importance since heat generation from electronic devices can cause adverse effects such as skin burns and malfunctioning of the devices. Here, we present an advanced thermal skin (ATS) based on a hybrid structure that exhibits both high thermal diffusivity and thermal storage capability. Silver flake/polydimethylsiloxane (PDMS) serpentine structure (SPS) and sodium-acetate-based hydrogel matrix (SAHM) form an interfacial layer between the skin and wearable device not only to thermally protect the skin but also to prevent the device from malfunctioning by absorbing the heat released from the device. The high thermal diffusivity of SPS serves to spread the heat, while the high thermal storage capability of SAHM facilitates heat absorption without a significant temperature increase. Unlike the general phase change materials (PCMs), SAHM retains a small modulus change of 4.8 fold while maintaining comparable heat capacity to paraffin. Such a skin-like softness of ATS regardless of its phase has not yet been reported elsewhere to the authors’ best knowledge. This property enables conformal contact with the deformable surface and increases its applicability to wearable thermal management, and in this regard, we expect that this study will make significant contributions to the heat management of future wearables.

Engineering the Comfort‐of‐Wear for Next Generation Wearables

AbstractWearable technologies are becoming important for the fields of information technology and healthcare, driven mainly by societal issues such as the aging society and the current pandemic. Recently developed flexible/stretchable wearable devices have demonstrated their ability for long‐term healthcare monitoring with improved signal integrity and multimodality. However, the adherence of wearers to such wearable devices cannot be determined only by the function. Here “comfort‐of‐wear” is identified as one of the most critical parameters for future wearables, similar to how clothes are chosen based on how comfortable they are. “Comfort‐of‐wear” is defined as the device's ability to not to disturb the wearers’ daily life. Several engineering approaches are introduced to improve the comfort‐of‐wear of devices—via strategies that include improving flexibility by utilizing a combination of structures, materials, and systems. Finally, the future of wearables enabled by cutting‐edge advanced electronic technologies is proposed.

Logic-enabled textiles

Textiles hold great promise as a soft yet durable material for building comfortable robotic wearables and assistive devices at low cost. Nevertheless, the development of smart wearables composed entirely of textiles has been hindered by the lack of a viable sheet-based logic architecture that can be implemented using conventional fabric materials and textile manufacturing processes. Here, we develop a fully textile platform for embedding pneumatic digital logic in wearable devices. Our logic-enabled textiles support combinational and sequential logic functions, onboard memory storage, user interaction, and direct interfacing with pneumatic actuators. In addition, they are designed to be lightweight, easily integrable into regular clothing, made using scalable fabrication techniques, and durable enough to withstand everyday use. We demonstrate a textile computer capable of input-driven digital logic for controlling untethered wearable robots that assist users with functional limitations. Our logic platform will facilitate the emergence of future wearables powered by embedded fluidic logic that fully leverage the innate advantages of their textile construction.

On-skin ultrathin and stretchable multifunctional sensor for smart healthcare wearables

The flexible and stretchable multifunctional sensors for the precise monitoring of the human physiological health indicators is an emerging requirement of next-generation electronics. However, the integration of multifunctional sensors into a common substrate for simultaneous detection of such signals without interfering with each other is the most challenging work. Here, we propose MXene-Ti3C2Tx and 3, 4-ethylene dioxythiophene (EDOT) deposited on laser-induced graphene (LIG/MXene-Ti3C2Tx@EDOT) composite-based flexible and stretchable multifunctional sensors for strain, temperature, and electrocardiogram (ECG) monitoring. In-situ electrophoretic deposition (EPD) of MXene-Ti3C2Tx@EDOT composite into LIG outperforms high strain sensitivity of 2,075, temperature coefficient of resistance (TCR) of 0.86%, and low skin-contact impedance. The sensor platform is integrated into an ultrathin and highly resilient polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS). Finally, we demonstrate on-site detection of human body-induced deformations and physiological health indicators, such as temperature and ECG. The proposed approach paves a promising route to future wearables for smart skin and healthcare applications.

Screen Printing Carbon Nanotubes Textiles Antennas for Smart Wearables.

Electronic textiles have become a dynamic research field in recent decades, attracting attention to smart wearables to develop and integrate electronic devices onto clothing. Combining traditional screen-printing techniques with novel nanocarbon-based inks offers seamless integration of flexible and conformal antenna patterns onto fabric substrates with a minimum weight penalty and haptic disruption. In this study, two different fabric-based antenna designs called PICA and LOOP were fabricated through a scalable screen-printing process by tuning the conductive ink formulations accompanied by cellulose nanocrystals. The printing process was controlled and monitored by revealing the relationship between the textiles’ nature and conducting nano-ink. The fabric prototypes were tested in dynamic environments mimicking complex real-life situations, such as being in proximity to a human body, and being affected by wrinkling, bending, and fabric care such as washing or ironing. Both computational and experimental on-and-off-body antenna gain results acknowledged the potential of tunable material systems complimenting traditional printing techniques for smart sensing technology as a plausible pathway for future wearables.

Photoplethysmography in Normal and Pathological Sleep.

This article presents an overview of the advancements that have been made in the use of photoplethysmography (PPG) for unobtrusive sleep studies. PPG is included in the quickly evolving and very popular landscape of wearables but has specific interesting properties, particularly the ability to capture the modulation of the autonomic nervous system during sleep. Recent advances have been made in PPG signal acquisition and processing, including coupling it with accelerometry in order to construct hypnograms in normal and pathologic sleep and also to detect sleep-disordered breathing (SDB). The limitations of PPG (e.g., oxymetry signal failure, motion artefacts, signal processing) are reviewed as well as technical solutions to overcome these issues. The potential medical applications of PPG are numerous, including home-based detection of SDB (for triage purposes), and long-term monitoring of insomnia, circadian rhythm sleep disorders (to assess treatment effects), and treated SDB (to ensure disease control). New contact sensor combinations to improve future wearables seem promising, particularly tools that allow for the assessment of brain activity. In this way, in-ear EEG combined with PPG and actigraphy could be an interesting focus for future research.

Wearable Devices in Health Monitoring from the Environmental towards Multiple Domains: A Survey.

The World Health Organization (WHO) recognizes the environmental, behavioral, physiological, and psychological domains that impact adversely human health, well-being, and quality of life (QoL) in general. The environmental domain has significant interaction with the others. With respect to proactive and personalized medicine and the Internet of medical things (IoMT), wearables are most important for continuous health monitoring. In this work, we analyze wearables in healthcare from a perspective of innovation by categorizing them according to the four domains. Furthermore, we consider the mode of wearability, costs, and prolonged monitoring. We identify features and investigate the wearable devices in the terms of sampling rate, resolution, data usage (propagation), and data transmission. We also investigate applications of wearable devices. Web of Science, Scopus, PubMed, IEEE Xplore, and ACM Library delivered wearables that we require to monitor at least one environmental parameter, e.g., a pollutant. According to the number of domains, from which the wearables record data, we identify groups: G1, environmental parameters only; G2, environmental and behavioral parameters; G3, environmental, behavioral, and physiological parameters; and G4 parameters from all domains. In total, we included 53 devices of which 35, 9, 9, and 0 belong to G1, G2, G3, and G4, respectively. Furthermore, 32, 11, 7, and 5 wearables are applied in general health and well-being monitoring, specific diagnostics, disease management, and non-medical. We further propose customized and quantified output for future wearables from both, the perspectives of users, as well as physicians. Our study shows a shift of wearable devices towards disease management and particular applications. It also indicates the significant role of wearables in proactive healthcare, having capability of creating big data and linking to external healthcare systems for real-time monitoring and care delivery at the point of perception.

Compact Source-Gated Transistor Analog Circuits for Ubiquitous Sensors

Silicon-based digital electronics have evolved over decades through an aggressive scaling process following Moore's law with increasingly complex device structures. Simultaneously, large-area electronics have continued to rely on the same field-effect transistor structure with minimal evolution. This limitation has resulted in less than ideal circuit designs, with increased complexity to account for shortcomings in material properties and process control. At present, this situation is holding back the development of novel systems required for printed and flexible electronic applications beyond the Internet of Things. In this work we demonstrate the opportunity offered by the source-gated transistor's unique properties for low-cost, highly functional large-area applications in two extremely compact circuit blocks. Polysilicon common-source amplifiers show 49 dB gain, the highest reported for a two-transistor unipolar circuit. Current mirrors fabricated in polysilicon and InGaZnO have, in addition to excellent current copying performance, the ability to control the temperature dependence (degrees of positive, neutral or negative) of output current solely by choice of relative transistor geometry, giving further flexibility to the design engineer. Application examples are proposed, including local amplification of sensor output for improved signal integrity, as well as temperature-regulated delay stages and timing circuits for homeostatic operation in future wearables. Numerous applications will benefit from these highly competitive compact circuit designs with robust performance, improved energy efficiency and tolerance to geometrical variations: sensor front-ends, temperature sensors, pixel drivers, bias analog blocks and high-gain amplifiers.

Piezo-Sensitive Fabrics from Carbon Black Containing Conductive Cellulose Fibres for Flexible Pressure Sensors.

The design of flexible sensors which can be incorporated in textile structures is of decisive importance for the future development of wearables. In addition to their technical functionality, the materials chosen to construct the sensor should be nontoxic, affordable, and compatible with future recycling. Conductive fibres were produced by incorporation of carbon black into regenerated cellulose fibres. By incorporation of 23 wt.% and 27 wt.% carbon black, the surface resistance of the fibres reduced from 1.3 × 1010 Ω·cm for standard viscose fibres to 2.7 × 103 and 475 Ω·cm, respectively. Fibre tenacity reduced to 30–50% of a standard viscose; however, it was sufficient to allow processing of the material in standard textile operations. A fibre blend of the conductive viscose fibres with polyester fibres was used to produce a needle-punched nonwoven material with piezo-electric properties, which was used as a pressure sensor in the very low pressure range of 400–1000 Pa. The durability of the sensor was demonstrated in repetitive load/relaxation cycles. As a regenerated cellulose fibre, the carbon-black-incorporated cellulose fibre is compatible with standard textile processing operations and, thus, will be of high interest as a functional element in future wearables.

Wearable 3-Lead Electrocardiogram Placement Model for Fleet Sizing of Medical Devices.

BACKGROUND: Electrocardiography (ECG) provides valuable information on astronaut physiological and psychological health. ECG monitoring has been conducted during crewed missions since the beginning of human spaceflight and will continue during astronauts upcoming long-duration exploration missions (LDEMs) in support of automated health monitoring systems. ECG monitoring is traditionally performed in clinical environments with single-use, adhesive electrodes in a 3, 6, or 12-lead configuration placed by a trained clinician. In the space exploration environment, astronauts self-place electrodes without professional assistance. Wearable ECG systems are an attractive option for automated health monitoring, but electrode placement has not been quantified to a high enough degree to avoid artifacts within the data due to position changes. This variability presents challenges for physician-limited, autonomous health monitoring, so quantifying electrode placement is key in the development of reliable, wearable ECG monitoring systems.METHODS: We present a method of quantifying electrode placement for 3-lead, chest-mounted ECG using easy-to-measure, two-dimensional chest measurements.RESULTS: We find that male and female dimensions require different electrode positioning computations, but there is overlap in positioning between men and women. The distribution of electrodes vertical positions is wider than their horizontal positions.DISCUSSION: These results can be translated directly to ECG wearable design for the individual and for the size range and adjustability required for the astronaut fleet. Implementation of this method will improve the reliability in placement and fit of future wearables, increasing comfort and usability of these systems and subsequently augmenting autonomous health monitoring capabilities for exploration medicine.Arquilla K, Leary S, Webb AK, Anderson AP. Wearable 3-lead electrocardiogram placement model for fleet sizing of medical devices. Aerosp Med Hum Perform. 2020; 91(11):868875.

Wireless battery-free wearable sweat sensor powered by human motion.

Wireless wearable sweat biosensors have gained huge traction due to their potential for noninvasive health monitoring. As high energy consumption is a crucial challenge in this field, efficient energy harvesting from human motion represents an attractive approach to sustainably power future wearables. Despite intensive research activities, most wearable energy harvesters suffer from complex fabrication procedures, poor robustness, and low power density, making them unsuitable for continuous biosensing. Here, we propose a highly robust, mass-producible, and battery-free wearable platform that efficiently extracts power from body motion through a flexible printed circuit board (FPCB)-based freestanding triboelectric nanogenerator (FTENG). The judiciously engineered FTENG displays a high power output of ~416 mW m-2 Through seamless system integration and efficient power management, we demonstrate a battery-free triboelectrically driven system that is able to power multiplexed sweat biosensors and wirelessly transmit data to the user interfaces through Bluetooth during on-body human trials.

General Conceptual Framework of Future Wearables in Healthcare: Unified, Unique, Ubiquitous, and Unobtrusive (U4) for Customized Quantified Output

We concentrate on the importance and future conceptual development of wearable devices as the major means of personalized healthcare. We discuss and address the role of wearables in the new era of healthcare in proactive medicine. This work addresses the behavioral, environmental, physiological, and psychological parameters as the most effective domains in personalized healthcare, and the wearables are categorized according to the range of measurements. The importance of multi-parameter, multi-domain monitoring and the respective interactions are further discussed and the generation of wearables based on the number of monitoring area(s) is consequently formulated.

Building Circular Economy for Smart Textiles, Smart Clothing, and Future Wearables

As the textile and garment industries aim at minimizing the impact caused by mass fabrication, fast consumption and relatively short utility span of materials and products, they focus on Circular Economy (CE) principles as a feasible solution. In order to build a new practice, lifestyle and ecology under the upcoming CE transition, in this manuscript we propose new approaches to implement concepts such as materials circularity index (CI) and clothing utility (CU), at personal and social levels and through new design and geometry guidelines. We believe these proposed strategies will be key in building a circular economy for smart textiles, smart clothing and future wearables.

A linear-to-rotary hybrid nanogenerator for high-performance wearable biomechanical energy harvesting

Harvesting biomechanical energy from low-frequency human body motions is a challenging but promising approach to powering the future wearables. Herein, we report a linear-to-rotary hybrid nanogenerator (LRH-NG) to effectively harvest low-frequency body biomechanical energy via a frequency enhancement strategy. Remarkably, the generated current and voltage by the LRH-NG from human body movement are respectively enhanced up to 3.1 times and 3.6 times of that at the basic frequency (2 Hz). Furthermore, the LRH-NG was demonstrated as an on-body electricity generator that can sustainably power a body area network with a temperature sensor and a humidity sensor for personalized health care. The designed LRH-NG may open up a new approach for high-performance low-frequency wearable biomechanical energy harvesting as a sustainable and pervasive energy solution in the era of the Internet of things.

The Emerging Role of Wearable Technologies in Detection of Arrhythmia

Over the past decade, there has been an explosion of consumer devices for the purposes of health and fitness tracking. The wearable technology market, composed of devices that monitor physiological parameters, such as heart rate and sleep pattern, is anticipated to grow to 929 million connected devices in 2021. These devices encompass wristbands, glasses, in-ear monitors, or electronic shirts, with varying capacity to monitor heart rate, heart rhythm, blood pressure, physical activity, respiratory rate, blood glucose, and sleep patterns. For heart-rate monitoring, most wearable devices use photoplethysmography (PPG) technology, meaning they are inherently less accurate than conventional electrocardiography monitoring techniques (reference standard). However, a growing body of evidence suggests that these technologies can be harnessed to facilitate arrhythmia detection in the appropriate context. Studies evaluating PPG-based wearables in conjunction with machine-learning algorithms have shown promise in detection of such arrhythmias, as atrial fibrillation. Limitations of wearable technologies include their accuracy and accessibility and the clinical implications of wearable-detected arrhythmias. Despite this, wearable technologies represent an important frontier in health evaluation. Future wearables will benefit from improved reliability and accuracy, collect additional health and fitness parameters, support management of chronic disease, and provide real-time connectivity and feedback that may supplant conventional medical monitoring. Wearables have the potential to become truly disruptive in our health care sector, with large segments of the population soon to have readily available health data that the physician must interpret.

Is an Activity Tracker in the Future for Childhood Obesity Management?

Welcome to the Pediatric Obesity Column for JPSN! This column’s mission is to provide information and resources to the pediatric surgical nurse caring for children affected by obesity. Our goal is to share emerging information and strategies based on physiology and biochemistry that can be incorporated into the practitioner’s daily practice. In the area of fitness, technology continues to be updated at a fast pace. Numerous monitors are available for purchase from the very affordable to the very expensive. They offer a way to track activity, food and water intake, and sleep. Some also offer games and encouragement. Some physicians have already tapped into this market to assist in personalized treatment of chronic diseases such as diabetes and HIV with increasing interest being shown toward this method of monitoring patients outside the medical office. Childhood obesity is now targeted by medical professionals and by companies who recognize the difficulty in obtaining an accurate picture of the daily life of the child and keeping children and families engaged in healthy habits. This short article will introduce readers to types of tracking devices available. Regular use of monitoring devices is the key to worthwhile patient information. Regular use is enhanced by technical friendliness (easy-to-download software), willingness to be tracked, and device appearance (Chiauzzi, Rodarte, & DasMahapatra, 2015). Kim (2014) predicts that future wearables will not only have the characteristics listed above but also automatically download information, ensuring an accurate picture of the patients’ day-to-day health pattern. Also crucial to the use of activity trackers is that patients feel comfortable that their information remains private no matter how it is relayed to the caregiver (Chiauzzi et al., 2015). A systematic review by Stephens and Allen (2013) of the use of smartphone applications and text messaging used to promote weight loss and activity noted that, in over half of the studies, statistically significant improvements were realized for weight loss, increased physical activity, healthier dietary intake, decreased body mass index, decreased waist circumference, decreased sugar-sweetened beverage intake, deceased screen time, and satisfaction or acceptability outcomes (Stephens & Allen, 2013). In addition, the data obtained by these means were not stand-alone. Each study was backed by educational components and/or interventions, which are the typical standard used presently by medical professionals (Stephens & Allen, 2013). The following link provides a current list of activity trackers and the list of criteria the trackers met to be included on this summary. This online site also gives a lesson on how to choose an activity tracker and a detailed review of each one. Here’s to happy tracking! http://fitness-trackers-review.toptenreviews.com/