Applications In Wearable Devices Research Articles

Highly conductive graphene fiber textile for electromagnetic interference shielding

Textiles with excellent electromagnetic interference (EMI) shielding properties are highly desirable to prevent interference between electronic devices and ensure their stable service in this era of serious electromagnetic radiation. However, prevalent method to prepare EMI shielding textiles focused on decorating conductive nanomaterials onto insulative textile, limiting the performance of textiles. Here, we directly weave highly conductive graphene fiber (GF) tows to obtain a GF textile with high EMI shielding performance. The electrical conductivity of GFs is improved by the restored conjugate structure and optimized crystallinity through efficient thermal annealing. An X-band EMI shielding effectiveness (SE) for GF textile of more than 90 dB is achieved owing to the high electrical conductivity of 8.5 × 105 S m−1 of GF. Overlapping two layers of textile weaved by GF yields an SE of more than 120 dB. Moreover, the woven GF textiles exhibit excellent durability of bending and pressing. Combined with the outstanding EMI shielding performance, the GF textiles show great potential for applications in wearable devices, communication, defense, and the Internet of Things.

Development of Composite-film-based Flexible Energy Harvester using Lead-free BCTZ Piezoelectric Nanomaterials

Composite-based piezoelectric devices are extensively studied to develop sustainable power supply and selfpowered devices owing to their excellent mechanical durability and output performance. In this study, we design a leadfree piezoelectric nanocomposite utilizing (Ba<sub>0.85</sub>Ca<sub>0.15</sub>)(Ti<sub>0.9</sub>Zr<sub>0.1</sub>)O<sub>3</sub> (BCTZ) nanomaterials for realizing highly flexible energy harvesters. To improve the output performance of the devices, we incorporate porous BCTZ nanowires (NWs) into the nanoparticle (NP)-based piezoelectric nanocomposite. BCTZ NPs and NWs are synthesized through the solidstate reaction and sol-gel-based electrospinning, respectively; subsequently, they are dispersed inside a polyimide matrix. The output performance of the energy harvesters is measured using an optimized measurement system during repetitive mechanical deformation by varying the composition of the NPs and NWs. A nanocomposite-based energy harvester with 4:1 weight ratio generates the maximum open-circuit voltage and short-circuit current of 0.83 V and 0.28 A, respectively. In this study, self-powered devices are constructed with enhanced output performance by using piezoelectric energy harvesting for application in flexible and wearable devices.

Research on the Application of Wearable Devices in University Physical Education Classes

Basketball, currently one of the most widely practiced sports in higher education institutions, has a dedicated club course specifically designed for basketball instruction, which has always been a popular elective class among students. Traditional public physical education courses with a focus on basketball instruction, despite having a strong mass foundation, encounter numerous challenges in actual teaching, such as high student-to-teacher ratios, insufficient facilities, and the inability to effectively track teaching outcomes. In this innovative reform of the basketball club course, wearable devices and AI technology are employed to effectively address the challenges of public physical education courses. Through subsequent data tracking, it has been observed that this approach significantly enhances classroom organizational efficiency and, consequently, elevates the overall teaching quality.

Vision-driven metasurfaces for perception enhancement

Metasurfaces have exhibited unprecedented degree of freedom in manipulating electromagnetic (EM) waves and thus provide fantastic front-end interfaces for smart systems. Here we show a framework for perception enhancement based on vision-driven metasurface. Human’s eye movements are matched with microwave radiations to extend the humans’ perception spectrum. By this means, our eyes can “sense” visual information and invisible microwave information. Several experimental demonstrations are given for specific implementations, including a physiological-signal-monitoring system, an “X-ray-glasses” system, a “glimpse-and-forget” tracking system and a speech reception system for deaf people. Both the simulation and experiment results verify evident advantages in perception enhancement effects and improving information acquisition efficiency. This framework can be readily integrated into healthcare systems to monitor physiological signals and to offer assistance for people with disabilities. This work provides an alternative framework for perception enhancement and may find wide applications in healthcare, wearable devices, search-and-rescue and others.

AI-Enabled Soft Sensing Array for Simultaneous Detection of Muscle Deformation and Mechanomyography for Metaverse Somatosensory Interaction.

Motion recognition (MR)-based somatosensory interaction technology, which interprets user movements as input instructions, presents a natural approach for promoting human-computer interaction, a critical element for advancing metaverse applications. Herein, this work introduces a non-intrusive muscle-sensing wearable device, that in conjunction with machine learning, enables motion-control-based somatosensory interaction with metaverse avatars. To facilitate MR, the proposed device simultaneously detects muscle mechanical activities, including dynamic muscle shape changes and vibrational mechanomyogram signals, utilizing a flexible 16-channel pressure sensor array (weighing ≈0.38g). Leveraging the rich information from multiple channels, a recognition accuracy of ≈96.06% is achieved by classifying ten lower-limb motions executed by ten human subjects. In addition, this work demonstrates the practical application of muscle-sensing-based somatosensory interaction, using the proposed wearable device, for enabling the real-time control of avatars in a virtual space. This study provides an alternative approach to traditional rigid inertial measurement units and electromyography-based methods for achieving accurate human motion capture, which can further broaden the applications of motion-interactive wearable devices for the coming metaverse age.

Freeze polymerization to modulate transverse-longitudinal polypyrrole growth on robust cellulose composite fibers for multi-scenario signal monitoring

Novel in-situ freeze polymerization assisted layer-by-layer self-assembly method was utilized to prepare robust regenerated cellulose fiber-polypyrrole (RCF-PPy) composite fibers with high-conductivity, where transverse-longitudinal polypyrrole growth on RCF was regulated by using Lewis acid FeCl3 in crystalline ice state with the template etching and oxidation effects. The RCF-PPy3 exhibited high strength (1.01 cN/dtex) and exceptional durability, withstanding mechanical deformation, friction (100 cycles), and ultrasonic washing (50 times), addressing the issues of poor interface adhesion and conductivity stability of conductive fibers. Furthermore, the composite fiber demonstrated high electrical conductivity of 87.66 mS cm−1 and outstanding sensing performances for monitoring strain, pressure, temperature (0.34 %/°C), and humidity (0.895 %/RH). Based on RCF-PPy3, a pressure sensor was constructed as a human–machine interface electronic device, achieving sedentary reminders, fingertip information transmission, indicating great potential applications in intelligent wearable fiber electronic devices.

Flexible carbon-coated FeNi alloy/PDMS nanocomposites toward a multifunctional high-performance electromagnetic absorber

The increasing prevalence of electromagnetic wave technology has raised concerns regarding electromagnetic pollution and its potential hazards. Microwave absorbing materials (MAMs) have emerged as an effective solution for capturing and dissipating electromagnetic waves. This study presents a novel approach for developing flexible microwave absorbers by dispersing carbon-coated FeNi alloy nanoparticles (FeNi@C NPs) into a polydimethylsiloxane (PDMS) matrix. The unique contributions lie in the mass production of (FeNi)@C NPs through the arc plasma and controlled making of (FeNi)@C/PDMS nanocomposites for practical electromagnetic wave (EMW) absorption/shielding application. Simultaneously, the formation mechanism of (FeNi)@C NPs is illustrated in detail by real-time optical emission spectroscopy. The obtained (FeNi)@C/PDMS nanocomposites show multifunctionality such as hydrophobicity and mechanical performance, rendering them suitable for applications in lightweight flexible electronics, wearable devices, and stealth technology. Through adjustments in the contents of (FeNi)@C fillers, the (FeNi)@C/PDMS nanocomposites exhibit excellent microwave absorption capacity. At a mass ratio of 15% of (FeNi)@C NPs, the minimum reflection loss is −33.51 dB at a thickness of 2.3 mm with an effective absorption band of 4.96 GHz. This enhanced performance is attributed to the synergistic effects of magnetic and dielectric loss, multiple reflection/scattering, conduction loss, and suitable impedance matching. Furthermore, the (FeNi)@C/PDMS nanocomposites demonstrate remarkable corrosion resistance, exhibiting a positive shift in corrosion potential to −0.18 V compared to bare aluminum (−0.83 V), along with a corresponding protection efficiency of 98.78%. In conclusion, this study provides a validated strategy for the fabrication of EMW absorption nanocomposites consisting of magnetic nanoparticle fillers and polymer matrix, highlighting their potential for application in intricate environments.

Impressions and Perceptions of a Smartphone and Smartwatch Self-Management Tool for Patients With COPD: A Qualitative Study

Background Patients with chronic obstructive pulmonary disease (COPD) often do not seek care until they experience an exacerbation. Improving self-management for these patients may increase health-related quality of life and reduce hospitalizations. Patients are willing to use wearable technology for real-time data reporting and perceive mobile technology as potentially helpful in COPD management, but there are many barriers to the uptake of these technologies. Objective We aimed to understand patients’ experiences using a wearable and mobile app and identify areas for improvement. Methods We conducted semi-structured interviews as part of a larger prospective cohort study wherein patients used a wearable and app for 6 months. We asked which features patients found accessible, acceptable and useful. Results We completed 26 interviews. We summarized our research findings into four main themes: (1) information, support and reassurance, (2) barriers to adoption, (3) impact on communication with health care providers, and (4) opportunities for improvement. Most patients found the feedback received through the app to be reassuring and useful. Some patients experienced technical difficulties with the app and found the wearable to be uncomfortable. Conclusions Patients found a wearable device and mobile application to be acceptable and useful for the management of COPD. We identified barriers to adoption and opportunities for improvement to the design of our app. Further research is needed to understand what people with COPD and their healthcare providers want and will use in a mobile app and wearable for COPD management.

Fabrication of an Optically Transparent Planar Inverted-F Antenna Using PEDOT-Based Silver Nanowire Clear Ink with Aerosol-Jet Printing Method towards Effective Antennas

We report the design, fabrication, and experimental characterization of an optically transparent printed planar inverted-F antenna (PIFA) operating at 2.45 GHz using the aerosol jet (AJ) printing method. The proposed antenna was fabricated using a clear conductive ink on glass and Delrin. The antenna exhibits a wide fractional bandwidth (FBW) of 20% centered at 2.45 GHz, with a peak realized gain of −3.6 dBi and transparency of ~80%. The proposed fabrication method provides a cost-effective and scalable solution for manufacturing transparent antennas with potential applications in wireless communication, sensing, and wearable devices operating at mmWave frequencies higher than 30 GHz.

Tri-network, physical cross-linked sodium alginate hydrogel with strongly self-healing capacity and highly tough, for wearable flexible devices

Physical cross-linked hydrogels offer advantageous self-healing and easy preparation for broad application in wearable flexible devices. However, compared to chemical crosslinking, physical crosslinking is relatively fragile, yielding weak mechanical properties that hinder further development. To solve this problem, we polymerized [2-(methacryloyloxy)ethyl]dimethyl-(propyl3-sulfonate) ammonium hydroxide (DMAPS) into SA-PMAA hydrogels to form a three-network physical cross-linked hydrogel with high strength and superior self-healing ability. PDMAPS possesses dipolar-dipole action between lateral base units and self-associating ability. By introducing PDMAPS into the SA-PMAA double network structure, we created a hydrogel with excellent self-healing properties and mechanical strength. The hydrogel boasts a mechanical strength of 41 KPa, a maximum elongation at break of 820 %, and 94.7 % self-healing efficiency after 12 h, surpassing most hydrogels. With its polar groups, the hydrogel offers great compatibility with most aqueous slurries containing inorganic fillers, making it a material with immense potential as a polyelectrolyte and broad applications in the field of biosensing and wearable flexible devices.

Application of Traditional Method and Smart Wearable Devices in Monitoring Physical Fitness: A Comparative Study

Application of Traditional Method and Smart Wearable Devices in Monitoring Physical Fitness: A Comparative Study

Multiple Redox‐Active Cyano‐Substituted Organic Compound Integrated with MXene Nanosheets for High‐Performance Flexible Aqueous Zn‐Ion Battery

AbstractAn eco‐friendly organic compound, with rich redox sites, considered a promising cathode material for aqueous zinc‐ion batteries (AZIBs). Despite its potential, limited specific capacity and cycle instability impede its practical application. Herein, an organic compound, hexaazatriphenylene hexacarbonitrile (6CN‐HAT), is designed with a π–π conjugated aromatic structure, and integrated with MXene nanosheets to construct a flexible self‐supporting electrode (6CN‐HAT@MXene). Ex‐situ characterizations and theoretical calculations verify that the charge storage mechanism predominantly involves coordination and non‐coordination reactions between reactive C═N and ─CN sites with cations. The introduction of MXene nanosheets not only bolster the stability and electronic conductivity of the 6CN‐HAT@MXene but also expose additional active sites for cation coordination. As a cathode material in AZIBs, 6CN‐HAT@MXene exhibits an outstanding discharge specific capacity of 413 mAh g−1 at 0.05 A g−1. Remarkably, even after 5000 cycles at 5 A g−1, the discharge capacity retained 91%. Furthermore, based on the 6CN‐HAT@MXene electrode, a flexible micro‐zinc‐ion batteries with high area capacity of 257.4 mF cm−2 is prepared using laser cutting technology, highlighting its potential for future applications in portable and wearable electronic devices.

Analysis of Minimal Channel Electroencephalography for Wearable Brain–Computer Interface

Electroencephalography (EEG)-based brain—computer interface (BCI) is a non-invasive technology with potential in various healthcare applications, including stroke rehabilitation and neuro-feedback training. These applications typically require multi-channel EEG. However, setting up a multi-channel EEG headset is time-consuming, potentially resulting in patient reluctance to use the system despite its potential benefits. Therefore, we investigated the appropriate number of electrodes required for a successful BCI application in wearable devices using various numbers of EEG channels. EEG multi-frequency features were extracted using the “filter bank” feature extraction technique. A support vector machine (SVM) was used to classify a left/right-hand opening/closing motor imagery (MI) task. Nine electrodes around the center of the scalp (F3, Fz, F4, C3, Cz, C4, P3, Pz, and P4) provided high classification accuracy with a moderate setup time; hence, this system was selected as the minimal number of required channels. Spherical spline interpolation (SSI) was also applied to investigate the feasibility of generating EEG signals from limited channels on an EEG headset. We found classification accuracies of interpolated groups only, and combined interpolated and collected groups were significantly lower than the measured groups. The results indicate that SSI may not provide additional EEG data to improve classification accuracy of the collected minimal channels. The conclusion is that other techniques could be explored or a sufficient number of EEG channels must be collected without relying on generated data. Our proposed method, which uses a filter bank feature, session-dependent training, and the exploration of many groups of EEG channels, offers the possibility of developing a successful BCI application using minimal channels on an EEG device.

Application of wearable light imaging device based on particle search algorithm in sports competition motion simulation

Application of wearable light imaging device based on particle search algorithm in sports competition motion simulation

A 2.3 V quasi-solid-state flexible supercapacitor of AC|PVA-Na2SO4//PVA-KOH|Zn@CFP with high specific energy

Activated carbon//zinc (AC//Zn) supercapacitors using alkaline electrolyte become promising as an energy storage device due to their impressive specific capacitance. However, it is limited by a narrow voltage window. In this work, a new type supercapacitor (AC|PVA-Na2SO4//PVA-KOH|Zn@CFP) was developed using a decoupled electrolyte system comprising Na2SO4-polyvinyl alcohol (PVA)//cation exchange membrane//KOH-PVA, AC as positive electrode and Zinc electrodeposited on the carbon fiber paper (Zn@CFP) as a negative electrode. Importantly, the operational cell voltage was successfully raised to 2.3 V. This design enables autonomous lighting a green light-emitting diode (LED) by a single device. The device delivers a specific capacity of 517.6C g−1 at 1 A g−1, corresponding to a specific energy of 186.9 Wh kg−1 at 1300 W kg−1, considering that the three-dimensional (3D) architecture of Zn@CFP offers a significantly enlarged surface area, thereby facilitating enhanced performance. The device also exhibited good stability, with a capacity retention of approximately 95.3 % after 1000 charge/discharge cycles. Furthermore, the PVA-based decoupled gel electrolyte offers excellent processability and remarkable flexibility. Remarkably, at an elevated temperature of 50 °C, the device showed an even higher specific energy of 238.8 Wh kg−1 at 1300 W kg−1. These findings underscore the substantial potential of the wide-voltage zinc-ion supercapacitor. Our strategy offers the device not only a high specific energy but also exceptional flexibility, rendering it highly promising for future applications in wearable electronic devices.

Flat-Silk-Cocoon-Based Wearable Flexible Piezoresistive Sensor and Its Performance.

Flexible sensors are becoming the focus of research because they are very vital for intelligent products, real-time data monitoring, and recording. The flat silk cocoon (FSC), as a special form of cocoon, has all the advantages of silk, which is an excellent biomass carbon-based material and a good choice for preparing flexible sensors. In this work, a flexible piezoresistive sensor was successfully prepared by encapsulating carbonized flat silk cocoons (CFSCs) using an elastic matrix polydimethylsiloxane (PDMS). The sensing performance of the material is 0.01 kPa-1, and the monitoring range can reach 680.57 kPa. It is proved that the sensor can detect human motion and has excellent durability (>800 cycles). In addition, a sensor array for a keyboard based on CFSCs was explored. The sensor has a low production cost and a simple preparation process, and it is sustainable and environmentally friendly. Thus, it may have potential applications in wearable devices and human-computer interactions.

Recent advances in intrinsically stretchable electronic materials and devices

AbstractIntrinsically stretchable electronics have gained extensive interest recently, due to their promising application in wearable electronics, bio‐integrated electronics, and healthcare devices. All of the components of such stretchable electronics need to be stretchable and mechanically robust to accommodate complex movements. The design and fabrication of robust intrinsically stretchable electronic materials represent a critical challenge in this emerging field. In this review, we focus on the latest studies of intrinsically stretchable electronics, covering the strategies for achieving intrinsically stretchable electronic materials, the recent progresses in the key electronic materials including intrinsically stretchable conductors, semiconductors, dielectrics, and the devices produced by them. Finally, some suggestions and prospects for the future development of intrinsically stretchable electronics are proposed.

High-Performance Piezoelectric Nanogenerator of BTO-PVDF Nanofibers for Wearable Sensing.

Piezoelectric nanogenerator (PENG) produces stable electrical signals in response to external mechanical stimuli and holds promise in the fields of flexible sensors and smart wearable devices. In practice, a high-performance PENG with a straightforward structure and exceptional reliability is deeply desired. This study optimally synthesizes piezoelectric composites comprising polyvinylidene fluoride (PVDF) incorporated with barium titanate (BTO) nanoparticles (NPs) and fabricated a PENG with heightened sensitivity by using the electrospinning technique. The polar β-phase content of the dual-optimized BTO-PVDF (barium titanate and polyvinylidene fluoride) electrospun fiber reaches up to 82.39%. In the bending mode, it achieves a remarkable maximum open-circuit voltage of 19.152V, a transferred charge of 8.058 nC, and an output voltage per unit area of 2.128Vcm- 2. Under vertical pressure conditions, the BP-PENG exhibits an impressive voltage of 12.361V while the force is 2.156 N, demonstrating a notable pressure sensing sensitivity of 5.159VkPa-1, with an excellent linear relationship. Furthermore, the BP-PENG displays sensitive sensing features in monitoring hand movements. The sensitive response and high performance make it promising for applications in human motion monitoring and smart wearable devices.

Solution spun electrically conductive nylon 6/poly(pyrrole) nanotubes-based composite fibers

Wearable electronic device applications require flexible polymer-based conducting fibers. Towards this, various conductive fillers have been used in a polymer matrix. However, it usually requires the addition of a high amount of fillers. In this study, electrically conductive composite fibers of nylon 6 (Ny)-poly(pyrrole) nanotubes (PPyNTs) have been demonstrated using the solution-spinning process. The high aspect ratio of PPyNTs can provide a good electrically conductive network and show a percolation threshold at a low concentration of PPyNTs in a nylon matrix. The composite fibers exhibited good DC electrical conductivity of ∼0.002 S/cm at only 6 wt% of PPyNTs. The influence of PPyNTs concentration on the morphology, physical, chemical, and electrical properties of the fibers have been investigated.

Highly stretchable and room-temperature self-healing sheath-core structured composite fibers for ultrasensitive strain sensing and visual thermal management

Highly stretchable and self-healing wearable electronics for strain sensing and Joule heating are highly desirable for future emerging applications of wearable devices, smart robots, human-machine interface and artificial intelligence, etc. Herein, the highly stretchable and room-temperature self-healing sheath-core structured composite fibers are fabricated via the feasible in-situ polymerization modification followed by electroless silver-plating approach. Benefitting from the simultaneous incorporation of dual dynamic reversible chemical networks and construction of sheath-core structures, the composite fibers show ultrasensitive strain sensing and visual thermal management performances with excellent room-temperature self-healing capacity at ultralow Ag loadings. The composite fibers after cutting and self-healing also exhibit outstanding strain sensing performances with a high gauge factor (GF) of 64.0 and visual thermal management performances with tailorable Joule heating temperatures. Furthermore, they possess excellent working stability and reliability in practical applications of human motion detection and personal thermal management. This work demonstrates the fabrication of highly stretchable and room-temperature self-healing composite fibers for next-generation wearable devices, smart robots, human-machine interface and artificial intelligence, etc.