All-nanofiber-based, ultrasensitive, gas-permeable mechanoacoustic sensors for continuous long-term heart monitoring.

The prolonged and continuous monitoring of mechanoacoustic heart signals is essential for the early diagnosis of cardiovascular diseases. These bodily acoustics have low intensity and low frequency, and measuring them continuously for long periods requires ultrasensitive, lightweight, gas-permeable mechanoacoustic sensors. Here, we present an all-nanofiber mechanoacoustic sensor, which exhibits a sensitivity as high as 10,050.6 mV Pa-1 in the low-frequency region (<500 Hz). The high sensitivity is achieved by the use of durable and ultrathin (2.5 µm) nanofiber electrode layers enabling a large vibration of the sensor during the application of sound waves. The sensor is ultralightweight, and the overall weight is as small as 5 mg or less. The devices are mechanically robust against bending, and show no degradation in performance even after 1,000-cycle bending. Finally, we demonstrate a continuous long-term (10 h) measurement of heart signals with a signal-to-noise ratio as high as 40.9 decibels (dB).

Printable elastic conductors by in situ formation of silver nanoparticles from silver flakes.

Printable elastic conductors promise large-area stretchable sensor/actuator networks for healthcare, wearables and robotics. Elastomers with metal nanoparticles are one of the best approaches to achieve high performance, but large-area utilization is limited by difficulties in their processability. Here we report a printable elastic conductor containing Ag nanoparticles that are formed in situ, solely by mixing micrometre-sized Ag flakes, fluorine rubbers, and surfactant. Our printable elastic composites exhibit conductivity higher than 4,000 S cm-1 (highest value: 6,168 S cm-1) at 0% strain, and 935 S cm-1 when stretched up to 400%. Ag nanoparticle formation is influenced by the surfactant, heating processes, and elastomer molecular weight, resulting in a drastic improvement of conductivity. Fully printed sensor networks for stretchable robots are demonstrated, sensing pressure and temperature accurately, even when stretched over 250%.

Effectiveness and safety of Liriope Tuber (Liriopis seu Ophiopogonis Tuber, Maidong) included traditional herbal medicine for patients with paroxysmal atrial fibrillation: A systematic review, meta-analysis, and network analysis.

Background: Conventional medicine (CM) for paroxysmal atrial fibrillation (PAF) have limitations and side effects. Integrative approaches, including traditional herbal medicines like Liriope Tuber, are being explored for potential benefits, although evidence remains limited. Methods: In April 2023, a literature search was conducted across nine databases, focusing on randomized controlled trials assessing the effects of Liriope Tuber in traditional herbal medicine (LTHM) on PAF. The risk of bias was evaluated using Version 2 of the Cochrane risk-of-bias tool for randomized trials. A random-effects model was employed for the meta-analysis. Results: A total of 43 studies with 3,743 participants were included. The meta-analysis indicated that adding LTHM to CM reduced PAF frequency (SMD = -0.99, 95 % CI = -1.40 to -0.57, I² = 88 %, N = 16, n = 1266), left atrium diameter (LAD) (MD = -2.39 mm, 95 % CI = -3.09 to -1.68), P-wave dispersion (Pd) (MD = -6.41 ms, 95 % CI = -8.44 to -4.37), high sensitive C-Reactive Protein (hs-CRP) (MD = -1.10 mg/l, 95 % CI = -1.73 to -0.47), and improved left ventricular ejection fraction (LVEF) (MD = 4.71 %, 95 % CI = 3.17 to 6.25). Thirty-four studies raised concerns about bias, with eight showing high risk. Certainty of evidence was rated as "low" for PAF frequency, LAD, Pd, hs-CRP, and LVEF. Conclusion: LTHM combined with CM may reduce PAF frequency. However, due to the complexity of interventions, with Liriope Tuber being only one component of the regimen, high risk of bias, substantial heterogeneity, and indirectness, interpretations should be cautious. Study registration: PROSPERO (ID: CRD42023477926).

Effectiveness and safety of acupuncture modalities for overweight and obesity treatment: a systematic review and network meta-analysis of RCTs.

Introduction: The effectiveness and safety of acupuncture in the treatment of obesity have not been assessed. This poses a challenge for clinicians who choose to use acupuncture in the treatment of obesity, as they are unable to prioritize this approach based on outcome variables. Methods: In May 2024, a literature search of five databases was conducted. Only randomized controlled trials evaluating body weight (BW), body mass index, waist circumference (WC), and adverse events in patients with a body mass index (BMI) of 25 or higher for various acupuncture modalities were included. The risk of bias was assessed using the Cochrane risk-of-bias tool for randomized trials, version 2. Pairwise meta-analysis (PMA) and Bayesian network meta-analysis (NMA) were performed using a random effects model for quantitative synthesis. Results: Fourteen studies (n = 868) were included. The included studies evaluated the following acupuncture modalities: electroacupuncture (EA) (N = 6), laser acupuncture (LA) (N = 2), auricular acupuncture (AA) (N = 5), and manual acupuncture (MA) (N = 3). The PMA found that adding EA to usual care (UC), compared to UC alone, reduced BW (MD = 2.46, 95% CI = 1.12 to 3.80, I 2 = 58%, REM, N = 3, n = 157). The NMA of BW showed the following effect sizes for UC alone versus each acupuncture modality combined with UC: LA (MD = 2.09, 95% CI = 0.04 to 3.86), EA (MD = 2.04, 95% CI = 0.88 to 3.50), AA (MD = 1.69, 95% CI = -0.11 to 3.58), and MA (MD = 1.02, 95% CI = -0.82 to 2.94). The probability of each modality being the optimal treatment was evaluated using the surface under the cumulative ranking curve. EA was the most efficacious for BW and BMI, while LA was the most efficacious for WC. Discussion: EA and LA can effectively complement clinical obesity management. The number of included studies was limited, and publication bias may have occurred, necessitating a cautious interpretation of the results. Furthermore, most studies lasted between six and 12 weeks. Future clinical studies of acupuncture for obesity should include longer follow-up periods. Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=387788, identifier CRD42023387788.

Firefighters' medical use and Korean Medicine experience in Korea: A qualitative study protocol.

INTRODUCTION: Firefighters, compared to other occupational groups, are exposed more frequently in their working environment not only to physical issues, such as musculoskeletal disease, respiratory disease, and burns but also to mental health issues, such as PTSD and depression. Specifically, Korean firefighters experience significantly higher rates of work-related injuries compared to those in other countries. Recent statistics from the Korea National Fire Agency indicate a steady increase in the number of firefighting work-related injuries. However, there is a shortage of measures in place to address these issues. This study aims to investigate the health needs, overall healthcare usage, and unmet needs of firefighters in Korea. We also aim to investigate, through in-depth interviews, perceptions and hindering factors for integrative medicine approaches to fulfilling unmet needs. METHOD: This study was conducted in accordance with the consolidated criteria for reporting qualitative research. Convenience and snowball sampling methods will be used to recruit firefighters to participate in the study, and interviews will be conducted using a semi-structured interview guide. The data will be analyzed in four stages using the qualitative analysis method of Krippendorff. DISCUSSION: In this study, we examine the state of health issues and healthcare usage among Korean firefighters and investigate their perceptions of and needs for integrative medicine. In this way, we aim to explore how integrative medicine and Korean medicine approaches could improve and assist healthcare services for firefighters. Furthermore, our findings will provide policymakers and healthcare providers with the necessary basic information to develop integrative medicine systems suited to firefighters.

Highly Durable Nanofiber-Reinforced Elastic Conductors for Skin-Tight Electronic Textiles.

Soft and stretchable electrodes are essential components for skin-tight wearable devices, which can provide comfortable, unobtrusive, and accurate physiological monitoring and physical sensing for applications such as healthcare, medical treatment, and human-machine interfaces. Metal-elastomer nanocomposites are a promising approach, enabling high conductivity and stretchability derived from metallic conduction and percolation networks of metal nano/micro fillers. However, their practical application is still limited by their inferior cyclic stability and long-term durability. Here, we report on a highly durable nanofiber-reinforced metal-elastomer composite consisting of (i) metal fillers, (ii) an elastomeric binder matrix, and (iii) electrospun polyvinylidene fluoride nanofibers for enhancing both cyclic stability and conductivity. Embedded polyvinylidene fluoride (PVDF) nanofibers enhance the toughness and suppress the crack growth by providing a fiber reinforcing effect. Furthermore, the conductivity of nanofiber-reinforced elastic conductor is four times greater than the pristine material because the silver-rich layer is self-assembled on the top surface by a filtering effect. As a result, a stretchable electrode made from nanofiber-reinforced elastic conductors and wrinkled structures has both excellent cyclic durability and high conductivity and is stretchable up to 800%. The cyclic degradation (ΔR/R0) remains at 0.56 after 5000 stretching cycles (50% strain), whereas initial conductivity and sheet resistance are 9903 S cm-1 and 0.047 Ω sq-1, respectively. By utilizing a highly conductive and durable elastic conductor as sensor electrodes and wirings, a skin-tight multimodal physiological sensing suit is demonstrated. Continuous long-term monitoring of electrocardiogram, electromyogram, and motions during weight-lifting exercises are successfully demonstrated without significant degradation of signal quality.

Highly Stretchable Metallic Nanowire Networks Reinforced by the Underlying Randomly Distributed Elastic Polymer Nanofibers via Interfacial Adhesion Improvement.

On-skin electronics require conductive, porous, and stretchable materials for a stable operation with minimal invasiveness to the human body. However, porous elastic conductors that simultaneously achieve high conductivity, good stretchability, and durability are rare owing to the lack of proper design for good adhesion between porous elastic polymer and conductive metallic networks. Here, a simple fabrication approach for porous nanomesh-type elastic conductors is shown by designing a layer-by-layer structure of nanofibers/nanowires (NFs/NWs) via interfacial hydrogen bonding. The as-prepared conductors, consisting of Ag NWs and polyurethane (PU) NFs, simultaneously achieve high conductivity (9190 S cm-1 ), high stretchability (310%), and good durability (82% resistance increase after 1000 cycles of deformation at 70% tensile strain). The direct contact between the Ag NWs enables the high conductivity. The synergistic effect of the layer-by-layer structure and good adhesion between the Ag NWs and the PU NFs enables good mechanical properties. Furthermore, without any adhesive gel/tape, the conductors can be utilized as breathable strain sensors for precise joint motion monitoring, and as breathable sensing electrodes for continuous electrophysiological signal recording.

Reverse-Offset Printed Ultrathin Ag Mesh for Robust Conformal Transparent Electrodes for High-Performance Organic Photovoltaics.

Mechanically durable transparent electrodes are needed in flexible optoelectronic devices to realize their long-term stable functioning, for applications in various fields such as energy, healthcare, and soft robotics. Several promising transparent electrodes based on nanomaterials have been previously reported to replace the conventional and fragile indium-tin oxide (ITO); however, obtaining feasible printed transparent electrodes for ultraflexible devices with a multistack structure is still a great challenge. Here, a printed ultrathin (uniform thickness of 100 nm) Ag mesh transparent electrode is demonstrated, simultaneously achieving high conductance, high transparency, and good mechanical properties. It shows a 17 Ω sq-1 sheet resistance (Rsh ) with 93.2% transmittance, which surpasses the performance of sputtered ITO electrodes and other ultrathin Ag mesh transparent electrodes. The conductance is stable after 500 cycles of 100% stretch/release deformation, with an insignificant increase (10.6%) in Rsh by adopting a buckling structure. Furthermore, organic photovoltaics (OPVs) using our Ag mesh transparent electrodes achieve a power conversion efficiency of 8.3%, which is comparable to the performance of ITO-based OPVs.

Ultraflexible Near-Infrared Organic Photodetectors for Conformal Photoplethysmogram Sensors.

Flexible organic optoelectronic devices simultaneously targeting mechanical conformability and fast responsivity in the near-infrared (IR) region are a prerequisite to expand the capabilities of practical optical science and engineering for on-skin optoelectronic applications. Here, an ultraflexible near-IR responsive skin-conformal photoplethysmogram sensor based on a bulk heterojunction photovoltaic active layer containing regioregular polyindacenodithiophene-pyridyl[2,1,3]thiadiazole-cyclopentadithiophene (PIPCP) is reported. The ultrathin (3 µm thick) photodetector exhibits unprecedented operational stability under severe mechanical deformation at a bending radius of less than 3 µm, even after more than 103 bending cycles. Deliberate optimization of the physical dimensions of the active layer used in the device enables precise on/off switching and high device yield simultaneously. The response frequency over 1 kHz under mechanically deformed conditions facilitates conformal electronic sensors at the machine/human interface. Finally, a mechanically stretchable, flexible, and skin-conformal photoplethysmogram (PPG) device with higher sensitivity than those of rigid devices is demonstrated, through conformal adherence to the flexuous surface of a fingerprint.

Enhancing the Performance of Stretchable Conductors for E-Textiles by Controlled Ink Permeation.

Delivery of electronic functionality to the human body using e-textiles is important for realizing the future of wearable electronics. Printing is a promising process for large scale manufacturing of e-textile since it enables arbitrary patterns using a simple and inexpensive process. However, conductive inks printed atop of textile are vulnerable to cracking because of the deformable and porous structure of textiles. The authors develop a mechanically and electrically robust wiring by controlling ink permeation in the structure of textile. This is done by adjusting the ink's solvent. The use of butyl carbitol acetate, with its low vapor pressure and boiling point, enables deep permeation into the textile. The sheet resistance is initially 0.06 Ω sq-1 , and the resistance increasing only 70 times after stretching to 450% strain. Finally, a four-channel electromyogram (EMG) monitoring garment is demonstrated to show the potential of a large-scale e-textile device for health care and sports.

Inflammation-free, gas-permeable, lightweight, stretchable on-skin electronics with nanomeshes.

Thin-film electronic devices can be integrated with skin for health monitoring and/or for interfacing with machines. Minimal invasiveness is highly desirable when applying wearable electronics directly onto human skin. However, manufacturing such on-skin electronics on planar substrates results in limited gas permeability. Therefore, it is necessary to systematically investigate their long-term physiological and psychological effects. As a demonstration of substrate-free electronics, here we show the successful fabrication of inflammation-free, highly gas-permeable, ultrathin, lightweight and stretchable sensors that can be directly laminated onto human skin for long periods of time, realized with a conductive nanomesh structure. A one-week skin patch test revealed that the risk of inflammation caused by on-skin sensors can be significantly suppressed by using the nanomesh sensors. Furthermore, a wireless system that can detect touch, temperature and pressure is successfully demonstrated using a nanomesh with excellent mechanical durability. In addition, electromyogram recordings were successfully taken with minimal discomfort to the user.

A transparent bending-insensitive pressure sensor.

Measuring small normal pressures is essential to accurately evaluate external stimuli in curvilinear and dynamic surfaces such as natural tissues. Usually, sensitive and spatially accurate pressure sensors are achieved through conformal contact with the surface; however, this also makes them sensitive to mechanical deformation (bending). Indeed, when a soft object is pressed by another soft object, the normal pressure cannot be measured independently from the mechanical stress. Here, we show a pressure sensor that measures only the normal pressure, even under extreme bending conditions. To reduce the bending sensitivity, we use composite nanofibres of carbon nanotubes and graphene. Our simulations show that these fibres change their relative alignment to accommodate bending deformation, thus reducing the strain in individual fibres. Pressure sensitivity is maintained down to a bending radius of 80 µm. To test the suitability of our sensor for soft robotics and medical applications, we fabricated an integrated sensor matrix that is only 2 µm thick. We show real-time (response time of ∼20 ms), large-area, normal pressure monitoring under different, complex bending conditions.