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Flexible pressure sensors have attracted increasing research interest because of their potential applications for wearable sensing devices. Herein, a highly sensitive flexible pressure sensor is exhibited based on the elastomeric electrodes and a microarray architecture. Polydimethylsiloxane (PDMS) substrate, coated with silver nanowires (AgNWs), is used as the top electrode, while polyvinylidene fluoride (PVDF) as the dielectric layer. Several transfer processes are applied on seeking facile strategy for the preparation of the bottom electrode via embedding AgNWs into the PDMS film of microarray structure. The flexible pressure sensor integrates the top electrode, dielectric layer, and microarray electrode in a sandwich structure. It is demonstrated that such sensors possess the superiorities of high sensitivity (2.94 kPa), low detection limit (<3 Pa), short response time (<50 ms), excellent flexibility, and long-term cycle stability. This simple process for preparing such sensors can also be easily scaled up to construct pressure sensor arrays for detecting the intensity and distribution of the loaded pressure. In addition, this flexible pressure sensor exhibits good performance even in a noncontact way, such as detecting voice vibrations and air flow. Due to its superior performance, this designed flexible pressure sensor demonstrates promising potential in the application of electronic skins, as well as wearable healthcare monitors.

BACKGROUND Transcutaneous low-level tragus electrical stimulation (LLTS) suppresses atrial fibrillation (AF) in canines. OBJECTIVES We examined the antiarrhythmic and anti-inflammatory effects of LLTS in humans. METHODS Patients with paroxysmal AF who presented for AF ablation, were randomized to either 1 hour of LLTS (n = 20) or sham control (n = 20). Attaching a flat metal clip onto the tragus produced LLTS (20 Hz) in the right ear (50% lower than the voltage slowing the sinus rate). Under general anesthesia, AF was induced by burst atrial pacing at baseline and after 1 hour of LLTS or sham. Blood samples from the coronary sinus and the femoral vein were collected at those time points and then analyzed for inflammatory cytokines, including tumor necrosis factor (TNF)-α and C-reactive protein (CRP), using a multiplex immunoassay. RESULTS There were no differences in baseline characteristics between the 2 groups. Pacing-induced AF duration decreased significantly by 6.3 ± 1.9 min compared to baseline in the LLTS group, but not in the controls (p = 0.002 for comparison between groups). AF cycle length increased significantly from baseline by 28.8 ± 6.5 ms in the LLTS group, but not in controls (p = 0.0002 for comparison between groups). Systemic (femoral vein) but not coronary sinus TNF-α and CRP levels decreased significantly only in the LLTS group. CONCLUSIONS LLTS suppresses AF and decreases inflammatory cytokines in patients with paroxysmal AF. Our results support the emerging paradigm of neuromodulation to treat AF.

Flexible pressure sensors are one of the vital component units in the next generation of wearable electronics for monitoring human physiological signals. In order to improve the sensing properties of the sensors, we demonstrate flexible, tunably resistive pressure sensors based on elastic microstructured polydimethylsiloxane (PDMS) film via a simple, low-cost colloid self-assembly technology, which uses monodispersed polystyrene (PS) microspheres as monolayer and an ordered sacrificial template. The sensors exhibit high sensitivity of -15 kPa under low pressure (<100 Pa), with fast response time (<100 ms), high stability over 1000 cycles of pressure loading/unloading, low-pressure detection limit of 4 Pa, and wide working pressure regime (<5 kPa) by optimizing the size of PS microspheres. Moreover, the multipixel arrays of the pressure sensor are fabricated to illustrate the sensing ability of space pressure distribution. The developed flexible pressure sensors are successfully used to detect human neck pulse, show great promise for monitoring human body motions, and have potential applications in wearable devices.

Flexible and lightweight high-performance electromagnetic interference shielding materials with minimal thickness, excellent mechanical properties, and outstanding reliability are highly desired in the field of fifth-generation (5G) communication, yet remain extremely challenging to manufacture. Herein, we prepared an ultrathin densified carbon nanotube (CNT) film with superior mechanical properties and ultrahigh shielding effectiveness. Upon complete removal of impurities in pristine CNT film, charge separation in individual CNTs induced by polar molecules leads to strong CNT–CNT attraction and film densification, which significantly improve the electrical conductivity, shielding performance, and mechanical strength. The tensile strength is up to 822 ± 21 MPa, meanwhile the electrical conductivity is as high as 902,712 S/m, and the density is only 1.39 g cm–3. Notably, the shielding effectiveness is over 51 dB with a thickness of merely 1.85 μm in the broad frequency range of 4–18 GHz, and it reaches to ∼82 dB at 6.36 μm and ∼101 dB at 14.7 μm, respectively. Further, such CNT film exhibits excellent reliability after an extended period in strong acid/alkali, high temperature, and high humidity. It demonstrates the best overall performance among representative shielding materials by far, representing a critical breakthrough in the preparation of shielding film toward applications in wearable electronics and 5G communication.

A flexible pressure sensor with high sensitivity has been proposed which consists of a typical sandwich structure by integrating a PDMS substrate with a micro-arrayed PDMS dielectric layer.

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Novel structure design and shielding mechanism of various shielding materials are critically reviewed. Measurement methods of far-field and near-field shielding are presented. Challenges and future perspectives for shielding materials are discussed.