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Long-term pulse monitoring plays a vital role in the prevention and diagnosis of cardiovascular diseases since pulse signals can provide rich characteristics of cardiac conditions. Flexible sensors mounting on the wrist for pulse monitoring have drawn great attention due to the advantages of soft, skin-interfaced and non-invasive features. However, slight wrist movement and transposition of the sensor on skin would dramatically impact the signal quality because of motion artifacts and interfacial properties. Here, we report an intelligent skin-integrated system by combining a sensitive pressure sensor array and a signal enhancement algorithm to provide reliable pulse signal monitoring. The sensors have the advantages of low cost, simple fabrication, reusability and high sensitivity. The multiple sensor channels offer rich information of vital signals, which can facilitate deep learning-based algorithms to denoise and reconstruct pulses more accurately and thus enable precise heart rate monitoring and heart variability assessments. The reported technology suggests a novel approach for pulse waveform detection in static and dynamic conditions, allowing users to more easily achieve reliable pulse monitoring. [Display omitted] • A flexible pressure sensor array offers non-invasive, and reliable arterial pulse wave monitoring without precise placement. • Deep learning techniques are used to enhance the sensing signal quality. • A general strategy to improve the accuracy of multiple cardiac health parameters in both static and dynamic conditions. [ABSTRACT FROM AUTHOR]

Organic electrochemical transistors (OECTs) with high transconductance, low driving voltage, and biocompatibility have emerged as dominant bioelectronics technologies. However, a significant challenge remains in achieving stable signal recording over extended durations, due to the restricted thermal and cycling stability. Here, by introducing a small molecular with double-end functionalized trifluoromethyl-substituted diazirine (DtFDA) as the crosslinker in the organic mixed ionic-electronic conductors (OMIECs), both p- and n-type vertical OECT (vOECT) achieves excellent thermal adaptability (> 100 °C), excepti°nal cycling stability (> 200,000 cycles), fast ion transporting capability (transient time < 1 ms), along with ultrahigh maximum transconductance (g m) (> 0.34 S). The findings reveal that highly loaded crosslinkers (OMIEC:DtFDA = 1:1 in mass) triggered by ultraviolet can facilitate the formation of stable and homogeneous transistor channel, which holds lower crystallinity, wider d spacing, and face-on dominated packing, thereby leading to enhanced ion hydration/injection and decent carrier transport pathways. Moreover, in vivo brain recordings with stable signals were accessed from the developed ultraflexible vOECT even after a four-week interval, and the tissue biocompatibility was also validated by chronic epicortical implantation. This work signifies new possibilities for high-performance vOECTs with high fidelity signals recording under complicated operation environments, enabling broader implications for robust bioelectronics. [Display omitted] • Ultrahigh electrical performance of vOECTs via high-loading crosslinking approach are achieved. • Excellent thermal adaptability (>100°C) and cycling stability (>200,000 cycles) of vOECT are demonstrated. • In vivo brain recordings with stable signals even after a four-week implantation interval are accessed. [ABSTRACT FROM AUTHOR]

Tunnel lighting consumes nearly 30 % of the energy in the whole infrastructure, so optimizing the lighting control strategy could significantly increase the energy utilization efficiency. However, there is still lack of an intelligent and cost-effective lighting control system. Here, we report a low-cost, intelligent, and self-powered tunnel lighting control system based on the mechanical-regulated and soft-contact hybridized nanogenerator (MS-HNG) as both the power supply and distributed traffic monitoring sensor. Benefited from the mechanical regulation and frequency up-conversion design, the MS-HNG can effectively convert the energy into electricity from intermittent stimulation of the moving vehicle and thus offers a maximum output power of 108 mW to transmit the traffic information wirelessly. The introducing of soft fur also endows HNG with excellent stability and durability, showing a negligible decrease in the output over 100,000 cycles. Moreover, an "illumination traveling with the vehicle" sustainable tunnel lighting system which could save energy by 72 % at a traffic volume of 20 veh/h compared with the traditional one is successfully demonstrated. This work may pave the way for industrial applications of nanogenerators and shows great potential in energy-efficient and intelligent transportation systems (ITS). [Display omitted] [ABSTRACT FROM AUTHOR]

DNA based chemical sensor for the detection of nitrogen dioxide (NO 2 ) enabled by organic field-effect transistor (OFET) was fabricated. In this OFET-based chemical sensor, DNA was introduced between the gate dielectric and the organic semiconducting layer via spray-coating to function as the detecting layer for NO 2 analyte. Comparing with the OFET without the DNA interlayer, an enhanced sensing performance of OFET with the DNA interlayer was observed when exposed to various concentrations of NO 2 analyte. The sensitivity of the OFET-based sensor with DNA interlayer was nearly one order of magnitude higher than that of the controlled device. The results showed that there were the remarkable shifts of saturation current and charge carrier mobility after exposed to NO 2 analyte. By analyzing the electrical characteristics, and the morphologies of the dielectrics and pentacene films of the OFET-based sensors, the performance enhancement was ascribed to the negatively charged phosphate groups in DNA molecules, which could interact with NO 2 analytes and lead to a superior sensing performance of OFET incorporating with DNA. [ABSTRACT FROM AUTHOR]

Flexible and wearable electronics have presented a wide range of advantages to non-invasive real-time human health monitoring. However, its remarkable energy consumption during continuous and long-time operation brings essential, practical challenges, which lead to growing recognition of exploring new and efficient energy strategies for wearables. Here, inspired by human joints as a biomechanical energy source that shows an ideal option for sustainable powers, we design a battery-free sweat sensing system integrated with sweat resistant self-sustainable energy supply and wireless communication interface, where piezoelectric nanogenerators (PENGs) efficiently converting biomechanical energy from freely movable joints (finger, cubital fossa and popliteal space) into electricity serving as the self-powering module. Physiological relevant parameters in sweat, including Na+ , K+ and pH, are sensed and wirelessly transmitted to the user interface via Bluetooth communication. This system shows a paradigm of wearable electronics driven by human joints that demonstrated efficient self-sustainable energy supply and multiplexed physiological detection. Inspired by human joints as a biomechanical energy source, we designed a battery-free sweat sensing system integrated with self-sustainable energy supply and wireless communication interface. PENG converts biomechanical energy from freely movable joints into electricity. Na+, K+ and pH in sweat are detected and wirelessly transmitted to the user interface via Bluetooth communication. [Display omitted] • PENG can efficiently convert joint movements into electricity. • Na+, K+ and pH of sweat can be detected by a flexible sensor patch. • Finger, arm and leg are preferred joint candidates for energy harvesting. • Biomechanical energy of human joints can power flexible electronic device. [ABSTRACT FROM AUTHOR]

In the past decades, wearable electronics have attracted extensive attention for their excellent electrical performance and superior mechanical characteristics in various applications, including human machine interfaces, clinical treatment, and healthcare monitoring. Powering technology as the indispensable component for intelligent wearable electronics, have raised much concern for bulky size, low energy capacity, and rigid format. Here, we have developed an ultrathin, flexible, conformable sweat activated battery with the high power density (16.3 mW/cm2) and impressive energy capacity (74.4 mAh). Due to the advanced biocompatible materials, the battery is capable of mounting onto human skin for long-term application without any irritation risk. After optimizing the electrical characteristics, the battery@ 0.3 mm Mg layer can yield the high open-circuit voltage and short-circuit current of 1.41 V and 53.4 mA for a long time (over 3.5 hrs). Besides, the battery can stabilize its electrical performance under various mechanical deformations, such as bending, twisting at different angles, which shall lead to the practical applications as mounted onto human body. The high-performance sweat-activated batteries@ 0.1 mm Mg layer enable powering electronic devices for a long-term duration, for instance, continuously lighting 120 LEDs for over 4 hrs, and also offer enough power to support Bluetooth wireless operation for recording of physiological signals for over 1.2 hrs, allowing real-time monitoring of exercising intensity level, skin temperature, pulse rate, and oxygen saturation in blood. An ultrathin, flexible, conformable sweat activated battery has been developed in this work with the high power density (16.3 mW/cm2) and energy capacity (74.4 mAh), that enables lighting 120 LEDs for 4 hrs, and also offers enough power to support Bluetooth wireless operation in wearable electronics for continuously monitoring physiological signals including activities, body temperature, pulse rate and oxygen saturation. [Display omitted] • The flexible sweat activated battery could yield a high capacity and power density of 74.4 mAh and 16.3 mW/cm2. • The battery has exhibited stable electrical performance under various mechanical deformations, including bending and twisting. • The flexible battery could support a Bluetooth module based microelectronics for human physiological signal monitoring. [ABSTRACT FROM AUTHOR]

Abstract: The performance of n-type organic field-effect transistors (OFETs) based on C60 active layer was investigated by focusing on the role of 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBi), bathocuproine (BCP) and bathophenanthroline (Bphen) as buffer layers. It was found that the OFETs with the organic buffer layers exhibited significant improved electrical characteristics, such as saturation current, threshold voltage, field-effect mobility and current on/off ratio. Moreover, by optimizing the film thicknesses of these buffer layers, we also found that the buffer layers with appropriate film thickness can effectively improve charge carrier injection from Ag source/drain electrodes to C60 films. Also, the interface properties and the contact resistance between Ag source/drain electrodes and C60 films have been analyzed. [Copyright &y& Elsevier]

Abstract: Ammonia (NH3) sensors based on bottom contact organic field-effect transistors (OFETs) were created using pentacene as an active layer and polymerthylmethacrylate (PMMA) as an insulator. The OFET sensors exhibited a change in the electric characteristic such as the threshold voltage, the saturation current, and the field-effect charge carrier mobility when the sensors were exposed to different NH3 concentrations. Meanwhile, the favorable and rapid NH3 response characteristics of the OFET sensors were observed from the change in the drain-source current as a function of time, when the sensors were exposed to various cycles of exposure/evacuation of different NH3 concentrations ranging from 10 to 100ppm. Moreover, the environmental stability of the OFET sensors to constantly detect the NH3 gas in air was studied by storing the sensors in air for 30days. [Copyright &y& Elsevier]

Recent advances in flexible electronics have brought great promotions to the next generation of wearable devices, like electronic skin (E-skin). Nevertheless, the powering issue still limits the size, weight and cost for E-skin. Here, trampoline inspired mechanics design and processing techniques in epidermal electronics are combined together to develop a thin, soft, stretchable self-powered tactile sensors based on triboelectric effect for E-skin. With the assistance of microstructure modifying by sandpapers, the TENG sensor exhibits great improved electrical performance and capable of distinguishing a broad range of pressure, with a great sensitivity of 0.367 mV Pa−1. The resulted TENG sensor exhibits excellent stretchability and sensing stability with accurate unchanged signal outputs even under a high-level strain up to 35%. Demonstrations of the sensors associating with the integration with a glove for human-machine interfaces and the development of a 4 × 4 tactile array for pressure mapping and recognition of contact objects, offers great opportunity for next generation self-powered E-skin. ga1 ● Trampoline inspired design in electrode of the TENG sensor for great stretchability. ● TENG-based tactile sensors exhibit great and stable electrical performance under high-level strain. ● E-skin format TENG sensor array for tactile mapping. [ABSTRACT FROM AUTHOR]

Mechanics designs in wearable skin-integrated electronics, also known as epidermal electronics, play an important role in the device performance ranging from flexibility, to robusticity, and to the overall electrical performance. Compared with conventional wearable electronics, self-powered electronics that converting mechanical energy to electricity by using the activities from body's daily motions offers advantages of simple device structures and battery-free characteristics. Here we study a class of mechanics designs that associate with effective working area for stretchable epidermal triboelectric nanogenerators (e-TENGs), and report the relationships between effective working area and the electrical performance of e-TENGs. With the advanced cobweb-serpentine pattern mechanics design, a simple structured, low-cost single-electrode mode e-TENG with open-circuit voltage of ~60 V and a short circuit current output of ~20 μA was achieved. Moreover, the e-TENG's performance is very stable under a broad range of strain values from 0% to 30%. The report of mechanics designs-performance relationships shows a trade-off behavior between the stretchability and the effective working area, which significantly enhances our understanding of mechanics designs for e-TENGs. Image 1 • First report the relationships between effective working area and the electrical performance of epidermal TENGs. • With cobweb-serpentine mechanics design, the relationship between electrical performance and stretchability is evaluated. • By trading-off between performance and stretchability, e-TENG with an optimized design can provide a superior output under up to ~30% strain. • Thin, soft and flexible enough for mounting on skin to harvest energy from daily motion. [ABSTRACT FROM AUTHOR]