Wearable electronics with applications in healthcare, human-machine interfaces, and robotics often explore complex manufacturing procedures and are not disposable. Although the use of conductive pencil patterns on cel...
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Wearable electronics with applications in healthcare, human-machine interfaces, and robotics often explore complex manufacturing procedures and are not disposable. Although the use of conductive pencil patterns on cellulose paper provides inexpensive, disposable sensors, they have limited stretchability and are easily affected by variations in the ambient environment. This work presents the combination of pencil-on-paper with the hydrophobic fumed SiO2 (Hf-SiO2) coating and stretchable kirigami structures from laser cutting to prepare a superhydrophobic, stretchable pencil-on-paper multifunctional sensing platform. The resulting sensor exhibits a large response to NO2 gas at elevated temperature from self-heating, which is minimally affected by the variations in the ambient temperature and relative humidity, as well as mechanical deformations such as bending and stretching states. The integrated temperature sensor and electrodes with the sensing platform can accurately detect temperature and electrophysiological signals to alert for adverse thermal effects and cardiopulmonary diseases. The thermal therapy and electrical stimulation provided by the platform can also deliver effective means to battle against inflammation/infection and treat chronic wounds. The superhydrophobic pencil-onpaper multifunctional device platform provides a low-cost, disposable solution to disease diagnostic confirmation and early treatment for personal and population health.
Monitoring nitrogen utilization efficiency and soil temperature in agricultural systems for timely intervention is essential for crop health with reduced environmental pollution. Herein, this work presents a high-perf...
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Monitoring nitrogen utilization efficiency and soil temperature in agricultural systems for timely intervention is essential for crop health with reduced environmental pollution. Herein, this work presents a high-performance multi-parameter sensor based on vanadium oxide (VOX)-doped laser-induced graphene (LIG) foam to completely decouple nitrogen oxides (NOX) and temperature. The highly porous 3D VOX-doped LIG foam composite is readily obtained by laser scribing vanadium sulfide (V5S8)-doped block copolymer and phenolic resin self-assembled films. The heterojunction formed at the LIG/VOX interface provides the sensor with enhanced response to NOX and an ultralow limit of detection of 3 ppb (theoretical estimate of 451 ppt) at room temperature. The sensor also exhibits a wide detection range, fast response/recovery, good selectivity, and stability over 16 days. Meanwhile, the sensor can accurately detect temperature over a wide linear range of 10-110 degrees C. The encapsulation of the sensor with a soft membrane further allows for temperature sensing without being affected by NOX. The unencapsulated sensor operated at elevated temperature removes the influences of relative humidity and temperature variations for accurate NOX measurements. The capability to decouple nitrogen loss and soil temperature paves the way for the development of future multimodal decoupled electronics for precision agriculture and health monitoring.
Electronic skin has fast developed in recent years for its promising application in wearable sensing. Multifunction of breathability, self-adhesion, sweat release and diverse sensing is highly required but has not bee...
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Electronic skin has fast developed in recent years for its promising application in wearable sensing. Multifunction of breathability, self-adhesion, sweat release and diverse sensing is highly required but has not been achieved on a single device. Herein, inspired by natural human skin, we develop a breathable and self-adhesive electronic skin based on an all-nanofiber platform with unique directional moisture-wicking properties and bifunctional pressure and non-contact sensing capability. The multifunctional device is integrated with four functional parts self-adhesive gel, moisture-wicking structure, pressure sensing layer and non-contact detection layer. Benefits from structural design and advanced sensing principles, the sensor not only demonstrates high pressure-sensing sensitivity of 23 kPa-1 and ultrawide non-contact detection range of 2 m but also exhibits excellent breathability of 53.9 mm s-1 and fast moisture-wicking ability. Interestingly, the sensor can be tightly attached to human skin at skin temperature and be easily peeled off at elevated temperatures by using the temperature-controlled reversible phase-transition gel. Towards practical wearable sensing applications, different movements can be identified with 97.3 % accuracy by using the four-layer Multi-Layer Perceptron neural network. This work will boost the development of next-generation multifunctional electronic skins with both wearing comfortability and diverse sensing capability.
Effective protection from Pb2+ contamination calls for its rapid detection in environmental and biological samples, including water sources. This work demonstrates a rapid, highly sensitive and specific DNAzyme-based ...
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Effective protection from Pb2+ contamination calls for its rapid detection in environmental and biological samples, including water sources. This work demonstrates a rapid, highly sensitive and specific DNAzyme-based Pb2+ biosensor, which is also the first reported label free bioelectronic sensor for catalytic hydrolysis. The sensors are prepared from gold-plated interdigitated electrodes (IDEs), functionalized with oligonucleotide substrate strands and subsequent hybridization with DNAzyme strands. After sample fluid is applied onto a sensor for detection, the sensor's serial capacitance is continuously interrogated by an optimized alternating current (AC) signal for 15 s. If Pb2+ is present, the DNAzyme catalyzes a cleavage reaction of the substrate, releasing the DNAzyme and substrate fragments into the solution. The reaction leaves partial substrate strand at the sensor surface, causing a change in the IDEs' interfacial capacitance. Another novelty here is that capacitance measurement simultaneously induce a fluidic enrichment effect, AC electrothermal effect, thus concentrating and measuring Pb2+ in a single step. The AC signal is carefully optimized to minimize non-specific collection of macromolecules, including released DNAzyme and substrate fragments. In this work, Pb2+ level can be quantified in 15 s with a detection limit of 1.26 fM and a linear dynamic range from 1 fM to 1 pM in analytical buffer. To demonstrate the sensor's specificity, non-target metal ions are tested, all giving negligible responses. Testing of tap water samples collected under different conditions also yields reasonable results, validating the robustness of this sensor. This rapid and sensitive sensor holds high promise for on-site detection of Pb2+ in practical samples. (C) 2020 Elsevier Ltd. All rights reserved.
The growing demand for intelligent wearable electronic devices has spurred the rapid developments of high-performance deformable power supplies such as triboelectric nanogenerators (TENGs) with high output performance...
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The growing demand for intelligent wearable electronic devices has spurred the rapid developments of high-performance deformable power supplies such as triboelectric nanogenerators (TENGs) with high output performance. However, the intrinsically stretchable TENGs especially those prepared with low-cost manufacturing approaches still suffer from poor performance. To address the challenge, this paper presents a fully stretchable TENG consisting of an intrinsically stretchable MXene/silicone elastomer and silver nanowires (Ag NWs)graphene foam nanocomposite. The intrinsically stretchable TENG exhibits high output performance (voltage, current, and power of 73.6 V, 7.75 mu A, and 2.76 W m(-2)), long-term reliability, and stable electrical output under various extreme deformation conditions. In addition to the application on the human skin and clothing for human motion monitoring and detecting the strength training postures, the intrinsically stretchable TENG can also harvest the intermittent mechanical energy from human bodies to charge various energy storage units such as commercial capacitors for driving wearable electronic devices. The resulting systems have been demonstrated in applications from home anti-theft to water resources early warning systems, which provide the proof-of-the-concept demonstrations for the next-generation standalone device platforms.
Flexible temperature sensors show great potential in human health monitoring. However, sensitive materials and substrates of the reported temperature sensors have weak stretchability, mechanical compliance and breatha...
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Flexible temperature sensors show great potential in human health monitoring. However, sensitive materials and substrates of the reported temperature sensors have weak stretchability, mechanical compliance and breathability, which weakened the sensing stability and wearing comfort. Herein, a stretchable printed straininsensitive temperature sensor based on a multi-polygonal structure was developed. The highly printable temperature-sensitive ink preparation adopted a coagulation-assisted strategy by using polyvinyl alcohol (PVA) polymer as binder, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and graphene (G) as temperature-sensitive materials. By designing the multi-polygonal structure, the temperature sensor shows excellent anti-strain ability (even at 40 % strain) and good compliance with elastic human skin. Owing to the PEDOT:PSS with high temperature-sensitivity, G with 2D structure and excellent thermal conductivity, thermoplastic polyurethane (TPU) nanofiber with microporous structure, the fabricated sensor has high sensitivity and fast response speed. Benefiting from the microchannel and hydrophobic properties of the nanofiber substrate, the sensor has outstanding breathability and sweat resistance, laying the foundation for long-term wear comfort. Meanwhile, an electromechanical system and 4x4 temperature array have been built and applied to monitor human temperature and recognize the temperature distribution of objects successfully. This study provides a practical and optimized method for real-time and stable monitoring of human health.
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