Wireless Flexible System for Highly Sensitive Ammonia Detection Based on Polyaniline/Carbon Nanotubes.

Ammonia (NH3) is a harmful atmospheric pollutant and an important indicator of environment, health, and food safety conditions. Wearable devices with flexible gas sensors offer convenient real-time NH3 monitoring capabilities. A flexible ammonia gas sensing system to support the internet of things (IoT) is proposed. The flexible gas sensor in this system utilizes polyaniline (PANI) with multiwall carbon nanotubes (MWCNTs) decoration as a sensitive material, coated on a silver interdigital electrode on a polyethylene terephthalate (PET) substrate. Gas sensors are combined with other electronic components to form a flexible electronic system. The IoT functionality of the system comes from a microcontroller with Wi-Fi capability. The flexible gas sensor demonstrates commendable sensitivity, selectivity, humidity resistance, and long lifespan. The experimental data procured from the sensor reveal a remarkably low detection threshold of 0.3 ppm, aligning well with the required specifications for monitoring ammonia concentrations in exhaled breath gas, which typically range from 0.425 to 1.8 ppm. Furthermore, the sensor demonstrates a negligible reaction to the presence of interfering gases, such as ethanol, acetone, and methanol, thereby ensuring high selectivity for ammonia detection. In addition to these attributes, the sensor maintains consistent stability across a range of environmental conditions, including varying humidity levels, repeated bending cycles, and diverse angles of orientation. A portable, stable, and effective flexible IoT system solution for real-time ammonia sensing is demonstrated by collecting data at the edge end, processing the data in the cloud, and displaying the data at the user end.

Printable and flexible integrated sensing systems for wireless healthcare.

The rapid development of wearable sensing devices and artificial intelligence has enabled portable and wireless tracking of human health, fulfilling the promise of digitalized healthcare applications. To achieve versatile design and integration of multi-functional modules including sensors and data transmission units onto various flexible platforms, printable technologies emerged as some of the most promising strategies. This review first introduces the commonly utilized printing technologies, followed by discussion of the printable ink formulations and flexible substrates to ensure reliable device fabrication and system integration. The advances of printable sensors for body status monitoring are then discussed. Moreover, the integration of wireless data transmission via printable approaches is also presented. Finally, the challenges in achieving printable sensing devices and wireless integrated systems with competitive performances are considered, so as to realize their practical applications for personalized healthcare.

Efficient direct repairing of lithium- and manganese-rich cathodes by concentrated solar radiation.

Lithium- and manganese-rich layered oxide cathode materials have attracted extensive interest because of their high energy density. However, the rapid capacity fading and serve voltage decay over cycling make the waste management and recycling of key components indispensable. Herein, we report a facile concentrated solar radiation strategy for the direct recycling of Lithium- and manganese-rich cathodes, which enables the recovery of capacity and effectively improves its electrochemical stability. The phase change from layered to spinel on the particle surface and metastable state structure of cycled material provides the precondition for photocatalytic reaction and thermal reconstruction during concentrated solar radiation processing. The inducement of partial inverse spinel phase is identified after concentrated solar radiation treatment, which strongly enhances the redox activity of transition metal cations and oxygen anion, and reversibility of lattice structure. This study sheds new light on the reparation of spent cathode materials and designing high-performance compositions to mitigate structural degradation.

Ultra-Sensitive and Stable Multiplexed Biosensors Array in Fully Printed and Integrated Platforms for Reliable Perspiration Analysis.

Electrochemical biosensors have emerged as one of the promising tools for tracking human body physiological dynamics via non-invasive perspiration analysis. However, it remains a key challenge to integrate multiplexed sensors in a highly controllable and reproducible manner to achieve long-term reliable biosensing, especially on flexible platforms. Herein, a fully inkjet printed and integrated multiplexed biosensing patch with remarkably high stability and sensitivity is reported for the first time. These desirable characteristics are enabled by the unique interpenetrating interface design and precise control over active materials mass loading, owing to the optimized ink formulations and droplet-assisted printing processes. The sensors deliver sensitivities of 313.28 µA mm-1 cm-2 for glucose and 0.87 µA mm-1 cm-2 for alcohol sensing with minimal drift over 30 h, which are among the best in the literature. The integrated patch can be used for reliable and wireless diet monitoring or medical intervention via epidermal analysis and would inspire the advances of wearable devices for intelligent healthcare applications.

Well-defined in-textile photolithography towards permeable textile electronics.

Textile-based wearable electronics have attracted intensive research interest due to their excellent flexibility and breathability inherent in the unique three-dimensional porous structures. However, one of the challenges lies in achieving highly conductive patterns with high precision and robustness without sacrificing the wearing comfort. Herein, we developed a universal and robust in-textile photolithography strategy for precise and uniform metal patterning on porous textile architectures. The as-fabricated metal patterns realized a high precision of sub-100 µm with desirable mechanical stability, washability, and permeability. Moreover, such controllable coating permeated inside the textile scaffold contributes to the significant performance enhancement of miniaturized devices and electronics integration through both sides of the textiles. As a proof-of-concept, a fully integrated in-textiles system for multiplexed sweat sensing was demonstrated. The proposed method opens up new possibilities for constructing multifunctional textile-based flexible electronics with reliable performance and wearing comfort.

Blood miR-21 and miR-26 tailor a good diagnostic model for childhood asthma.

This study was to investigate the relationships between blood miR-21/26a with the prevalence and severity of childhood asthma (CAMP). For this purpose, 123 children with allergic asthma (AZ) from June 2018 to June 2020, and 60 contemporaneous healthy children for reference, were enrolled. Lung function was detected using a portable pediatric spirometer and AZ severity was evaluated. Blood samples of admissions were collected to quantify the expression degrees of miR-21 and miR-26a. Logistic regression analysis and model were constructed. Results showed that (1) CAMP had higher MiR-21 expression and lower MiR-26a expression than healthy controls; (2) The severity of AZ, evidenced by FEV1/PV, significantly correlated with miR-21(Y=-3.825X+102.6, P<0.001) and miR-26a (Y=10.43X+54.29, P<0.001); (3) The prevalence of AZ-related to miR-21 (OR=4.180, P<0.001) and miR-26a (OR=0.058, P<0.001) after adjusting for cofounders. (4) the expression levels of miR-21/26a had a good diagnostic potential for AZ (AUC are 0.85 and 0.94, respectively). In conclusion, Blood miRNA-21 and miR-26a are promising biomarkers for the diagnosis and severity of CAMP.

A monolithically integrated in-textile wristband for wireless epidermal biosensing.

Textile bioelectronics that allow comfortable epidermal contact hold great promise in noninvasive biosensing. However, their applications are limited mainly because of the large intrinsic electrical resistance and low compatibility for electronics integration. We report an integrated wristband that consists of multifunctional modules in a single piece of textile to realize wireless epidermal biosensing. The in-textile metallic patterning and reliable interconnect encapsulation contribute to the excellent electrical conductivity, mechanical robustness, and waterproofness that are competitive with conventional flexible devices. Moreover, the well-maintained porous textile architectures deliver air permeability of 79 mm s-1 and moisture permeability of 270 g m-2 day-1, which are more than one order of magnitude higher than medical tapes, thus ensuring superior wearing comfort. The integrated in-textile wristband performed continuous sweat potassium monitoring in the range of 0.3 to 40 mM with long-term stability, demonstrating its great potential for wearable fitness monitoring and point-of-care testing.

Fully Integrated Patch Based on Lamellar Porous Film Assisted GaN Optopairs for Wireless Intelligent Respiratory Monitoring.

Respiratory pattern is one of the most crucial indicators for accessing human health, but there has been limited success in implementing fast-responsive, affordable, and miniaturized platforms with the capability for smart recognition. Herein, a fully integrated and flexible patch for wireless intelligent respiratory monitoring based on a lamellar porous film functionalized GaN optoelectronic chip with a desirable response to relative humidity (RH) variation is reported. The submillimeter-sized GaN device exhibits a high sensitivity of 13.2 nA/%RH at 2-70%RH and 61.5 nA/%RH at 70-90%RH, and a fast response/recovery time of 12.5 s/6 s. With the integration of a wireless data transmission module and the assistance of machine learning based on 1-D convolutional neural networks, seven breathing patterns are identified with an overall classification accuracy of >96%. This integrated and flexible on-mask sensing platform successfully demonstrates real-time and intelligent respiratory monitoring capability, showing great promise for practical healthcare applications.

Wireless Self-Powered High-Performance Integrated Nanostructured-Gas-Sensor Network for Future Smart Homes.

The accelerated evolution of communication platforms including Internet of Things (IoT) and the fifth generation (5G) wireless communication network makes it possible to build intelligent gas sensor networks for real-time monitoring chemical safety and personal health. However, this application scenario requires a challenging combination of characteristics of gas sensors including small formfactor, low cost, ultralow power consumption, superior sensitivity, and high intelligence. Herein, self-powered integrated nanostructured-gas-sensor (SINGOR) systems and a wirelessly connected SINGOR network are demonstrated here. The room-temperature operated SINGOR system can be self-driven by indoor light with a Si solar cell, and it features ultrahigh sensitivity to H2, formaldehyde, toluene, and acetone with the record low limits of detection (LOD) of 10, 2, 1, and 1 ppb, respectively. Each SINGOR consisting of an array of nanostructured sensors has the capability of gas pattern recognition and classification. Furthermore, multiple SINGOR systems are wirelessly connected as a sensor network, which has successfully demonstrated flammable gas leakage detection and alarm function. They can also achieve gas leakage localization with satisfactory precision when deployed in one single room. These successes promote the development of using nanostructured-gas-sensor network for wide range applications including smart home/building and future smart city.

A Wearable Nutrition Tracker.

Nutrients are essential for the healthy development and proper maintenance of body functions in humans. For adequate nourishment, it is important to keep track of nutrients level in the body, apart from consuming sufficient nutrition that is in line with dietary guidelines. Sweat, which contains rich chemical information, is an attractive biofluid for routine non-invasive assessment of nutrient levels. Herein, a wearable sensor that can selectively measure vitamin C concentration in biofluids, including sweat, urine, and blood is developed. Detection through an electrochemical sensor modified with Au nanostructures, LiClO4 -doped conductive polymer, and an enzymes-immobilized membrane is utilized to achieve wide detection linearity, high selectivity, and long-term stability. The sensor allows monitoring of temporal changes in vitamin C levels. The effect of vitamin C intake on the sweat and urine profile is explored by monitoring concentration changes upon consuming different amounts of vitamin C. A longitudinal study of sweat's and urine's vitamin C correlation with blood is performed on two individuals. The results suggest that sweat and urine analysis can be a promising method to routinely monitor nutrition through the sweat sensor and that this sensor can facilitate applications such as nutritional screening and dietary intervention.

A biomimetic eye with a hemispherical perovskite nanowire array retina.

Human eyes possess exceptional image-sensing characteristics such as an extremely wide field of view, high resolution and sensitivity with low aberration1. Biomimetic eyes with such characteristics are highly desirable, especially in robotics and visual prostheses. However, the spherical shape and the retina of the biological eye pose an enormous fabrication challenge for biomimetic devices2,3. Here we present an electrochemical eye with a hemispherical retina made of a high-density array of nanowires mimicking the photoreceptors on a human retina. The device design has a high degree of structural similarity to a human eye with the potential to achieve high imaging resolution when individual nanowires are electrically addressed. Additionally, we demonstrate the image-sensing function of our biomimetic device by reconstructing the optical patterns projected onto the device. This work may lead to biomimetic photosensing devices that could find use in a wide spectrum of technological applications.

Nicotine Monitoring with a Wearable Sweat Band.

The tobacco epidemic is a public health threat that has taken a heavy toll of lives around the globe each year. Smoking affects both the smokers and those who are exposed to secondhand smoke, and careful tracking of exposure can be key to mitigating the potential hazards. For smokers, the variation of chemical compositions between commercial cigarettes has led to ambiguity in estimating the health risks, both for active smokers and others involuntarily exposed to tobacco smoke and byproducts. In this regard, sweat possesses an attractive opportunity to monitor smoke exposure due to sweat's abundance in biomolecules and its great accessibility. Here, we present a wearable sweat band to monitor nicotine, a prominent ingredient in cigarettes, as a viable way to quantitatively assess a wearer's exposure to smoking. Both smokers and normal subjects are tested to demonstrate the use of this device for smoke-related health monitoring. Our results exhibit confirmable and elevated nicotine levels in sweat for subjects inhaling cigarette smoke. This continuous and personalized sweat sensing device is leverage to monitor smoke pollution for a potentially broad population.

Regional and correlative sweat analysis using high-throughput microfluidic sensing patches toward decoding sweat.

Recent technological advancements in wearable sensors have made it easier to detect sweat components, but our limited understanding of sweat restricts its application. A critical bottleneck for temporal and regional sweat analysis is achieving uniform, high-throughput fabrication of sweat sensor components, including microfluidic chip and sensing electrodes. To overcome this challenge, we introduce microfluidic sensing patches mass fabricated via roll-to-roll (R2R) processes. The patch allows sweat capture within a spiral microfluidic for real-time measurement of sweat parameters including [Na+], [K+], [glucose], and sweat rate in exercise and chemically induced sweat. The patch is demonstrated for investigating regional sweat composition, predicting whole-body fluid/electrolyte loss during exercise, uncovering relationships between sweat metrics, and tracking glucose dynamics to explore sweat-to-blood correlations in healthy and diabetic individuals. By enabling a comprehensive sweat analysis, the presented device is a crucial tool for advancing sweat testing beyond the research stage for point-of-care medical and athletic applications.

Wearable Sweat Band for Noninvasive Levodopa Monitoring.

Levodopa is the standard medication clinically prescribed to patients afflicted with Parkinson's disease. In particular, the monitoring and optimization of levodopa dosage are critical to mitigate the onset of undesired fluctuations in the patients' physical and emotional conditions such as speech function, motor behavior, and mood stability. The traditional approach to optimize levodopa dosage involves evaluating the subjects' motor function, which has many shortcomings due to its subjective and limited quantifiable nature. Here, we present a wearable sweat band on a nanodendritic platform that quantitatively monitors levodopa dynamics in the body. Both stationary iontophoretic induction and physical exercise are utilized as our methods of sweat extraction. The sweat band measures real-time pharmacokinetic profiles of levodopa to track the dynamic response of the drug metabolism. We demonstrated the sweat band's functionalities on multiple subjects with implications toward the systematic administering of levodopa and routine management of Parkinson's disease.

A Fully Integrated and Self-Powered Smartwatch for Continuous Sweat Glucose Monitoring.

Wearable devices for health monitoring and fitness management have foreseen a rapidly expanding market, especially those for noninvasive and continuous measurements with real-time display that provide practical convenience and eliminated safety/infection risks. Herein, a self-powered and fully integrated smartwatch that consists of flexible photovoltaic cells and rechargeable batteries in the forms of a "watch strap", electrochemical glucose sensors, customized circuits, and display units integrated into a "dial" platform is successfully fabricated for real-time and continuous monitoring of sweat glucose levels. The functionality of the smartwatch, including sweat glucose sensing, signal processing, and display, can be supported with the harvested/converted solar energy without external charging devices. The Zn-MnO2 batteries serve as intermediate energy storage units and the utilization of aqueous electrolytes eliminated safety concerns for batteries, which is critical for wearable devices. Such a wearable system in a smartwatch fashion realizes integration of energy modules with self-powered capability, electrochemical sensors for noninvasive glucose monitoring, and in situ and real-time signal processing/display in a single platform for the first time. The as-fabricated fully integrated and self-powered smartwatch also provides a promising protocol for statistical study and clinical investigation to reveal correlations between sweat compositions and human body dynamics.

A strategy for screening trypsin inhibitors from traditional Chinese medicine based on a monolithic capillary immobilized enzyme reactor coupled with offline liquid chromatography and mass spectrometry.

A novel strategy was successfully developed for screening trypsin inhibitors in traditional Chinese medicines based on monolithic capillary immobilized enzyme reactors combined with liquid chromatography-tandem mass spectrometry. Organic polymer based monolithic enzyme reactors were firstly prepared by covalently bonding trypsin to a poly(glycidyl methacrylate-co-poly (ethylene glycol) diacrylate) monolith by the ring-opening reaction of epoxy groups. The activity and kinetic parameters of the obtained monolithic trypsin reactors were systematically evaluated using micro-liquid chromatography. Fourier transform infrared spectroscopy and scanning electron microscopy were also used to characterize the monolithic trypsin reactors. The resulting functional and denatured monolithic trypsin reactors were applied as affinity solid-phase extraction columns, and offline coupled with a liquid chromatography-tandem mass spectrometry system to construct a binding affinity screening platform. Subsequently, the proposed platform was applied for screening trypsin binders in a Scutellaria baicalensis Georgi extract. Three compounds, namely scutellarin, baicalin, and wogonoside were identified, and their inhibitory activities were further confirmed via an in vitro enzymatic inhibition assay. Additionally, molecular docking was also performed to study the interactions between trypsin and these three compounds.

Increasing Photoluminescence Quantum Yield by Nanophotonic Design of Quantum-Confined Halide Perovskite Nanowire Arrays.

High-photoluminescence quantum yield (PLQY) is required to reach optimal performance in solar cells, lasers, and light-emitting diodes (LEDs). Typically, PLQY can be increased by improving the material quality to reduce the nonradiative recombination rate. It is in principle equally effective to improve the optical design by nanostructuring a material to increase light out-coupling efficiency (OCE) and introduce quantum confinement, both of which can increase the radiative recombination rate. However, increased surface recombination typically minimizes nanostructure gains in PLQY. Here a template-guided vapor phase growth of CH3NH3PbI3 (MAPbI3) nanowire (NW) arrays with unprecedented control of NW diameter from the bulk (250 nm) to the quantum confined regime (5.7 nm) is demonstrated, while simultaneously providing a low surface recombination velocity of 18 cm s-1. This enables a 56-fold increase in the internal PLQY, from 0.81% to 45.1%, and a 2.3-fold increase in OCEy to increase the external PLQY by a factor of 130, from 0.33% up to 42.6%, exclusively using nanophotonic design.

Efficient metal halide perovskite light-emitting diodes with significantly improved light extraction on nanophotonic substrates.

Metal halide perovskite has emerged as a promising material for light-emitting diodes. In the past, the performance of devices has been improved mainly by optimizing the active and charge injection layers. However, the large refractive index difference among different materials limits the overall light extraction. Herein, we fabricate efficient methylammonium lead bromide light-emitting diodes on nanophotonic substrates with an optimal device external quantum efficiency of 17.5% which is around twice of the record for the planar device based on this material system. Furthermore, optical modelling shows that a high light extraction efficiency of 73.6% can be achieved as a result of a two-step light extraction process involving nanodome light couplers and nanowire optical antennas on the nanophotonic substrate. These results suggest that utilization of nanophotonic structures can be an effective approach to achieve high performance perovskite light-emitting diodes.

Printable Fabrication of a Fully Integrated and Self-Powered Sensor System on Plastic Substrates.

Wearable and portable devices with desirable flexibility, operational safety, and long cruising time, are in urgent demand for applications in wireless communications, multifunctional entertainments, personal healthcare monitoring, etc. Herein, a monolithically integrated self-powered smart sensor system with printed interconnects, printed gas sensor for ethanol and acetone detection, and printable supercapacitors and embedded solar cells as energy sources, is successfully demonstrated in a wearable wristband fashion by utilizing inkjet printing as a proof-of-concept. In such a "wearable wristband", the harvested solar energy can either directly drive the sensor and power up a light-emitting diode as a warning signal, or can be stored in the supercapacitors in a standby mode, and the energy released from supercapacitors can compensate the intermittency of light illumination. To the best of our knowledge, the demonstration of such a self-powered sensor system integrated onto a single piece of flexible substrate in a printable and additive manner has not previously been reported. Particularly, the printable supercapacitors deliver an areal capacitance of 12.9 mF cm-2 and the printed SnO2 gas sensor shows remarkable detection sensitivity under room temperature. The printable strategies for device fabrication and system integration developed here show great potency for scalable and facile fabrication of a variety of wearable devices.

Recent advances in bio-affinity chromatography for screening bioactive compounds from natural products.

Natural products are one of the most important sources of leading compounds in drug discovery. Until now, rapid screening and identification of biologically active components from natural products remain a technical challenge. Bio-affinity chromatography (BAC) based approaches hold great promise in screening potential bioactive ligands from complex samples. In this review, we summarized recent development of BAC in natural products screening, with a particular emphasis on the reported bio-affinity stationary phases and chromatographic supports as well as the applications of BAC coupled with GC-MS or LC-MS.