Sweat, an abundant biofluid containing rich source of physiological and metabolic information regarding the health of an individual, with the potential for noninvasive extraction. Health monitoring via quantitative sweat analysis could potentially preclude the need for periodic blood sample assessments. Continuous monitoring of key electrolytes such as sodium can provide a wide range of information from electrolyte imbalance to diagnosis of cystic fibrosis. This makes the quantification of sodium ions important since the loss of sodium could lead to hyponatremia. About 5% of the adults and about 35% of hospitalized patients suffer from hyponatremia which makes it one of the most common electrolyte disorder. Therefore, developing a robust sensing platform is indispensable. A flexible, thin class of microfluidic device has been introduced of late, that can be used for sweat extraction and quantifiable monitoring of the sweat analytes. However, these devices operate with high cost, complex design, and an active power source. Therefore, in our study, we address such challenges by developing a triboelectric nanogenerator (TENG) based self-powered microfluidic device that works on contact electrification. The wearable microfluidic device monitors the sodium levels in the sweat of the individual extracted in a non-invasive manner. The flexible microfluidic channel utilizes the capillary action generated with the periodic finger tapping to transport the sweat from skin to the sensing area. The transported sweat is used in the liquid - solid interaction between the sweat and microfluidic channels with electrode coated with ion selective membrane (ISM) to obtain triboelectric output. The ISM coating on the electrode is able to selectively detect the target analyte which results in a significant difference in output. This study demonstrates a flexible microfluidic based self-powered noninvasive sweat sensor which has potential applications in analysis of electrolyte loss through sweat.

In deserts, sedimentation from frequent dust activities on solar cells poses a substantial technical challenge, reducing efficiency and necessitating advanced cost-inefficient cleaning mechanisms. Herein, a novel sandfish scale-inspired self-healing fluorinated copolymer-based triboelectric layer is directly incorporated on top of the polysilicon solar cell for sustained hybrid energy harvesting. The transparent biomimetic layer, with distinctive saw-tooth microstructured morphology, exhibits ultra-low sand adhesion and high abrasion-resistant properties, inhibits sedimentation deposition on solar cells, and concurrently harvests kinetic energy from wind-driven sand particles through triboelectric nanogenerator (TENG). The film exhibits a low friction coefficient (0.149), minimal sand adhesion force (27 nN), and a small wear area (327 mu m2). In addition, over 2 months, a solar cell with the sandfish scale-inspired structure demonstrates only a 16% decline in maximum power output compared to the bare solar cell, which experiences a 60% decline. Further, the sandfish scale-based TENG device's electrical output is fully restored to its original value after a 6-h self-healing cycle and maintains consistent stable outputs. These results highlight the exceptional advantages of employing biomimetic self-healing materials as robust triboelectric layers, showcasing sustained device stability and durability for prolonged use in harsh desert environments, ultimately contributing to a low cost-of-electricity generation paradigm. Herein, a sandfish scale-inspired self-healing fluorinated copolymer-based triboelectric layer is seamlessly integrated on top of a polysilicon solar cell to concurrently harvest both solar energy and kinetic energy associated with wind-driven sand particles via a triboelectric nanogenerator. The biomimetic triboelectric layer leverages ultra-low sand adhesion and high abrasion-resistant characteristics inherent in the sandfish scales' distinct saw-tooth morphology. image

Solid-liquid triboelectric nanogenerators (SL-TENGs) exhibit significant potential in energy harvesting and sensing. This review explores SL-TENG development, focusing on chemical sensing and biosensing applications. Initially, the working mechanisms of various SL-TENG modes are described. Subsequently, an analysis of surface modifications of contact surfaces and liquids to functionalize chemical sensing and biosensing is explored, including their impact on surface properties and the corresponding effect on device performance related to sensing applications.

Biomarkers based sensing in the realm of disease prevention, its diagnosis, and drug development has shown its unique importance in health care. In particular, the platelet level in blood is strongly linked with the development of several kind of severe diseases like coronavirus disease 2019, diabetes, and microbial infections as well as individuals undergoing cancer diagnosis. Currently, commercial methods employed for platelet level determination in whole-blood are based on Coulter principle, flow cytometry, and image analysis. However, these technologies are intricate, time consuming, expensive, and require a trained operator as well as lack of portability. Considering these issues, we have developed a self-powered portable device for real-time platelet level monitoring, aimed towards point-of-care applications. The fabricated self-powered-microfluidic triboelectric nanogenerator (SPM-TENG) utilized test sample flow-resistance for sensing of platelet level and triboelectric voltage output as sensing signal. For the fine tuning of fabricated SPM-TENG, we compared the triboelectric voltage output from gold electrode measurement setup and terminal electrode measurement setup. In view of further improvement in stability, voltage output and to minimize the noise in sensing signals, the geometrical optimization of microfluidic channel was performed. In conclusion we have optimized the device as a terminal electrode measurement setup with copper tubes on terminals of microfluidic channel and copper oxide nanowires grown on the interior of copper tubes. These copper oxide nanowires provide a high surface area for solid-liquid contact separation and is responsible for enhanced sensing signal. The fabricated SPM-TENG has shown its great potential in platelet level sensing with plasma-based samples as well as whole-blood samples. The proposed device demonstrated its practicality towards real-time rapid sensing of platelet level and portability.

Traditional drug delivery systems lack the potential of controlled drug release, thereby decreasing drug utilization and release efficiency. Herein, a next generation of stimuli-responsive drug delivery platform is designed based on piezocatalytic molybdenum disulfide nanoflowers (MoS2 NFs) which can be triggered by ultrasound (US) stimulation for effective acute inflammation therapy. Under US irradiation, MoS2 NFs undergoes piezocatalysis to generate reactive oxygen species (ROS) owing to piezoelectric polarization, thus releasing loaded anti-inflammatory drug Indomethacin (IND) to the targeted inflammation site. The cumulative release of IND elevated significantly with the increase in the duration for US exposure due to the amplified ROS generation, which displayed a highly controllable nature of the as-designed drug delivery platform. For convenient applications, the IND loaded MoS2 NFs (IND@MoS2 NFs) was functionalized onto commercial dressings and their tunable in-vivo drug release performance was demonstrated in paw edema model. IND@MoS2 NFs upon US irradiation, controllably released IND into the site-specific inflamed paw which significantly inhibited 56% of paw swelling in 6 h by suppressing the infiltration of neutrophils and expression of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α). The highly controllable drug delivery system holds great potential in facilitating personalized, user-friendly theranostic applications with improved patient outcomes.

The integration of the Internet of Things (IoT) with advanced sensing technologies is transforming environmental monitoring and public health protection. In this study, a fully self-powered and automated chemical sensing system is developed and integrated with a robotic hand for "touch and sense" detection of toxic heavy metal ions (Pb2⁺, Cr⁶⁺, As3⁺) in aquatic environments. The system combines a self-powered solid-liquid triboelectric nanosensor (SL-TENS) with a thermoelectric generator (TEG), which harnesses ambient heat to power the robotic hand, eliminating the need for external power sources. The robotic hand is controlled wirelessly via an exo-hand, minimizing the risk of exposure during remote monitoring. The sensing component uses copper oxide nanowires (CuO NWs) coated with ion-selective membranes (ISMs) to enhance triboelectric output and enable highly selective ion detection. The system demonstrates effective real-time, on-site detection in lake water and data transmitted wirelessly to the user. This innovative approach provides a highly safe and efficient method for detecting hazardous pollutants in difficult-to-access areas, offering significant potential for wireless and real-time environmental monitoring and hazard prevention, thus contributing to the safeguarding of human health. This study presents a novel advancement in the field of IoT-enabled environmental monitoring systems.

Blood platelet count signiflcantly affects the development of severe conditions like myocardial infarction, peripheral arterial ischemia, respiratory compromise, stroke, diabetes, coronavirus disease 2019 (COVID-19), along with chemotherapy patients and those suffering cardiovascular diseases (CVDs). These conditions necessitate frequent monitoring of platelet counts to guide diagnostic and therapeutic decisions. However, existing techniques are relatively time-consuming, lack of accuracy and require precise operation. The emergence of these severe diseases underscored the need to develop advanced platelet count-monitoring techniques which are rapid, highly precise, and conveniently portable for point-of-care applications. In this study, we emphasized the development of a triboelectric microfluidic nanosensor (TMNS) for platelet quantiflcation through the assessment of flow resistance. The functionality of TMNS device is based on immobilization of platelets on a collagen layer coated inside a microfluidic channel. The triboelectric voltage output is measured as a detection signal of the flow resistance and is enhanced by incorporating high surface area copper oxide nanowires (CuO NWs) on the interior of copper tubes. These copper tubes serve as terminal electrodes and for flow guiding. The flow resistance of plasma solutions is elevated when the platelet concentration increases due to heightened adherence of platelets onto the collagen layer. Variations in flow resistance induce alterations in contact electriflcation, causing changes in output voltage at load terminals. Fine-tuning of the TMNS device was achieved by optimizing the channel width and length, flowing liquid viscosity, and voltage measurement technique. Platelet quantiflcation sensing data were acquired through the combination of platelet-rich plasma (PRP) and platelet-poor plasma (PPP) solutions. The described device exhibits promising capabilities for platelet-count monitoring in whole-blood samples collected from three distinct patient groups, showcasing its potential impact in precise point-of-care applications.

In recent years, numerous photocatalysts and electrocatalysts have been developed to address energy and environmental issues, however, some properties such as low efficiency and easy charge recombination limit their applications. Hence, it is imperative to design and explore new catalytic techniques that include non-photoresponsive catalysts. Here, recent advances in exploiting diverse catalytic techniques that can be used in dark environments, including piezocatalysis, thermocatalysis, pyrocatalysis, tribocatalysis and hybrid catalysis (piezocatalysis with pyrocatalysis and tribocatalysis with pyrocatalysis) are summarized. The overall mechanism of each catalytic technique and its applications in different fields such as energy generation, environmental remediation, and carbon dioxide reduction are discussed. More information can be found in the Review by Zong-Hong Lin, Sangmin Lee, Dukhyun Choi et al.

The outbreak of pandemics (e.g., severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 in 2019), influenza A viruses (H1N1 in 2009), etc.), and worldwide spike in the aging population have created unprecedented urgency for developing new drugs to improve disease treatment. As a result, extensive efforts have been made to design novel techniques for efficient drug monitoring and screening, which form the backbone of drug development. Compared to traditional techniques, microfluidics-based platforms have emerged as promising alternatives for high-throughput drug screening due to their inherent miniaturization characteristics, low sample consumption, integration, and compatibility with diverse analytical strategies. Moreover, the microfluidic-based models utilizing human cells to produce in-vitro biomimetics of the human body pave new ways to predict more accurate drug effects in humans. This review provides a comprehensive summary of different microfluidics-based drug sensing and screening strategies and briefly discusses their advantages. Most importantly, an in-depth outlook of the commonly used detection techniques integrated with microfluidic chips for highly sensitive drug screening is provided. Then, the influence of critical parameters such as sensing materials and microfluidic platform geometries on screening performance is summarized. This review also outlines the recent applications of microfluidic approaches for screening therapeutic and illicit drugs. Moreover, the current challenges and the future perspective of this research field is elaborately highlighted, which we believe will contribute immensely towards significant achievements in all aspects of drug development.

Catalysis plays a crucial role in all the major applications and challenges in the environment, including energy generation and environmental remediation. Although photocatalysts and electrocatalysts are useful in addressing energy and environmental issues, they have some major drawbacks, such as low efficiency and easy charge recombination which limits their applications. Hence, it is imperative to design and explore new catalytic techniques that include non-photoresponsive catalysts. In this review, the detailed possibilities, characteristics and prospects of non-photoresponsive catalysts, such as piezocatalysts, thermocatalysts, pyrocatalysts, and tribocatalysts along with hybrid catalysts are described. The overall mechanism of each catalytic technique and its applications in different fields such as energy generation, environmental remediation, and carbon dioxide reduction are discussed.

Platelet number plays an important role in several kinds of diseases such as leukemia, hepatitis C, diabetes, COVID-19, microbial infections, etc. These diseases can result in thrombocytopenia, a condition where patients suffer from reduced platelets, thus requiring the need to frequently monitor the platelet count. Currently existing techniques are complex, costly, and time consuming. The target diseases continue to evolve urging the need to develop rapid, facile point-of-care devices with high precision. In this regard, the current study is focused on the development of a platelet quantification technique based on trapping of platelets in a microfluidic channel adhered with collagen layer, and CuO NWs grown on Cu tube integrated on both the sides of the channel. This trapping of platelets results in a change in the triboelectric output performance from solid-liquid contact electrification due to change in flow rate of platelet content in the plasma. These changes in triboelectric output are enhanced by CuO NWs due to its high surface-area-to-volume ratio. The study of flow sensing by integrating the microfluidic device with solid-liquid contact electrification has been reported for the first time. The flow sensing signal was optimized by variation in viscosity of the flowing liquid, channel geometry, flow rate, and triboelectric voltage measuring methods. The platelet rich plasma (PRP) and platelet poor plasma (PPP) were prepared and mixed in different ratios to prepare the solutions with different concentration of platelets (0% - 100%). The calibration curve for platelet quantification has shown a variation of 9 V for change in platelet concentration from 0% to 100%. The proposed device exhibited a linear response with the variation in platelet counts. The obtained results prove its potential and feasibility as a point-of-care device.

This study introduces a general label-free drug screening platform with potential to support high-throughput drug screening for any protein target. Its innovation lies in quantifying the affinity of molecule-molecule interactions via voltage output variation, which achieves unprecedented selectivity and sensitivity. It combines computational analysis complemented by experimental substantiation with a solid-liquid triboelectric nanosensor. Owing to its high binding affinity, FKBP-rapamycin is used as a model system to demonstrate the platform's sensitivity. Subsequently, the research is extended to study drug interactions with an oncogenic protein ATG4B. The findings unveil the binding of S130 and Tioconazole to ATG4B, a critical cysteine protease involved in autophagy, while revealing that Dexamethasone does not bind ATG4B. This binding exerts a specific inhibitory effect on autophagic flux and triggers cancer cell apoptosis. The results support the previously verified inhibitory effects of these drugs and the effectiveness of a newly developed self-powered drug screening platform, leveraging the principles of solid-liquid contact electrification. This approach adeptly confronts enduring challenges in traditional drug development methods where biochemical assays need to be designed for each individual protein target or only time-consuming and concentration-demanding molecular interaction measurements were made available.

Real-time gait monitoring is crucial for neuromuscular diagnosis and rehabilitation of neuromuscular ailments. However, the existing wearable sensors for gait analysis suffer from several drawbacks, such as external power requirement, poor sensitivity, short-term stability, and professional operator requirement, which restrict their applicability outside clinical settings. Here, a next-generation self-powered solid-liquid triboelectric nanogenerator-based flexible wearable sensor is developed. The proposed sensor is composed of a highly resilient liquid metal encapsulated within an innovative bio-mimicked shark skin-like microstructure embedded on the Ecoflex surface. The unique surface morphology imparts hydrophobicity to the solid triboelectric layer, which prevents the liquid metal adhesion during sensing and facilitates highly sensitive real-time monitoring of signals and long-term stability. The as-designed low-cost, highly scalable self-powered sensor, which is also compatible with diverse detection strategies, provides an on-demand user-friendly point-of-care gait detection and rehabilitation monitoring system with significant applications in personalized health care and sports science.

Given the huge economic burden caused by chronic and acute diseases on human beings, it is an urgent requirement of a cost-effective diagnosis and monitoring process to treat and cure the disease in their preliminary stage to avoid severe complications. Wearable biosensors have been developed by using numerous materials for non-invasive, wireless, and consistent human health monitoring. Graphene, a 2D nanomaterial, has received considerable attention for the development of wearable biosensors due to its outstanding physical, chemical, and structural properties. Moreover, the extremely flexible, foldable, and biocompatible nature of graphene provide a wide scope for developing wearable biosensor devices. Therefore, graphene and its derivatives could be trending materials to fabricate wearable biosensor devices for remote human health management in the near future. Various biofluids and exhaled breath contain many relevant biomarkers which can be exploited by wearable biosensors non-invasively to identify diseases. In this article, we have discussed various methodologies and strategies for synthesizing and pattering graphene. Furthermore, general sensing mechanism of biosensors, and graphene-based biosensing devices for tear, sweat, interstitial fluid (ISF), saliva, and exhaled breath have also been explored and discussed thoroughly. Finally, current challenges and future prospective of graphene-based wearable biosensors have been evaluated with conclusion. Graphene is a promising 2D material for the development of wearable sensors. Various biofluids (sweat, tears, saliva and ISF) and exhaled breath contains many relevant biomarkers which facilitate in identify diseases. Biosensor is made up of biological recognition element such as enzyme, antibody, nucleic acid, hormone, organelle, or complete cell and physical (transducer, amplifier), provide fast response without causing organ harm.

Wearable electrochemical sensors that can detect chemical analytes non-invasively are a fast developing next-generation digital-health technology. Because of their excellent performance, intrinsic compactness, and low cost, electrochemical-based sensors are capable of detecting biomarkers through a non-invasive approach for the continuous monitoring of real-time health status, which holds a lot of potential as wearable sensors for a tremendous promise for a plethora of applications. These wearable electrochemical sensors have been incorporated into various materials systems and even directly on the epidermis for different monitoring purposes because of their unique potential to process chemical analytes in a minimal/non-invasive and non-obtrusive manner. With ongoing innovation and a focus on critical challenges, such minimal/non-invasive electrochemical biosensors are anticipated to open up a new exciting path in the field of wearable wireless sensing devices and body-sensor networks, and thus find abundant use in a wide range of personal healthcare monitoring as well as in sport and military applications. Hence, this review article examines current advancements and discoveries in the field of wearable biosensors, with a focus on a subset of these devices that can conduct very sensitive electrochemical analysis. Recent insights into novel sampling strategies, various electrochemical sensing mechanisms and power management techniques have been discussed in detail in this review article. Finally, present unmet challenges and opportunities in wearable electrochemical biosensors are explored to motivate future technological breakthroughs.

Triboelectric nanogenerators (TENGs) based energy harvesting is considered as a highly efficient approach for mechanical-to-electrical energy conversion based on contact electrification and electrostatic induction. Although triboelectrification is exhibited by almost all substances, chemists and material scientists have performed extensive investigations through theoretical analysis and practical applications to promote further development of TENGs. However, there are various parameters related to triboelectric materials and its output performance, which are required to be optimized for further improvement of efficiency and stability of TENGs. Especially, extensive research effort has been dedicated in engineering triboelectric materials to improve the output performance. However, the industrial application of TENG is still limited by low charging and power conversion efficiency. This review comprehensively discusses the recent progress in improvement of the output performance of TENGs based on different strategies and principles. Moreover, this review also suggests a holistic approach for the design and integration of charge boosting and power management with TENGs. The key impact of this review includes the discussion regarding physical and chemical modification based multidimensional engineering as well as different charge boosting, and power management strategies for the further advancement of TENGs. Moreover, the review also further introduces the applications of TENGs in emerging fields, such as wearable electronic devices and implantable medical devices. Finally, the challenges and future prospective are discussed, thereby guiding further research priorities.