Wearable and Implantable Cortisol-Sensing Electronics for Stress Monitoring

Perceived stress, risk factors and prognostic monitoring loci for the development of depression

This article examines stress and its potential role in the development of depression. By reviewing existing literature, the article explores the possible role of stress in diagnosing and monitoring depression and highlights the importance of managing personal stress in the treatment of depression. The article also discusses the many ways that stress and depression are connected, and suggests ideas for subsequent investigations. This includes developing more exact ways to measure biomarkers, exploring treatments that are not based on drugs, and looking at the effect that society has on depression.

Fully Wearable Devices for Real-Time Health Monitoring and Multimodal Sensing in Nanomedicine Using Multiplexed Green Biofuels

Fully wearable devices are crucial for real-time health monitoring, but existing devices often lack stable power, on-site signal processing, and multimodal sensing. To overcome these limitations, we introduce the first self-powered and fully wearable sensor (MESFW) based on multiplexed green biofuels. The MESFW integrates a microfluidic module, sensing module, laser-induced graphene (LIG) electrodes, and customized electronics, enabling highly sensitive detection of glucose and alcohol in noninvasive biofluids (sweat, breath, saliva, tears) while monitoring daily activities (temperature, pressure, touch). Experiments show the MESFW can track glucose and alcohol levels before and after meals/drinking, powered continuously for 24 h. With machine learning, it accurately identifies wearing types and enables real-time health prediction. This innovation offers a novel approach to real-time physiological monitoring.

Smart Bioelectronics for Real-Time Diagnosis and Therapy of Body Organ Functions

Noncommunicable diseases (NCDs) associated with cardiovascular, neurological, and gastrointestinal disorders remain a leading cause of global mortality, sounding the alarm for the urgent need for better diagnostic and therapeutic solutions. Wearable and implantable biointegrated electronics offer a groundbreaking solution, combining real-time, high-resolution monitoring with innovative treatment capabilities tailored to specific organ functions. In this comprehensive review, we focus on the diseases affecting the brain, heart, gastrointestinal organs, bladder, and adrenal gland, along with their associated physiological parameters. Additionally, we provide an overview of the characteristics of these parameters and explore the potential of bioelectronic devices for in situ sensing and therapeutic applications and highlight the recent advancements in their deployment across specific organs. Finally, we analyze the current challenges and prospects of implementing closed-loop feedback control systems in integrated sensor-therapy applications. By emphasizing organ-specific applications and advocating for closed-loop systems, this review highlights the potential of future bioelectronics to address physiological needs and serves as a guide for researchers navigating the interdisciplinary fields of diagnostics, therapeutics, and personalized medicine.

Heparin Doped Polyaniline for Anticoagulation Supercapacitors

With the rapid development of implantable electronic medical devices, supercapacitors have gained significant attention as implantable energy storage devices due to their inherent advantages. However, these devices inevitably direct contact with blood and trigger coagulation or thrombus formation when implanted in the body. In severe cases, these negative effects compromise the functionality of the implantable energy storage system and even jeopardize human health. Herein, a biocompatible electrode material with high anticoagulant activity is designed by doping polyaniline with anticoagulant macromolecule heparin under neutral conditions, which macromolecules as dopants under neutral conditions not only avoids the toxicity of acids to biological tissues and de-doping caused by small molecules, but also imparts high anticoagulant properties to the material. Based on the electrode material and in situ polymerization approach, an all-in-one anticoagulation supercapacitor is employed to manufacture and exhibits good electrochemical performance (energy density of 18.89 µWh cm-2 and a power density of 197.8 µW cm-2), cycling stability (capacitance retention of 70.23% after 2, 000 cycles), anticoagulant performance (APTT is 15.47 s, PT is 16.57 s, TT is 49.47 s, and FIB is 1.12 g L-1), and tissue compatibility. The doping strategy provides a valuable reference for energy supply in implantable bioelectronics.

A portable sweat biosensor for multiple chronic kidney diseases biomarkers detection

Continuous and quantitative measurement of toxin biomarkers in biological fluids constitutes a significant advancement in the proactive management of chronic kidney diseases (CKD). Although sweat analysis presents a promising non-invasive strategy, conventional detection methods suffer from inherent limitations, including low sensitivity, poor specificity, high cost, and inadequate long-term durability. Herein, we constructed a novel molecularly imprinted portable biosensor that can simultaneously detect three critical biomarkers (urea, creatinine, and uric acid) for CKD in human sweat. The sensor was fabricated on flexible polyethylene terephthalate (PET) film using screen-printing technology to form a five-electrode array consisting of one counter electrode, one reference electrode and three working electrodes. The ternary composite electrodes (NiCoMOF/MWCNTs/NCDs) were designed as sensing substrate, the porous structure derived from metal-organic frameworks provides abundant active sites for analyte sensing and in synergy with the conductivity of MWCNTs and NCDs, endows the ternary composite electrode with a high electrochemically active surface area (A) of 0.062 cm2, a rapid electron transfer rate (k0) of 6.685 × 10-3 cm s-1, and a low electron transfer resistance of 52.79 Ω, significantly enhancing its electrochemical properties (Bare carbon, A: 0.0161 cm2, k0: 0.613 × 10-3 cm s-1). Molecular imprinting technology generates highly specific recognition cavities with enhanced rebinding efficiency by removing template molecules from each working electrode. The portable sensing platform exhibits sensitivities of 6.2 μA mM-1 cm-2, 134 nA μM-1 cm-2, and 1870 nA μM-1 cm-2 for the detection of urea, creatinine, and uric acid, respectively, with detection limits of 0.048 mM, 0.032 μM, and 0.024 μM. The linear ranges encompass the physiological concentrations of these analytes in sweat, with corresponding correlation coefficients (R2) of 0.9959, 0.9952, and 0.9981. The non-enzymatic mechanism ensures that the signal retention rate remains above 95.8 % after 60 days of storage. The results from various scenario tests demonstrated that the sensing system successfully achieved synchronous dynamic monitoring of three biomarkers in sweat samples. Hence, this work shows high development prospects for a continuous, convenient, non-invasive sensing platform for point-of-care diagnosis and personalized management of chronic kidney diseases.

Innovations in graphene-based electrochemical biosensors in healthcare applications

The isolation of a single atomic layer of graphite, known as graphene, marked a fundamental moment that transformed the field of materials science. Graphene-based nanomaterials are recognized for their superior biocompatibility compared with many other types of nanomaterials. Moreover, one of the main reasons for the growing interest in graphene is its potential applications in emerging technologies. Its key characteristics, including high electrical conductivity, excellent intrinsic charge carrier mobility, optical transparency, substantial specific surface area, and remarkable mechanical flexibility, position it as an ideal candidate for applications in solar cells and touch screens. Its durability further establishes graphene as a strong contender for developing robust materials. To date, a variety of methods, such as traditional spectroscopic techniques and chromatographic approaches, have been developed for detecting biomolecules, drugs, and heavy metals. Electrochemical methods, known for their portability, selectivity, and impressive sensitivity, offer considerable convenience for both patients and professionals in point-of-care diagnostics. Recent advancements have significantly improved the capacity for rapid and accurate detection of analytes in trace amounts, providing substantial benefits in biosensor technology. Additionally, the integration of nanotechnology has markedly enhanced the sensitivity and selectivity of electrochemical sensors, yielding significantly improved results. Innovations such as point-of-care, lab-on-a-chip, implantable devices, and wearable sensors are discussed in this review.

Biosensors and Biomarkers for the Detection of Motion Sickness

Motion sickness (MS) is a prevalent syndrome that predominantly occurs during transportation and virtual reality (VR). The absence of reliable indicators and detection methods makes precise diagnosis difficult. Biomarker concentrations and trends may imply individual susceptibility, symptom classification, and the specific progression of MS. It is therefore essential to explore biosensors capable of providing sensitive, accurate, and real-time monitoring of biomarkers. This review provides a summary of the pathogenesis and biological pathways underlying MS, followed by an examination of biomarkers and their research progress. The most recent electrochemical biosensors developed for the non-invasive detection of representative biomarkers (e.g., cortisol, α-amylase, and estrogen) are comprehensively summarized. The effectiveness of these biosensors in practical application is discussed. It is anticipated that electrochemical biosensors can be gradually improved from the sampling methods, multimodal combinations, and data processing, which can facilitate the detection of MS toward individuation, refinement, and intelligence.

Advances in wearable electronics for monitoring human organs: Bridging external and internal health assessments

Devices used for diagnosing disease are often large, expensive, and require operation by trained professionals, which can result in delayed diagnosis and missed opportunities for timely treatment. However, wearable devices are being recognized as a new approach to overcoming these difficulties, as they are small, affordable, and easy to use. Recent advancements in wearable technology have made monitoring information possible from the surface of organs like the skin and eyes, enabling accurate diagnosis of the user's internal status. In this review, we categorize the body's organs into external (e.g., eyes, oral cavity, neck, and skin) and internal (e.g., heart, brain, lung, stomach, and bladder) organ systems and introduce recent developments in the materials and designs of wearable electronics, including electrochemical and electrophysiological sensors applied to each organ system. Further, we explore recent innovations in wearable electronics for monitoring of deep internal organs, such as the heart, brain, and nervous system, using ultrasound, electrical impedance tomography, and temporal interference stimulation. The review also addresses the current challenges in wearable technology and explores future directions to enhance the effectiveness and applicability of these devices in medical diagnostics. This paper establishes a framework for correlating the design and functionality of wearable electronics with the physiological characteristics and requirements of various organ systems.

Effects of Hydrogen-Rich Water on Growth, Redox Homeostasis and Hormonal, Histological and Immune Systems in Rats Exposed to High Cage Density Stress

OBJECTIVES

This study investigated the impact of drinking hydrogen-rich water (HRW) on growth performance, organ weights, thiol/disulphide homeostasis, oxidative status and some hormonal, histopathological and immunohistochemical changes in rats fed in a restricted housing environment.

METHODS

The eight groups (each group [male/female] eight rats) comprised two control, two hydrogen, two stress and two stress + hydrogen. All animals were given feed and water ad libitum for 3 months. Control and HRW group rats were calculated according to weight and housed according to the Guide's housing condition. The stress group and stress + HRW group were housed in half the area of the Guide's housing condition according to their weight. The animal's weekly body weights were measured throughout the study. The animals were sacrificed in accordance with ethical rules. Then, biochemical analyses were performed on thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), cortisol, parathyroid hormone (PTH) and calcium (Ca2+), total thiol (TT), native thiol (NT), disulphide, disulphide/TT × 100, disulphide/NT × 100 and NT/TT × 100, malondialdehyde (MDA) and glutathione (GSH). Haematoxylin staining for histopathological and SOD-2 immunoreactivity was also assessed.

RESULTS

Results showed that live weight gain was higher in the HRW groups than in the stress group. Oxidant status in biochemical analyses decreased in the stress + HRW group compared to the stress group. TSH decreased in the stress group. FT4, cortisol and Ca2+ increased in the stress group.

CONCLUSIONS

The stress-related physiological parameters were reduced in the HRW + stress group compared to the stress group. HRW could be suggested when the organism is found in stressful conditions.

Emerging Dual-Gate FET Sensor Paradigm for Ultra-Low Concentration Cortisol Detection in Complex Bioenvironments

Cortisol is a pivotal hormone regulating stress responses and is linked to various health conditions, making precise and continuous monitoring essential. Despite their non-invasive nature, conventional cortisol detection methods often suffer from inadequate sensitivity and reliability at low concentrations, limiting their diagnostic utility. To address these limitations, this study introduces a novel paradigm for high sensitivity cortisol detection using field-effect transistor (FET) sensors with dual-gate (DG) structures. The proposed sensor platform enhances sensitivity through capacitive coupling without requiring external circuits. Cortisol detection performance was evaluated by immobilizing monoclonal antibodies activated via 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide onto a SnO2 thin film-based extended-gate. The results revealed a sensitivity of 14.3 mV/dec in single-gate mode, which significantly increased to 243.8 mV/dec in DG mode, achieving a detection limit of 276 pM. Additionally, the reliability and stability of the sensor were validated by evaluating drift effects, confirming its ability to provide accurate detection even in artificial saliva environments containing interfering substances. In conclusion, the DG-FET-based cortisol detection approach developed in this study significantly outperforms conventional FET-based methods, enabling precise monitoring at ultra-low concentrations. This approach holds significant potential for diverse bioassays requiring high sensitivity and reliability in complex environments.

A Brief Review of Aptamer-Based Biosensors in Recent Years

Aptamers have recently become novel probes for biosensors because of their good biocompatibility, strong specificity, and high sensitivity. Biosensors based on peptides or nucleic acid aptamers are used in implantable and wearable devices owing to their ease of synthesis and economic efficiency. Simultaneously, amphoteric ionic peptides are being explored as antifouling layers for biosensors resistant to interference from extraneous proteins in serum. Thus, this paper reviews recently developed aptamer-based biosensors and introduces peptide- and nucleic acid-based biosensors, while focusing on the three primary classes of biosensors: electrochemical sensors, fluorescent or colorimetric biosensors, and electroluminescent sensors. Furthermore, we summarize their general construction strategies, describe specific electrochemical sensors that use peptides as an antipollution layer, and elucidate their advantages.

Current Strategies and Future Directions of Wearable Biosensors for Measuring Stress Biochemical Markers for Neuropsychiatric Applications

Most wearable biosensors aimed at capturing psychological state target stress biomarkers in the form of physical symptoms that can correlate with dysfunction in the central nervous system (CNS). However, such markers lack the specificity needed for diagnostic or preventative applications. Wearable biochemical sensors (WBSs) have the potential to fill this gap, however, the technology is still in its infancy. Most WBSs proposed thus far target cortisol. Although cortisol detection is demonstrated as a viable method for approximating the extent and severity of psychological stress, the hormone also lacks specificity. Multiplex WBSs that simultaneously target cortisol alongside other viable stress-related biochemical markers (SBMs) can prove to be indispensable for understanding how psychological stress contributes to the pathophysiology of neuropsychiatric illnesses (NPIs) and, thus, lead to the discovery of new biomarkers and more objective clinical tools. However, none target more than one SBM implicated in NPIs. Till this review, cortisol's connection to dysfunctions in the CNS, to other SBMs, and their implication in various NPIs has not been discussed in the context of developing WBS technology. As such, this review is meant to inform the biosensing and neuropsychiatric communities of viable future directions and possible challenges for WBS technology for neuropsychiatric applications.

Wearables in Chronomedicine and Interpretation of Circadian Health

Wearable devices have gained increasing attention for use in multifunctional applications related to health monitoring, particularly in research of the circadian rhythms of cognitive functions and metabolic processes. In this comprehensive review, we encompass how wearables can be used to study circadian rhythms in health and disease. We highlight the importance of these rhythms as markers of health and well-being and as potential predictors for health outcomes. We focus on the use of wearable technologies in sleep research, circadian medicine, and chronomedicine beyond the circadian domain and emphasize actigraphy as a validated tool for monitoring sleep, activity, and light exposure. We discuss various mathematical methods currently used to analyze actigraphic data, such as parametric and non-parametric approaches, linear, non-linear, and neural network-based methods applied to quantify circadian and non-circadian variability. We also introduce novel actigraphy-derived markers, which can be used as personalized proxies of health status, assisting in discriminating between health and disease, offering insights into neurobehavioral and metabolic status. We discuss how lifestyle factors such as physical activity and light exposure can modulate brain functions and metabolic health. We emphasize the importance of establishing reference standards for actigraphic measures to further refine data interpretation and improve clinical and research outcomes. The review calls for further research to refine existing tools and methods, deepen our understanding of circadian health, and develop personalized healthcare strategies.

Smart Bioelectronic Nanomesh Face Masks with Permeability and Flexibility for Monitoring Cortisol in Saliva

Bioelectronic face masks can easily collect biomarkers in saliva, in which free cortisol is abundant. However, conventional bioelectronic face masks involve significant challenges in terms of permeability and inhalation due to their nonpermeable film-type structure. Herein, we introduce a flexible and permeable nanomesh-based wearable biosensor designed for bioelectronic face masks that monitor cortisol levels. The diameter of the nanofiber matrix has a range of 200 to 500 nm and offers outstanding flexibility (2% resistance change at a bending radius of 2 mm), reliability (0.3% resistance change at a bending radius of 5 mm after 1000 bending cycles), and permeability (116.91 g m-2 h-1 at 18 °C with 40% humidity, which is 10 times higher compared with film) based on the nanoporous structure. We evaluated the electrochemical responses of functionalized interdigitated electrodes on a flexible and permeable poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanomesh. Our nanomesh cortisol biosensors demonstrated exceptional sensitivity to cortisol, even at low concentrations, with a detection limit as low as 10 pM. Furthermore, we measured cortisol in clinical samples, such as artificial saliva and human saliva, using nanomesh-based bioelectronic face masks. This study highlights the potential for further applications of bioelectronic face masks for detecting numerous biomarkers.

The Potential of Wearable Sensors for Detecting Cognitive Rumination: A Scoping Review

Cognitive rumination, a transdiagnostic symptom across mental health disorders, has traditionally been assessed through self-report measures. However, these measures are limited by their temporal nature and subjective bias. The rise in wearable technologies offers the potential for continuous, real-time monitoring of physiological indicators associated with rumination. This scoping review investigates the current state of research on using wearable technology to detect cognitive rumination. Specifically, we examine the sensors and wearable devices used, physiological biomarkers measured, standard measures of rumination used, and the comparative validity of specific biomarkers in identifying cognitive rumination. The review was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines on IEEE, Scopus, PubMed, and PsycInfo databases. Studies that used wearable devices to measure rumination-related physiological responses and biomarkers were included (n = 9); seven studies assessed one biomarker, and two studies assessed two biomarkers. Electrodermal Activity (EDA) sensors capturing skin conductance activity emerged as both the most prevalent sensor (n = 5) and the most comparatively valid biomarker for detecting cognitive rumination via wearable devices. Other commonly investigated biomarkers included electrical brain activity measured through Electroencephalogram (EEG) sensors (n = 2), Heart Rate Variability (HRV) measured using Electrocardiogram (ECG) sensors and heart rate fitness monitors (n = 2), muscle response measured through Electromyography (EMG) sensors (n = 1) and movement measured through an accelerometer (n = 1). The Empatica E4 and Empatica Embrace 2 wrist-worn devices were the most frequently used wearable (n = 3). The Rumination Response Scale (RRS), was the most widely used standard scale for assessing rumination. Experimental induction protocols, often adapted from Nolen-Hoeksema and Morrow's 1993 rumination induction paradigm, were also widely used. In conclusion, the findings suggest that wearable technology offers promise in capturing real-time physiological responses associated with rumination. However, the field is still developing, and further research is needed to validate these findings and explore the impact of individual traits and contextual factors on the accuracy of rumination detection.

Vertical Graphene-Based Multiparametric Sensing Array for Integration of Smart Catheter to Electrochemically Monitor Peritoneal Dialysis

Renal failure is typical chronic kidney disease that required peritoneal dialysis as the primary treatment, but current catheter devices lack functionality to monitor changes in chemical analytes during peritoneal dialysis. Fabrication of miniatured sensing modules with good electrochemical performance in tiny catheter devices is the key to realize the smart monitoring of peritoneal dialysis. In this work, a vertical graphene-based multiparametric sensing array (VG-MSA) is developed to continuously measure fluctuations of various analyte concentrations for peritoneal dialysis monitoring. Vertical graphene (VG) electrode with good electrochemical properties serves as the core module in VG-MSA, allowing the development of miniatured sensing modules with sufficient electrochemical performance. The VG-MSA enables sensitive and multiplexed measurement of dialysate components like metabolites (reactive oxygen species, uric acid, and glucose) and ions (K+, Ca2+, and H+). The VG-MSA is demonstrated to effectively detect biochemical signals in peritoneal dialysate in vivo on rat models. The VG-MSA catheter can be inserted into abdominal cavity, allowing full contact with dialysate for in situ, real-time, and continuous collection of biochemical information during peritoneal dialysis. The VG-MSA catheter device offers a valuable tool for monitoring dialysis quality and facilitating treatment adjustments, potentially as a promising platform for high-quality therapy of renal failure.

Multifunctional Porous Soft Bioelectronics

Soft bioelectronics, seamlessly interfacing with the human body to enable both recording and modulation of curvilinear biological tissues and organs, have significantly driven fields such as digital healthcare, human-machine interfaces, and robotics. Nonetheless, intractable challenges persist due to the onerous demand for imperceptible, burden-free, and user-centric comfortable bioelectronics. Porous soft bioelectronics is a new way to a library of imperceptible bioelectronic systems, that form natural interfaces with the human body. In this review, we provide an overview of the development and recent advances in multifunctional porous engineered soft bioelectronics, aiming to bridge the gap between living biotic and stiff abiotic systems. We first discuss strategies for fabricating porous, soft, and stretchable bioelectronic materials, emphasizing the concept of materials-level porous engineering for breathable and imperceptible bioelectronics. Next, we summarize wearable bioelectronics devices and multimodal systems with porous configurations designed for on-skin healthcare applications. Moving beneath the skin, we discuss implantable devices and systems enabled by porous bioelectronics with tissue-like compliance. Finally, existing challenges and translational gaps are also proposed to usher further research efforts towards realizing practical and clinical applications of porous bioelectronic systems; thus, revolutionizing conventional healthcare and medical practices and opening up unprecedented opportunities for long-term, imperceptible, non-invasive, and human-centric healthcare networks.

Easy-to-Engineer Flexible Nanoelectrode Sensor from an Inexpensive Overhead Projector Sheet for Sweat Neuropeptide-Y Detection

In this paper, we report an inexpensive and easy-to-engineer flexible nanobiosensor electrode platform by exploring a nonconductive overhead projector (OHP) sheet for sweat Neuropeptide-Y (NPY) detection, a potential biomarker for stress, cardiovascular regulation, appetite, etc. We converted a nonconductive OHP sheet into a conductive nanobiosensor electrode platform with a hybrid polymerization method, which consists of interfacial polymerization of pyrrole and a template-free electropolymerization technique to decorate the electrode platform with poly(EDOT-COOH-co-EDOT-EG3) nanotubes. The selection of poly(EDOT-COOH) features an easy conjugation of NPY antibody (NPY-Ab) through EDC/Sulfo-NHS coupling chemistry, while poly(EDOT-EG3) is best known to reduce nonspecific binding of biomolecules. The antibody conjugation on the polymer surface was characterized by a quartz crystal microbalance, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and chronoamperometry techniques. The OHP nanosensor platform exhibited the successful detection of NPY analyte through a chronoamperometry method in phosphate-buffered saline with a wide range of concentrations from 1 pg/mL to 1 μg/mL with a limit of detection of 0.68 pg/mL having good linearity (R2 = 0.9841). The sensor platform exhibited excellent stability, reproducibility, repeatability, and a shelf-life of 13 days. Furthermore, the sensor showed superior selectivity to a 100 pg/mL NPY analyte among other interfering compounds such as tumor necrosis factor α, cortisol, and Interleukin-6. The clinical practicality of the sensor was confirmed through the detection of 100 pg/mL NPY spiked artificial perspiration, highlighting the possibility of integrating the sensor platform to wearable healthcare applications.

Laser-Induced Graphene-Based Sensors in Health Monitoring: Progress, Sensing Mechanisms, and Applications

The rising global population and improved living standards have led to an alarming increase in non-communicable diseases, notably cardiovascular and chronic respiratory diseases, posing a severe threat to human health. Wearable sensing devices, utilizing micro-sensing technology for real-time monitoring, have emerged as promising tools for disease prevention. Among various sensing platforms, graphene-based sensors have shown exceptional performance in the field of micro-sensing. Laser-induced graphene (LIG) technology, a cost-effective and facile method for graphene preparation, has gained particular attention. By converting polymer films directly into patterned graphene materials at ambient temperature and pressure, LIG offers a convenient and environmentally friendly alternative to traditional methods, opening up innovative possibilities for electronic device fabrication. Integrating LIG-based sensors into health monitoring systems holds the potential to revolutionize health management. To commemorate the tenth anniversary of the discovery of LIG, this work provides a comprehensive overview of LIG's evolution and the progress of LIG-based sensors. Delving into the diverse sensing mechanisms of LIG-based sensors, recent research advances in the domain of health monitoring are explored. Furthermore, the opportunities and challenges associated with LIG-based sensors in health monitoring are briefly discussed.

A physiological perspective of the relevance of sweat biomarkers and their detection by wearable microfluidic technology: A review

The great majority of published microfluidic wearable platforms for sweat sensing focus on the development of the technology to fabricate the device, the integration of sensing materials and actuators and the fluidics of sweat within the device. However, very few papers have discussed the physiological relevance of the metabolites measured using these novel approaches. In fact, some of the analytes present in sweat, which serve as biomarkers in blood, do not show a correlation with blood levels. This discrepancy can be attributed to factors such as contamination during measurements, the metabolism of sweat glands, or challenges in obtaining significant samples. The objective of this review is to present a critical and meaningful insight into the real applicability and potential use of wearable technology for improving health and sport performance. It also discusses the current limitations and future challenges of microfluidics, aiming to provide accurate information about the actual needs in this field. This work is expected to contribute to the future development of more suitable wearable microfluidic technology for health and sports science monitoring, using sweat as the biofluid for analysis.

Alzheimer's diagnosis beyond cerebrospinal fluid: Probe-Free Detection of Tau Proteins using MXene based redox systems and molecularly imprinted polymers

Phosphorylated Tau proteins are promising biomarkers for the diagnosis and prognosis of Alzheimer's disease. This study presents a novel voltametric sensor using a vanadium MXene polydopamine (VxPDA) redox active composite and a Tau-441-specific polyaniline molecularly imprinted polymer (PANI MIP) for the sensitive detection of Tau-441 in interstitial fluid (ISF) and plasma. The VxPDA/PANI MIP sensor demonstrates a broad detection range of 5 fg/mL to 5 ng/mL (122 aM/L to 122 pM/L) in ISF without the use of redox mediators, with a lower limit of detection (LOD) of 2.3 fg/mL (60 aM/L). Furthermore, a handheld device utilizing this technology successfully detects Tau-441 in artificial serum with high sensitivity (5 fg/mL to 150 fg/mL (122 aM/L to 366 aM/L)) and specificity within a clinically relevant range. The rapid detection time (∼32 min) and low cost (∼£20/device) of this sensor highlight its potential for minimally invasive, early AD diagnosis in clinical settings. This advancement aims to facilitate a transition away from invasive cerebrospinal fluid (CSF)-based diagnostic techniques for AD.

Multiscale crack trapping for programmable adhesives

The precise control of crack propagation at bonded interfaces is crucial for smart adhesives with advanced performance. However, previous studies have primarily concentrated on either microscale or macroscale crack propagation. Here, we present a hybrid adhesive that integrates microarchitectures and macroscopic nonlinear cut architectures for unparalleled adhesion control. The integration of these architectural elements enables conformal attachment and simultaneous crack trapping across multiple scales for high capacity, enhancing adhesion by more than 70×, while facilitating crack propagation at the macroscale in specific directions for programmable release and reusability. As adhesion strength and directionality can be independently controlled at any location, skin adhesive patches are created that are breathable, nondamaging, and exceptionally strong and secure yet remove easily. These capabilities are demonstrated with a skin-mounted adhesive patch with integrated electronics that accurately detects human motion and wirelessly transmits signals, enabling real-time control of avatars in virtual reality applications.

Cortisol: Biosensing and detection strategies

Cortisol, a crucial steroid hormone synthesized by the adrenal glands, has diverse impacts on multiple physiological processes, such as metabolism, immune function, and stress management. Disruption in cortisol levels can result in conditions like Cushing's syndrome and Addison's disease. This review provides an in-depth exploration of cortisol, covering its structure, various forms in the body, detection methodologies, and emerging trends in cancer treatment and detection. Various techniques for cortisol detection, including electrochemical, chromatographic, and immunoassay methods were discussed and highlighted for their merits and applications. Electrochemical immunosensing emerges as a promising approach, which offered high sensitivity and low detection limits. Moreover, the review delves into the intricate relationship between cortisol and cancer, emphasizing cortisol's role in cancer progression and treatment outcomes. Lastly, the utilization of biomarkers, in-silico modeling, and machine learning for electrochemical cortisol detection were explored, which showcased innovative strategies for stress monitoring and healthcare advancement.

Recent Progress in Wearable Near-Sensor and In-Sensor Intelligent Perception Systems

As the Internet of Things (IoT) becomes more widespread, wearable smart systems will begin to be used in a variety of applications in people's daily lives, not only requiring the devices to have excellent flexibility and biocompatibility, but also taking into account redundant data and communication delays due to the use of a large number of sensors. Fortunately, the emerging paradigms of near-sensor and in-sensor computing, together with the proposal of flexible neuromorphic devices, provides a viable solution for the application of intelligent low-power wearable devices. Therefore, wearable smart systems based on new computing paradigms are of great research value. This review discusses the research status of a flexible five-sense sensing system based on near-sensor and in-sensor architectures, considering material design, structural design and circuit design. Furthermore, we summarize challenging problems that need to be solved and provide an outlook on the potential applications of intelligent wearable devices.

Memristor-Based Artificial Chips

Memristors, promising nanoelectronic devices with in-memory resistive switching behavior that is assembled with a physically integrated core processing unit (CPU) and memory unit and even possesses highly possible multistate electrical behavior, could avoid the von Neumann bottleneck of traditional computing devices and show a highly efficient ability of parallel computation and high information storage. These advantages position them as potential candidates for future data-centric computing requirements and add remarkable vigor to the research of next-generation artificial intelligence (AI) systems, particularly those that involve brain-like intelligence applications. This work provides an overview of the evolution of memristor-based devices, from their initial use in creating artificial synapses and neural networks to their application in developing advanced AI systems and brain-like chips. It offers a broad perspective of the key device primitives enabling their special applications from the view of materials, nanostructure, and mechanism models. We highlight these demonstrations of memristor-based nanoelectronic devices that have potential for use in the field of brain-like AI, point out the existing challenges of memristor-based nanodevices toward brain-like chips, and propose the guiding principle and promising outlook for future device promotion and system optimization in the biomedical AI field.

Beyond Tissue replacement: The Emerging role of smart implants in healthcare

Smart implants are increasingly used to treat various diseases, track patient status, and restore tissue and organ function. These devices support internal organs, actively stimulate nerves, and monitor essential functions. With continuous monitoring or stimulation, patient observation quality and subsequent treatment can be improved. Additionally, using biodegradable and entirely excreted implant materials eliminates the need for surgical removal, providing a patient-friendly solution. In this review, we classify smart implants and discuss the latest prototypes, materials, and technologies employed in their creation. Our focus lies in exploring medical devices beyond replacing an organ or tissue and incorporating new functionality through sensors and electronic circuits. We also examine the advantages, opportunities, and challenges of creating implantable devices that preserve all critical functions. By presenting an in-depth overview of the current state-of-the-art smart implants, we shed light on persistent issues and limitations while discussing potential avenues for future advancements in materials used for these devices.

Effect of Probiotic Therapy on Neuropsychiatric Manifestations in Children with Multiple Neurotransmitter Disorders: A Study

Probiotics, also known as psychobiotics, have been linked to cognitive functions, memory, learning, and behavior, in addition to their positive effects on the digestive tract. The purpose of this study is to examine the psychoemotional effects and cognitive functioning in children with gastrointestinal disorders who undergo psychobiotherapy. A total of 135 participants, aged 5-18 years, were divided into three groups based on the pediatrician's diagnosis: Group I (Control) consisted of 37 patients (27.4%), Group II included 65 patients (48.1%) with psychoanxiety disorders, and Group III comprised 33 individuals (24.4%) with psychiatric disorders. The study monitored neurotransmitter levels such as serotonin, GABA, glutamate, cortisol, and DHEA, as well as neuropsychiatric symptoms including headaches, fatigue, mood swings, hyperactivity, aggressiveness, sleep disorders, and lack of concentration in patients who had gastrointestinal issues such as constipation, diarrhea, and other gastrointestinal problems. The results indicate that psychobiotics have a significant impact on reducing hyperactivity and aggression, and improving concentration. While further extensive studies are needed, these findings offer promising insights into the complexity of a child's neuropsychic behavior and the potential for balancing certain behaviors through psychobiotics.

Implantable microfluidics: methods and applications

Implantable microfluidics involves integrating microfluidic functionalities into implantable devices, such as medical implants or bioelectronic devices, revolutionizing healthcare by enabling personalized and precise diagnostics, targeted drug delivery, and regeneration of targeted tissues or organs. The impact of implantable microfluidics depends heavily on advancements in both methods and applications. Despite significant progress in the past two decades, continuous advancements are still required in fluidic control and manipulation, device miniaturization and integration, biosafety considerations, as well as the development of various application scenarios to address a wide range of healthcare issues. In this review, we discuss advancements in implantable microfluidics, focusing on methods and applications. Regarding methods, we discuss progress made in fluid manipulation, device fabrication, and biosafety considerations in implantable microfluidics. In terms of applications, we review advancements in using implantable microfluidics for drug delivery, diagnostics, tissue engineering, and energy harvesting. The purpose of this review is to expand research ideas for the development of novel implantable microfluidic devices for various healthcare applications.

Oriented Antibody-Assembled Metal-Organic Frameworks for Persistent Wearable Sweat Cortisol Detection

The level of cortisol can reflect people's psychological stress, help diagnose adrenal gland diseases, and is also related to several mental diseases. In this study, we developed a cortisol monoclonal antibody-oriented approach to modify an immunosensor for wearable label-free and persistent sweat cortisol detection. On such an antibody-oriented immunosensor, the fragment crystallizable (Fc) region is partially inserted within the metal-organic framework (MOF), and antibody-binding regions of the cortisol monoclonal antibody (Cmab) were exposed on the MOF surface via selective growth and self-assembly. Such ordered and oriented embedding of antibodies in the MOF resulted in excellent antibody activity and improved stability and antigen-binding capacity. We also engineered the full integrated system for on-body sweat cortisol biosensing performance in several volunteers, and the results indicated that this wearable sensor is suitable for practical cortisol detection with a good linear detection range from 1 pg/mL to 1 μg/mL with a lower limit of detection of 0.26 pg/mL. Moreover, the wearable sensor demonstrated good persistence in detecting cortisol, with only 4.1% decay after 9 days of storage. The present work represents a simple oriented antibody assembling approach to improve the stability of antibodies, providing an important step toward long-term continuous sweat biomarker detection.