Soft, smart contact lenses with integrations of wireless circuits, glucose sensors, and displays

Tear-Based Battery Embedded with Prussian Blue Analogues and Silver Nanoparticles for Smart Contact Lenses

Smart contact lenses coupled with electronic components have vast potential for healthcare applications, as such advanced technology enables continuous and noninvasive monitoring of vital signs and disease diagnosis. However, stringent safety and nontoxicity requirements for ocular devices restrict the applications of flexible batteries fabricated by conventional methods. Here, we design a safe and flexible tear-based aqueous battery composed of Prussian blue analogues and silver nanoparticle films for cathode and anode, respectively. The battery exhibited satisfying cyclic electrochemical performance, with a discharge capacity of 195.37 μAh in a tear-like solution with interferences at 34.5 °C within the voltage ranges from 0.2 to 1.0 V. The power and voltage were sufficient to enable a temperature sensor. In addition, the rate capability, mechanical stability, and biocompatibility of the battery have been demonstrated as well.

Electrochemically Active Materials for Tissue-Interfaced Soft Biochemical Sensing

Tissue-interfaced soft biochemical sensing represents a crucial approach to personalized healthcare by employing electrochemically active materials to monitor biochemical signals at the tissue interface in real time, either noninvasively or through implantation. These soft biochemical sensors can be integrated with various biological tissues, such as neural, gastrointestinal, ocular, cardiac, skin, muscle, and bone, adapting to their unique mechanical and biochemical environments. Sensors employing materials like conductive polymers, composites, metals, metal oxides, and carbon-based nanomaterials have demonstrated capabilities in applications, such as continuous glucose monitoring, neural activity mapping, and real-time metabolite detection, enhancing diagnostics and treatment monitoring across a range of medical fields. Next-generation tissue-interfaced biosensors that enable multimodal and multiplexed measurement of biochemical markers and physiological parameters could be transformative for personalized medicine, allowing for high-resolution, time-resolved historical monitoring of an individual's health status. In this review, we summarize current trends in the field to provide insights into the challenges and future trajectory of tissue-interfaced soft biochemical sensors, highlighting their potential to revolutionize personalized medicine and improve patient outcomes.

Low-Temperature Single-Step Inkjet-Printed Metallic Patterns With Self-Regulated Vertical Compositional Gradient

For the rapidly growing demands and expanding range of applications of printed electronics in medicine lower processing temperatures and simpler steps are preferred to minimize the fabrication processes onto a range of substrates. Various hybrid inks are formulated for fabricating multi-compositional functional patterns with fewer manufacturing processes. However, most hybrid inks can only form patterns with fully-mixed compositional distribution. This study proposes a novel hybrid metal-based ink formulation pathway and develops a particle-free Ag-Cu hybrid metal-organic decomposition (MOD) ink. When sintering under N2 the in situ formed Ag and Cu nano-particulates during the sintering process self-regulate into a unique vertical compositional gradient with Cu dominant on top and the majority of Ag existing beneath. Highly conductive (1.88 ± 0.7 × 106 S m-1) metallic patterns are fabricated by single-step inkjet printing at low temperature (<150 °C) on both rigid and cellulose fiber substrates. When sintered under air a porous CuO layer is generated on the surface with high electrocatalytic activity with glucose (stable for over 2 h of continuous measurement). This work shows the feasibility of fabricating a glucose sensor including electrode layer and functional layer by single-step printing.

Wearable Electrochemical Glucose Sensors for Fluid Monitoring: Advances and Challenges in Non-Invasive and Minimally Invasive Technologies

This review highlights the latest developments in wearable electrochemical glucose sensors, focusing on their transition from invasive to non-invasive and minimally invasive designs. We discuss the underlying mechanisms, performance metrics, and practical challenges of these technologies, emphasizing their potential to revolutionize diabetes care. Additionally, we explore the motivation behind this review: to provide a comprehensive analysis of emerging sensing platforms, assess their clinical applicability, and identify key research gaps that need addressing to achieve reliable, long-term glucose monitoring. By evaluating electrochemical sensors based on tears, saliva, sweat, urine, and interstitial fluid, this work aims to guide future innovations toward more accessible, accurate, and user-friendly solutions for diabetic patients, ultimately improving their quality of life and disease management outcomes.

From population-based to personalized laboratory medicine: continuous monitoring of individual laboratory data with wearable biosensors

Monitoring individuals' laboratory data is essential for assessing their health status, evaluating the effectiveness of treatments, predicting disease prognosis and detecting subclinical conditions. Currently, monitoring is performed intermittently, measuring serum, plasma, whole blood, urine and occasionally other body fluids at predefined time intervals. The ideal monitoring approach entails continuous measurement of concentration and activity of biomolecules in all body fluids, including solid tissues. This can be achieved through the use of biosensors strategically placed at various locations on the human body where measurements are required for monitoring. High-tech wearable biosensors provide an ideal, noninvasive, and esthetically pleasing solution for monitoring individuals' laboratory data. However, despite significant advances in wearable biosensor technology, the measurement capacities and the number of different analytes that are continuously monitored in patients are not yet at the desired level. In this review, we conducted a literature search and examined: (i) an overview of the background of monitoring for personalized laboratory medicine, (ii) the body fluids and analytes used for monitoring individuals, (iii) the different types of biosensors and methods used for measuring the concentration and activity of biomolecules, and (iv) the statistical algorithms used for personalized data analysis and interpretation in monitoring and evaluation.

Implantable bioelectronics and wearable sensors for kidney health and disease

Established clinical practices for monitoring kidney health and disease - including biopsy and serum biomarker analysis - suffer from practical limitations in monitoring frequency and lack adequate sensitivity for early disease detection. Engineering advances in biosensors have led to the development of wearable and implantable systems for monitoring of kidney health. Non-invasive microfluidic systems have demonstrated utility in the detection of kidney-relevant biomarkers, such as creatinine, urea and electrolytes in peripheral body fluids such as sweat, interstitial fluid, tears and saliva. Implantable systems may aid the identification of early transplant rejection through analysis of organ temperature and perfusion, and enable real-time assessment of inflammation through the use of thermal sensors. These technologies enable continuous, real-time monitoring of kidney health, offering complementary information to standard clinical procedures to alert physicians of changes in kidney health for early intervention. In this Review, we explore devices for monitoring renal biomarkers in peripheral biofluids and discuss developments in implantable sensors for the direct measurement of the local, biophysical properties of kidney tissue. We also describe potential clinical applications, including monitoring of chronic kidney disease, acute kidney injury and allograft health.

Plasmonic smart contact lens based on etalon nanostructure for tear glucose sensing

Smart contact lenses, one of the most advanced wearable platforms, offer a combination of optical and electronic technologies that provide exceptional capabilities in various fields. These lenses are equipped with biosensors, microchips, and sometimes even miniature displays that enable the collection and analysis of biological and environmental data. Smart contact lenses represent a big leap in wearable technology and biosensors, potentially providing a new future for human interaction with the digital world, improving personal health, and promising a hopeful future in vision and wearable technologies. In this study, smart contact lenses based on plasmonic etalon nanostructure have been proposed and fabricated for tear glucose sensing. A cost-effective and simple technique of soft nanolithography has been proposed to fabricate a plasmonic sensor chip on a contact lens, enabling the detection of glucose solutions at different concentrations of 0.15, 1.5, 5, and 10 mM in a phosphate-buffered saline (PBS) solution. The proposed plasmonic etalon-based smart contact lens as a wearable platform exhibits the capacity to sense tear glucose (even at low concentration values) and offers relatively high sensitivity for non-invasive tear glucose sensing applications. The biocompatibility, cost-effectiveness, stability, and simple production of these contact lenses may provide new perspectives on wearable biosensors.

Enhancing glaucoma care with smart contact lenses: An overview of recent developments

Glaucoma is a leading cause of irreversible blindness worldwide, affecting millions of individuals due to its progressive damage to the optic nerve, often caused by elevated intraocular pressure (IOP). Conventional methods of IOP monitoring, such as tonometry, provide sporadic and often inaccurate readings due to fluctuations throughout the day, leaving significant gaps in diagnosis and treatment. This review explores the transformative potential of smart contact lenses equipped with continuous IOP monitoring and therapeutic capabilities. These lenses integrate advanced materials such as graphene, nanogels, and magnetic oxide nanosheets alongside sophisticated biosensing and wireless communication systems. By offering continuous, real-time data, these lenses can detect subtle IOP fluctuations and provide immediate feedback to patients and clinicians. Moreover, drug-eluting capabilities embedded in these lenses present a groundbreaking approach to glaucoma therapy by improving medication adherence and providing controlled drug release directly to the eye. Beyond IOP management, these innovations also pave the way for monitoring biochemical markers and other ocular diseases. Challenges such as biocompatibility, long-term wearability, and affordability remain, but the integration of cutting-edge technologies in smart contact lenses signifies a paradigm shift in glaucoma care. These developments hold immense promise for advancing personalized medicine, improving patient outcomes, and mitigating the global burden of blindness.

Graphene-Based Glucose Sensors with an Attomolar Limit of Detection

Diabetes mellitus, a prevalent metabolic disorder affecting hundreds of millions of people worldwide, demands continuous glucose monitoring for effective management. Current blood glucose monitoring methods, such as commercial glucometers, are accurate but are often perceived as uncomfortable. Motivated by the need for noninvasive, ultrasensitive alternatives, our study presents electrolyte-gated graphene field-effect transistors functionalized with glucose oxidase. We developed an optimized fabrication process that integrates a 32-transistor matrix within a miniaturized 1000 μm2 footprint, ensuring high device uniformity while enabling detection in 40 μL analyte volume. A comprehensive suite of techniques─including Raman spectroscopy, X-ray photoelectron spectroscopy, and water contact angle measurements─reveals the stepwise evolution of graphene chemistry and surface properties leading to the controlled immobilization of glucose oxidase. Our findings demonstrate p-type doping and tensile strain in the graphene channel across the nanomolar-millimolar glucose concentration range. The enzyme-catalyzed oxidation of glucose produces hydrogen peroxide in close proximity to the graphene channel, inducing a systematic shift in the Dirac point voltage toward more positive values. Under these conditions, the biosensor achieves an attomolar limit of detection and a sensitivity of 10.6 mV/decade, outperforming previously reported glucose sensors. Selectivity tests against common interferents such as lactate and ascorbic acid, as well as validation in artificial and human tears, demonstrate its robustness for real-world applications. Altogether, these findings position the electrolyte-gated graphene field-effect transistor as a transformative, noninvasive glucose-sensing platform, paving the way for next-generation continuous monitoring devices, including wearable formats for real-time, user-friendly diabetes management.

Photo-crosslinkable organic materials for flexible and stretchable electronics

As technology advances to enhance human perceptual experiences of the surrounding environment, significant research on stretchable electronics is actively progressing, spanning from the synthesis of materials to their applications in fully integrated devices. A critical challenge lies in developing materials that can maintain their electrical properties under substantial stretching. Photo-crosslinkable organic materials have emerged as a promising solution due to their ability to be precisely modified with light to achieve desired properties, such as enhanced durability, stable conductivity, and micropatterning. This review examines recent research on photo-crosslinkable organic materials, focusing on their components and integration within stretchable electronic devices. We explore the essential characteristics required for each device component (insulators, semiconductors, and conductors) and explain how photo-crosslinking technology addresses these needs through its principles and implementation. Additionally, we discuss the integration and utilization of these components in real-world applications, including physical sensors, organic field-effect transistors (OFETs), and organic solar cells (OSCs). Finally, we offer a concise perspective on the future directions and potential challenges in ongoing research on photo-crosslinkable organic materials.

Microfluidic contact lens: fabrication approaches and applications

Microfluidic contact lenses integrate microscale features that can efficiently and precisely manipulate, interact, and analyze the small volumes of tears available in the limited accessible space for the lens in the eye. The microfluidic network on contact lenses allows the miniaturization of biochemical operations on the wealth of physiological information available in the eye. Sensors integrated into channels enable real-time monitoring of ocular parameters, including glucose, pH, electrolytes, or other biomarkers. Additionally, microchannel-integrated contact lenses have demonstrated potential as power-free, continuous intraocular pressure monitoring platforms for the effective management of glaucoma. Furthermore, the controlled release of medications directly onto the eye from microfluidic contact lenses enhances therapeutic efficacy by increasing bioavailability. Despite current challenges such as scalable fabrication techniques, microfluidic contact lenses hold immense promise for ocular health, bridging the gap between diagnostics and treatment. This review summarizes the progress made in the design and fabrication of microfluidic contact lenses, with a special emphasis on the methods adopted to fabricate microfluidic contact lenses. Furthermore, the various applications of microfluidic contact lenses, ocular disease diagnosis, and drug delivery in particular are discussed in detail. Aside from outlining the state-of-the-art research activities in this area, challenges and future directions are discussed here.

A review on electrode materials of supercapacitors used in wearable bioelectronics and implantable biomedical applications

Supercapacitors, a class of electrochemical energy storage devices, offer a promising solution for powering wearable bioelectronics and implantable biomedical devices. Their high-power density, rapid charge-discharge capabilities, and long cycle life make them ideal for applications requiring quick bursts of energy and extended operation. To address the challenges of energy density, self-discharge, miniaturization, integration, and power consumption, researchers are exploring various strategies, including developing novel electrode materials, optimizing device architectures, and integrating advanced fabrication techniques. Metal oxides, carbon-based materials, MXenes, and their composites have emerged as promising electrode materials due to their high specific surface area, excellent conductivity, and biocompatibility. For wearable bioelectronics, supercapacitors can power a wide range of devices, including wearable sensors, smart textiles, and other devices that require intermittent or pulsed energy. In implantable biomedical devices, supercapacitors offer a reliable and safe power source for applications such as pacemakers, neural implants, and drug delivery systems. By addressing the challenges and capitalizing on emerging technologies, supercapacitors have the potential to revolutionize the field of bioelectronics and biomedical engineering, enabling the development of innovative devices that improve healthcare and quality of life.

Functional design of metal aerogels for wearable electrochemical biosensing devices

Metal aerogels (MAs) represent a novel class of aerogels composed entirely of interconnected metal nanoparticles or nanostructures. They integrate the unique physicochemical properties of metals with the high surface area and porosity of traditional aerogels, resulting in high electrochemical activity, efficient mass and electron transport, and considerable mechanical stability. These attributes make MAs particularly appealing for applications in wearable electrochemical biosensing devices. As electrode materials for electrochemical sensors, MAs can serve as carriers for enzymes or as electrocatalysts (with inherent electrocatalytic properties), thereby delivering superior sensing performance. Moreover, their three-dimensional, interconnected network structure imparts inherent flexibility, making them highly suitable for wearable biosensor electrodes. This review highlights recent advancements in the functional design of MAs for wearable electrochemical sensors and evaluates their performance in human biomarker monitoring. It also explores the challenges and future potential of MAs in such wearable devices. With ongoing progress in materials science, MA-based wearable biosensors hold significant promise for advancing disease diagnosis and health management.

Smart theranostic contact lenses

Although smart contact lenses have demonstrated great potential in theranostics, there remain critical challenges and opportunities in their commercial development. In this Perspective, the current status and capability of smart theranostic contact lenses are highlighted, focusing on their application as sensing systems for detecting biomarkers such as glucose, intraocular pressure (IOP), and inflammatory cytokines, and as drug delivery systems (DDS) for precise and controlled therapy. Additionally, key challenges associated with clinical development and commercialization of smart theranostic contact lenses are discussed, to optimize diagnostic and therapeutic interventions. Considering the rapid evolution of the field, we finally also discuss the need for systematic studies on safety, efficacy, and mass-production, and we spark new ideas for advancing smart theranostic contact lenses into versatile platforms for personalized medicine.

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.

Trends and Advances in Wearable Plasmonic Sensors Utilizing Surface-Enhanced Raman Spectroscopy (SERS): A Comprehensive Review

Wearable sensors have appeared as a promising solution for real-time, non-invasive monitoring in diverse fields, including healthcare, environmental sensing, and wearable electronics. Surface-enhanced Raman spectroscopy (SERS)-based sensors leverage the unique properties of SERS, such as plasmonic signal enhancement, high molecular specificity, and the potential for single-molecule detection, to detect and identify a wide range of analytes with ultra-high sensitivity and molecular selectivity. However, it is important to note that wearable sensors utilize various sensing mechanisms, and not all rely on SERS technology, as their design depends on the specific application. This comprehensive review highlights the recent trends and advancements in wearable plasmonic sensing technologies, focusing on their design, fabrication, and integration into practical wearable devices. Key innovations in material selection, such as the use of nanomaterials and flexible substrates, have significantly enhanced sensor performance and wearability. Moreover, we discuss challenges such as miniaturization, power consumption, and long-term stability, along with potential solutions to address these issues. Finally, the outlook for wearable plasmonic sensing technologies is presented, emphasizing the need for interdisciplinary research to drive the next generation of smart wearables capable of real-time health diagnostics, environmental monitoring, and beyond.

Biointerface engineering of flexible and wearable electronics

Biointerface sensing is a cutting-edge interdisciplinary field that merges conceptual and practical aspects. Wearable bioelectronics enable efficient interaction and close contact with biological components such as tissues and organs, paving the way for a wide range of medical applications, including personal health monitoring and medical intervention. To be applicable in real-world settings, the patches must be stable and adhere to the skin without causing discomfort or allergies in both wet and dry conditions, as well as other desirable features such as being ultra-soft, thin, flexible, and stretchable. Biosensors have emerged as promising tools primarily used to directly detect biological and electrophysiological signals, enhancing the efficacy of personalized medical treatments and enabling accurate tracking of human well-being. This review highlights the engineering of skin-tissue surfaces/interfaces and their interactions with wearable patches, aiming for both a broad and in-depth understanding of the mechanical and physicochemical properties required for the advancement of flexible and wearable skin patches. Specifically, the advantages of flexible bioelectronics and sensors with optimized surface geometry for long-term diagnosis are discussed. This insight aims to guide the future development of functional materials that can interact with human tissue in a controlled manner. Finally, we provide perspectives on the challenges and potential applications of biointerface engineering in wearable devices.

Photonic Nanomaterials for Wearable Health Solutions

This review underscores the transformative potential of photonic nanomaterials in wearable health technologies, driven by increasing demands for personalized health monitoring. Their unique optical and physical properties enable rapid, precise, and sensitive real-time monitoring, outperforming conventional electrical-based sensors. Integrated into ultra-thin, flexible, and stretchable formats, these materials enhance compatibility with the human body, enabling prolonged wear, improved efficiency, and reduced power consumption. A comprehensive exploration is provided of the integration of photonic nanomaterials into wearable devices, addressing material selection, light-matter interaction principles, and device assembly strategies. The review highlights critical elements such as device form factors, sensing modalities, and power and data communication, with representative examples in skin patches and contact lenses. These devices enable precise monitoring and management of biomarkers of diseases or biological responses. Furthermore, advancements in materials and integration approaches have paved the way for continuum of care systems combining multifunctional sensors with therapeutic drug delivery mechanisms. To overcome existing barriers, this review outlines strategies of material design, device engineering, system integration, and machine learning to inspire innovation and accelerate the adoption of photonic nanomaterials for next-generation of wearable health, showcasing their versatility and transformative potential for digital health applications.

Vialess heterogeneous skin patch for multimodal monitoring and stimulation

System-level wearable electronics require to be flexible to ensure conformal contact with the skin, but they also need to integrate rigid and bulky functional components to achieve system-level functionality. As one of integration methods, folding integration offers simplified processing and enhanced functionality through rigid-soft region separation, but so far, it has mainly been applied to modality of electrical sensing and stimulation. This paper introduces a vialess heterogeneous skin patch with multi modalities that separates the soft region and strain-robust region through folded structure. Our system includes electrical and optical modalities for hemodynamic and cardiovascular monitoring, and a force-electrically driven micropump for drug delivery. Each modality is demonstrated through on-demand drug delivery, flexible waveguide-based PPG monitoring, and ECG and body movement monitoring. Wireless data transmission and real-time measurement validate the feedback operation for multi-modalities. This engineered closed-loop platform offers the possibility for broad applications, including cardiovascular monitoring and chronic disease management.

A bibliometric and visualization analysis of electrochemical biosensors for early diagnosis of eye diseases

Electrochemical biosensors can provide an economical, accurate and rapid method for early screening of disease biomarkers in clinical medicine due to their high sensitivity, selectivity, portability, low cost and easy manufacturing, and multiplexing capability. Tear, a fluid naturally secreted by the human body, is not only easily accessible but also contains a great deal of biological information. However, no bibliometric studies focus on applying electrochemical sensors in tear/eye diseases. Therefore, we utilized VOSviewer and CiteSpace, to perform a detailed bibliometric analysis of 114 papers in the field of research on the application of tear in electrochemical biosensors screened from Web of Science with the combination of Scimago Graphica and Microsoft Excel for visualization to show the current research hotspots and future trends. The results show that the research in this field started in 2008 and experienced an emerging period in recent years. Researchers from China and the United States mainly contributed to the thriving research areas, with 41 and 29 articles published, respectively. Joseph Wang from the University of California San Diego is the most influential author in the field, and Biosensors & Bioelectronics is the journal with the most published research and the most cited journal. The highest appearance keywords were "biosensor" and "tear glucose," while the most recent booming keywords "diagnosis" and "in-vivo" were. In conclusion, this study elucidates current trends, hotspots, and emerging frontiers, and provides future biomarkers of ocular and systemic diseases by electrochemical sensors in tear with new ideas and opinions.

Advancements in Passive Wireless Sensing Systems in Monitoring Harsh Environment and Healthcare Applications

Recent advancements in passive wireless sensor technology have significantly extended the application scope of sensing, particularly in challenging environments for monitoring industry and healthcare applications. These systems are equipped with battery-free operation, wireless connectivity, and are designed to be both miniaturized and lightweight. Such features enable the safe, real-time monitoring of industrial environments and support high-precision physiological measurements in confined internal body spaces and on wearable epidermal devices. Despite the exploration into diverse application environments, the development of a systematic and comprehensive research framework for system architecture remains elusive, which hampers further optimization of these systems. This review, therefore, begins with an examination of application scenarios, progresses to evaluate current system architectures, and discusses the function of each component-specifically, the passive sensor module, the wireless communication model, and the readout module-within the context of key implementations in target sensing systems. Furthermore, we present case studies that demonstrate the feasibility of proposed classified components for sensing scenarios, derived from this systematic approach. By outlining a research trajectory for the application of passive wireless systems in sensing technologies, this paper aims to establish a foundation for more advanced, user-friendly applications.

Ultrathin, Lightweight Materials Enabled Wireless Data and Power Transmission in Chip-Less Flexible Electronics

The surge of flexible, biointegrated electronics has inspired continued research efforts in designing and developing chip-less and wireless devices as soft and mechanically compliant interfaces to the living systems. In recent years, innovations in materials, devices, and systems have been reported to address challenges surrounding this topic to empower their reliable operation for monitoring physiological signals. This perspective provides a brief overview of recent works reporting various chip-less electronics for sensing and actuation in diverse application scenarios. We summarize wireless signal/data/power transmission strategies, key considerations in materials design and selection, as well as successful demonstrations of sensors and actuators in wearable and implantable forms. The final section provides an outlook to the future direction down the road for performance improvement and optimization. These versatile, inexpensive, and low-power device concepts can serve as alternative strategies to existing digital wireless electronics, which will find broad applications as bidirectional biointerfaces in basic biomedical research and clinical practices.

Wearable Electrochemical Biosensors for Advanced Healthcare Monitoring

Recent advancements in wearable electrochemical biosensors have opened new avenues for on-body and continuous detection of biomarkers, enabling personalized, real-time, and preventive healthcare. While glucose monitoring has set a precedent for wearable biosensors, the field is rapidly expanding to include a wider range of analytes crucial for disease diagnosis, treatment, and management. In this review, recent key innovations are examined in the design and manufacturing underpinning these biosensing platforms including biorecognition elements, signal transduction methods, electrode and substrate materials, and fabrication techniques. The applications of these biosensors are then highlighted in detecting a variety of biochemical markers, such as small molecules, hormones, drugs, and macromolecules, in biofluids including interstitial fluid, sweat, wound exudate, saliva, and tears. Additionally, the review also covers recent advances in wearable electrochemical biosensing platforms, such as multi-sensory integration, closed-loop control, and power supply. Furthermore, the challenges associated with critical issues are discussed, such as biocompatibility, biofouling, and sensor degradation, and the opportunities in materials science, nanotechnology, and artificial intelligence to overcome these limitations.

Customized surface adhesive and wettability properties of conformal electronic devices

Conformal and body-adaptive electronics have revolutionized the way we interact with technology, ushering in a new era of wearable devices that can seamlessly integrate with our daily lives. However, the inherent mismatch between artificially synthesized materials and biological tissues (caused by irregular skin fold, skin hair, sweat, and skin grease) needs to be addressed, which can be realized using body-adaptive electronics by rational design of their surface adhesive and wettability properties. Over the past few decades, various approaches have been developed to enhance the conformability and adaptability of bioelectronics by (i) increasing flexibility and reducing device thickness, (ii) improving the adhesion and wettability between bioelectronics and biological interfaces, and (iii) refining the integration process with biological systems. Successful development of a conformal and body-adaptive electronic device requires comprehensive consideration of all three aspects. This review starts with the design strategies of conformal electronics with different surface adhesive and wettability properties. A series of conformal and body-adaptive electronics used in the human body under both dry and wet conditions are systematically discussed. Finally, the current challenges and critical perspectives are summarized, focusing on promising directions such as telemedicine, mobile health, point-of-care diagnostics, and human-machine interface applications.

Application of non-dominated sorting genetic algorithm (NSGA-III) and radial basis function (RBF) interpolation for mitigating node displacement in smart contact lenses

With the rapid development of wearable technology, smart contact lenses (SCL) are gradually gaining attention as a breakthrough innovation. The emergence of these products suggests that smart glasses, which incorporate electronic components and visual aids, are expected to become the mainstream of human-computer interaction in the future. However, realizing this vision requires not only advanced electronics but also highly sophisticated manufacturing processes. Therefore, this paper provides an in-depth discussion on the process of manufacturing smart contact lenses using in-mold electronic decoration technology and focuses on the multi-objective problem of optimizing injection parameters such as melt temperature and holding pressure to achieve on micro-molecular displacements as well as residual stresses. First, the background and technical requirements of smart contact lenses are described in detail, emphasizing the prospect of SCL for a wide range of applications in augmented reality, healthcare, and smart assistance. Subsequently, the key role of IME technology in SCL manufacturing is discussed. Focusing on the optimization of melting temperature, holding pressure and holding time, the effects of these three key parameters on eyewear were systematically analyzed with the goal of improving the overall performance and biocompatibility of SCL. The multi-objective optimization of melting temperature and holding pressure was achieved by NSGA-III. Radial basis function interpolation was used as an auxiliary method to provide finer optimization results for NSGA-III. During the multi-objective optimization process, efforts were made to achieve uniform flow of melt temperature and optimal adjustment of holding pressure to maximize the transparency, stability and comfort of SCL. The final results obtained achieved an optimization rate of 95.60% and 93.47% for nodal displacement and residual stress, respectively, compared with the initially recommended process parameters.

Insertable Biomaterial-Based Multianalyte Barcode Sensor toward Continuous Monitoring of Glucose and Oxygen

Chronic diseases, including diabetes, cardiovascular diseases, and microvascular complications, contribute significantly to global morbidity and mortality. Current monitoring tools such as glucometers and continuous glucose monitors only measure one analyte; multiplexing technologies offer a promising approach for monitoring multiple biomarkers, enabling the management of comorbidities and providing more comprehensive disease insights. In this work, we describe a miniaturized optical "barcode" sensor with high biocompatibility for the continuous monitoring of glucose and oxygen. This enzymatic sensor relies on oxygen consumption in proportion to local glucose levels and the phosphorescence reporting of tissue oxygen with a lifetime-based probe. The sensor was specifically designed to operate in a tissue environment with low levels of dissolved oxygen. The barcode sensor consists of a poly(ethylene glycol) diacrylate (PEGDA) hydrogel with four discrete compartments separately filled with glucose- or oxygen-sensing phosphorescent microparticles. We evaluated the response of the barcode hydrogels to fluctuating glucose levels over the physiological range under low oxygen conditions, demonstrating the controlled tuning of dynamic range and sensitivity. Moreover, the barcode sensor exhibited remarkable storage stability over 12 weeks, along with full reversibility and excellent reproducibility (∼6% variability in the phosphorescence lifetime) over nearly 50 devices. Electron beam sterilization had a negligible effect on the glucose response of the barcode sensors. Furthermore, our investigation revealed minimal phosphorescence lifetime changes in oxygen compartments while exhibiting increased lifetime in glucose-responsive compartments when subjected to alternating glucose concentrations (0 and 200 mg/dL), showcasing the sensor's multianalyte sensing capabilities without crosstalk between compartments. Additionally, the evaluation of chronic tissue response to sensors inserted in pigs revealed the appropriate biocompatibility of the barcodes as well as excellent material stability over many months. These findings support further development of similar technologies for introducing optical assays for multiple biomarkers that can provide continuous or on-demand feedback to individuals to manage chronic conditions.

Novel interfaces for internet of wearable electrochemical sensors

The integration of wearable devices, the Internet of Things (IoT), and advanced sensing platforms implies a significant paradigm shift in technological innovations and human interactions. The IoT technology allows continuous monitoring in real time. Thus, Internet of Wearables has made remarkable strides, especially in the field of medical monitoring. IoT-enabled wearable systems assist in early disease detection that facilitates personalized interventions and proactive healthcare management, thereby empowering individuals to take charge of their wellbeing. Until now, physical sensors have been successfully integrated into wearable devices for physical activity monitoring. However, obtaining biochemical information poses challenges in the contexts of fabrication compatibility and shorter operation lifetimes. IoT-based electrochemical wearable sensors allow real-time acquisition of data and interpretation of biomolecular information corresponding to biomarkers, viruses, bacteria and metabolites, extending the diagnostic capabilities beyond physical activity tracking. Thus, critical heath parameters such as glucose levels, blood pressure and cardiac rhythm may be monitored by these devices regardless of location and time. This work presents versatile electrochemical sensing devices across different disciplines, including but not limited to sports, safety and wellbeing by using IoT. It also discusses the detection principles for biomarkers and biofluid monitoring, and their integration into devices and advancements in sensing interfaces.

LIG-Based High-Sensitivity Multiplexed Sensing System for Simultaneous Monitoring of Metabolites and Electrolytes

With improvements in medical environments and the widespread use of smartphones, interest in wearable biosensors for continuous body monitoring is growing. We developed a wearable multiplexed bio-sensing system that non-invasively monitors body fluids and integrates with a smartphone application. The system includes sensors, readout circuits, and a microcontroller unit (MCU) for signal processing and wireless communication. Potentiometric and amperometric measurement methods were used, with calibration capabilities added to ensure accurate readings of analyte concentrations and temperature. Laser-induced graphene (LIG)-based sensors for glucose, lactate, Na+, K+, and temperature were developed for fast, cost-effective production. The LIG electrode's 3D porous structure provided an active surface area 16 times larger than its apparent area, resulting in enhanced sensor performance. The glucose and lactate sensors exhibited high sensitivity (168.15 and 872.08 μAmM-1cm-2, respectively) and low detection limits (0.191 and 0.167 μM, respectively). The Na+ and K+ sensors demonstrated sensitivities of 65.26 and 62.19 mVdec-1, respectively, in a concentration range of 0.01-100 mM. Temperature sensors showed an average rate of resistance change per °C of 0.25%/°C, within a temperature range of 20-40 °C, providing accurate body temperature monitoring.

Tear-Based Ocular Wearable Biosensors for Human Health Monitoring

Wearable tear-based biosensors have garnered substantial interest for real time monitoring with an emphasis on personalized health care. These biosensors utilize major tear biomarkers such as proteins, lipids, metabolites, and electrolytes for the detection and recording of stable biological signals in a non-invasive manner. The present comprehensive review delves deep into the tear composition along with potential biomarkers that can identify, monitor, and predict certain ocular diseases such as dry eye disease, conjunctivitis, eye-related infections, as well as diabetes mellitus. Recent technologies in tear-based wearable point-of-care medical devices, specifically the state-of-the-art and prospects of glucose, pH, lactate, protein, lipid, and electrolyte sensing from tear are discussed. Finally, the review addresses the existing challenges associated with the widespread application of tear-based sensors, which will pave the way for advanced scientific research and development of such non-invasive health monitoring devices.

Metasurface-Embedded Contact Lenses for Holographic Light Projection

Contact lenses have been instrumental in vision correction and are expected to be utilized in augmented reality (AR) displays through the integration of electronic and optical components. In optics, metasurfaces, an array of sub-wavelength nanostructures, have offered optical multifunctionality in an ultra-compact form factor, facilitating integration into various imaging, and display systems. However, transferring metasurfaces onto contact lenses remains challenging due to the non-biocompatible materials of extant imprinting methods and the structural instability caused by the swelling and shrinking of the wetted surface. Here, a biocompatible method is presented to transfer metasurfaces onto contact lenses using hyaluronic acid (HA) as a soft mold and to allow for holographic light projection. A high-efficiency metahologram is obtained with an all-metallic 3D meta-atom enhanced by the anisotropy of a rectangular structure, and a reflective background metal layer. A corrugated metal layer on the HA mold is supported with a SiO2 capping layer, to avoid unwanted wrinkles and to ensure structural stability when transferred to the surface of pliable and wettable contact lenses. Biocompatible method of transferring metasurfaces onto contact lenses promises the integration of diverse optical components, including holograms, lenses, gratings and more, to advance the visual experience for AR displays and human-computer interfaces.

Multifunctional nanomaterials for smart wearable diabetic healthcare devices

Wearable diabetic healthcare devices have attracted great attention for real-time continuous glucose monitoring (CGM) using biofluids such as tears, sweat, saliva, and interstitial fluid via noninvasive ways. In response to the escalating global demand for CGM, these devices enable proactive management and intervention of diabetic patients with incorporated drug delivery systems (DDSs). In this context, multifunctional nanomaterials can trigger the development of innovative sensing and management platforms to facilitate real-time selective glucose monitoring with remarkable sensitivity, on-demand drug delivery, and wireless power and data transmission. The seamless integration into wearable devices ensures patient's compliance. This comprehensive review evaluates the multifaceted roles of these materials in wearable diabetic healthcare devices, comparing their glucose sensing capabilities with conventionally available glucometers and CGM devices, and finally outlines the merits, limitations, and prospects of these devices. This review would serve as a valuable resource, elucidating the intricate functions of nanomaterials for the successful development of advanced wearable devices in diabetes management.

Magnetic augmentation through multi-gradient coupling enables direct and programmable profiling of circulating biomarkers

Conventional magnetic biosensing technologies have reduced analytical capacity for magnetic field dimensionality and require extensive sample processing. To address these challenges, we spatially engineer 3D magnetic response gradients for direct and programmable molecular detection in native biofluids. Named magnetic augmentation through triple-gradient coupling for high-performance detection (MATCH), the technology comprises gradient-distributed magnetic nanoparticles encapsulated within responsive hydrogel pillars and suspended above a magnetic sensor array. This configuration enables multi-gradient matching to achieve optimal magnetic activation, response and transduction, respectively. Through focused activation by target biomarkers, the platform preferentially releases sensor-proximal nanoparticles, generating response gradients that complement the sensor's intrinsic detection capability. By implementing an upstream module that recognizes different biomarkers and releases universal activation molecules, the technology achieves programmable detection of various circulating biomarkers in native plasma. It bypasses conventional magnetic labeling, completes in <60 minutes and achieves sensitive detection (down to 10 RNA and 1000 protein copies). We apply the MATCH to measure RNAs and proteins directly in patient plasma, achieving accurate cancer classification.

A Photoelectrochemical Retinomorphic Synapse

Reproducing human visual functions with artificial devices is a long-standing goal of the neuromorphic domain. However, emulating the chemical language communication of the visual system in fluids remains a grand challenge. Here, a "multi-color" hydrogel-based photoelectrochemical retinomorphic synapse is reported with unique chemical-ionic-electrical signaling in an aqueous electrolyte that enables, e.g., color perception and biomolecule-mediated synaptic plasticity. Based on the specific enzyme-catalyzed chromogenic reactions, three multifunctional colored hydrogels are developed, which can not only synergize with the Bi2S3 photogate to recognize the primary colors but also synergize with a given polymeric channel to promote the long-term memory of the system. A synaptic array is further constructed for sensing color images and biomolecule-coded information communication. Taking advantage of the versatile biochemistry, the biochemical-driven reversible photoelectric response of the cone cell is further mimicked. This work introduces rich chemical designs into retinomorphic devices, providing a perspective for replicating the human visual system in fluids.

Soft and Flexible Bioelectronic Micro-Systems for Electronically Controlled Drug Delivery

The concept of targeted and controlled drug delivery, which directs treatment to precise anatomical sites, offers benefits such as fewer side effects, reduced toxicity, optimized dosages, and quicker responses. However, challenges remain to engineer dependable systems and materials that can modulate host tissue interactions and overcome biological barriers. To stay aligned with advancements in healthcare and precision medicine, novel approaches and materials are imperative to improve effectiveness, biocompatibility, and tissue compliance. Electronically controlled drug delivery (ECDD) has recently emerged as a promising approach to calibrated drug delivery with spatial and temporal precision. This article covers recent breakthroughs in soft, flexible, and adaptable bioelectronic micro-systems designed for ECDD. It overviews the most widely reported operational modes, materials engineering strategies, electronic interfaces, and characterization techniques associated with ECDD systems. Further, it delves into the pivotal applications of ECDD in wearable, ingestible, and implantable medical devices. Finally, the discourse extends to future prospects and challenges for ECDD.

Scientific Production Dynamics in mHealth for Diabetes: Scientometric Analysis

BACKGROUND

The widespread use of mobile technologies in health care (mobile health; mHealth) has facilitated disease management, especially for chronic illnesses such as diabetes. mHealth for diabetes is an attractive alternative to reduce costs and overcome geographical and temporal barriers to improve patients' conditions.

OBJECTIVE

This study aims to reveal the dynamics of scientific publications on mHealth for diabetes to gain insights into who are the most prominent authors, countries, institutions, and journals and what are the most cited documents and current hot spots.

METHODS

A scientometric analysis based on a competitive technology intelligence methodology was conducted. An innovative 8-step methodology supported by experts was executed considering scientific documents published between 1998 and 2021 in the Science Citation Index Expanded database. Publication language, publication output characteristics, journals, countries and institutions, authors, and most cited and most impactful articles were identified.

RESULTS

The insights obtained show that a total of 1574 scientific articles were published by 7922 authors from 90 countries, with an average of 15 (SD 38) citations and 6.5 (SD 4.4) authors per article. These documents were published in 491 journals and 92 Web of Science categories. The most productive country was the United States, followed by the United Kingdom, China, Australia, and South Korea, and the top 3 most productive institutions came from the United States, whereas the top 3 most cited articles were published in 2016, 2009, and 2017 and the top 3 most impactful articles were published in 2016 and 2017.

CONCLUSIONS

This approach provides a comprehensive knowledge panorama of research productivity in mHealth for diabetes, identifying new insights and opportunities for research and development and innovation, including collaboration with other entities, new areas of specialization, and human resource development. The findings obtained are useful for decision-making in policy planning, resource allocation, and identification of research opportunities, benefiting researchers, health professionals, and decision makers in their efforts to make significant contributions to the advancement of diabetes science.

Power Scavenging Microsystem for Smart Contact Lenses

On-the-eye microsystems such as smart contacts for vision correction, health monitoring, drug delivery, and displaying information represent a new emerging class of low-profile (≤ 1 mm) wireless microsystems that conform to the curvature of the eyeball surface. The implementation of suitable low-profile power sources for eye-based microsystems on curved substrates is a major technical challenge addressed in this paper. The fabrication and characterization of a hybrid energy generation unit composed of a flexible silicon solar cell and eye-blinking activated Mg-O2 metal-air harvester capable of sustainably supplying electrical power to smart ocular devices are reported. The encapsulated photovoltaic device provides a DC output with a power density of 42.4 µW cm-2 and 2.5 mW cm-2 under indoor and outdoor lighting conditions, respectively. The eye-blinking activated Mg-air harvester delivers pulsed power output with a maximum power density of 1.3 mW cm-2. A power management circuit with an integrated 11 mF supercapacitor is used to convert the harvesters' pulsed voltages to DC, boost up the voltages, and continuously deliver ≈150 µW at a stable 3.3 V DC output. Uniquely, in contrast to wireless power transfer, the power pack continuously generates electric power and does not require any type of external accessories for operation.

Advanced nanomaterials for electrochemical sensors: application in wearable tear glucose sensing technology

In the last few decades, tear-based biosensors for continuous glucose monitoring (CGM) have provided new avenues for the diagnosis of diabetes. The tear CGMs constructed from nanomaterials have been extensively demonstrated by various research activities in this field and are gradually witnessing their most prosperous period. A timely and comprehensive review of the development of tear CGMs in a compartmentalized manner from a nanomaterials perspective would greatly broaden this area of research. However, to our knowledge, there is a lack of specialized reviews and comprehensive cohesive reports in this area. First, this paper describes the principles and development of electrochemical glucose sensors. Then, a comprehensive summary of various advanced nanomaterials recently reported for potential applications and construction strategies in tear CGMs is presented in a compartmentalized manner, focusing on sensing properties. Finally, the challenges, strategies, and perspectives used to design tear CGM materials are emphasized, providing valuable insights and guidance for the construction of tear CGMs from nanomaterials in the future.

Application of Silicone in Ophthalmology: A Review

This paper reviews the latest trends and applications of silicone in ophthalmology, especially related to intraocular lenses (IOLs). Silicone, or siloxane elastomer, as a synthetic polymer, has excellent biocompatibility, high chemical inertness, and hydrophobicity, enabling wide biomedical applications. The physicochemical properties of silicone are reviewed. A review of methods for mechanical and in vivo characterization of IOLs is presented as a prospective research area, since there are only a few available technologies, even though these properties are vital to ensure medical safety and suitability for clinical use, especially if long-term function is considered. IOLs represent permanent implants to replace the natural lens or for correcting vision, with the first commercial foldable lens made of silicone. Biological aspects of posterior capsular opacification have been reviewed, including the effects of the implanted silicone IOL. However, certain issues with silicone IOLs are still challenging and some conditions can prevent its application in all patients. The latest trends in nanotechnology solutions have been reviewed. Surface modifications of silicone IOLs are an efficient approach to further improve biocompatibility or to enable drug-eluting function. Different surface modifications, including coatings, can provide long-term treatments for various medical conditions or medical diagnoses through the incorporation of sensory functions. It is essential that IOL optical characteristics remain unchanged in case of drug incorporation and the application of nanoparticles can enable it. However, clinical trials related to these advanced technologies are still missing, thus preventing their clinical applications at this moment.

Patterning Techniques Based on Metallized Electrospun Nanofibers for Advanced Stretchable Electronics

Stretchable electronics have experienced remarkable progress, especially in sensors and wireless communication systems, attributed to their ability to conformably contact with rough or uneven surfaces. However, the development of complex, multifunctional, and high-precision stretchable electronics faces substantial challenges, including instability at rigid-soft interfaces and incompatibility with traditional high-precision patterning technologies. Metallized electrospun nanofibers emerge as a promising conductive filler, offering exceptional stretchability, electrical conductivity, transparency, and compatibility with existing patterning technologies. Here, this review focuses on the fundamental properties, preparation processes, patterning technologies, and application scenarios of conductive stretchable composites based on metallized nanofibers. Initially, it introduces the fabrication processes of metallized electrospun nanofibers and their advantages over alternative materials. It then highlights recent progress in patterning technologies, including collector collection, vapor deposition with masks, and lithography, emphasizing their role in enhancing precision and integration. Furthermore, the review shows the broad applicability and potential influence of metallized electrospun nanofibers in various fields through their use in sensors, wireless systems, semiconductor devices, and intelligent healthcare solutions. Ultimately, this review seeks to spark further innovation and address the prevailing challenges in stretchable electronics, paving the way for future breakthroughs in this dynamic field.

Vat photopolymerization printing of functionalized hydrogels on commercial contact lenses

Contact lenses are widely used for vision correction and cosmetic purposes. Smart contact lenses offer further opportunities as functionalized non-invasive devices capable of simultaneous vision correction, real-time health monitoring and patient specific drug delivery. Herein, a low-cost vat photopolymerization technique is developed for directly 3D printing functionalized structures on commercially available contact lenses. The process enables controlled deposition of functionalized hydrogels, in customizable patterns, on the commercial contact lens surface with negligible optical losses. Multi-functional contact lenses can also be 3D printed with multiple materials deposited at different regions of the contact lens. Herein, the functionalities of colour blindness correction and real-time UV monitoring are demonstrated, by employing three suitable dyes incorporated into 2-hydroxyethyl methacrylate (HEMA) hydrogel structures printed on contact lenses. The results suggest that 3D printing can pave the way towards simple production of low-cost patient specific smart contact lenses.

Synthesis of shape-programmable elastomer for a bioresorbable, wireless nerve stimulator

Materials that have the ability to manipulate shapes in response to stimuli such as heat, light, humidity and magnetism offer a means for versatile, sophisticated functions in soft robotics or biomedical implants, while such a reactive transformation has certain drawbacks including high operating temperatures, inherent rigidity and biological hazard. Herein, we introduce biodegradable, self-adhesive, shape-transformable poly (L-lactide-co-ε-caprolactone) (BSS-PLCL) that can be triggered via thermal stimulation near physiological temperature (∼38 °C). Chemical inspections confirm the fundamental properties of the synthetic materials in diverse aspects, and study on mechanical and biochemical characteristics validates exceptional stretchability up to 800 % and tunable dissolution behaviors under biological conditions. The integration of the functional polymer with a bioresorbable electronic system highlights potential for a wide range of biomedical applications.

Frequency-encoded eye tracking smart contact lens for human-machine interaction

Eye tracking techniques enable high-efficient, natural, and effortless human-machine interaction by detecting users' eye movements and decoding their attention and intentions. Here, a miniature, imperceptible, and biocompatible smart contact lens is proposed for in situ eye tracking and wireless eye-machine interaction. Employing the frequency encoding strategy, the chip-free and battery-free lens successes in detecting eye movement and closure. Using a time-sequential eye tracking algorithm, the lens has a great angular accuracy of <0.5°, which is even less than the vision range of central fovea. Multiple eye-machine interaction applications, such as eye-drawing, Gluttonous Snake game, web interaction, pan-tilt-zoom camera control, and robot vehicle control, are demonstrated on the eye movement model and in vivo rabbit. Furthermore, comprehensive biocompatibility tests are implemented, demonstrating low cytotoxicity and low eye irritation. Thus, the contact lens is expected to enrich approaches of eye tracking techniques and promote the development of human-machine interaction technology.

Mechanical Robustness Enhanced Flexible Antennas Using Ti3C2 MXene and Nanocellulose Composites for Noninvasive Glucose Sensing

Electromagnetic sensors with flexible antennas as sensing elements have attracted increasing attention in noninvasive continuous glucose monitoring for diabetic patients. The significant radiation performance loss of flexible antennas during mechanical deformation impairs the reliability of glucose monitoring. Here, we present flexible ultrawideband monopole antennas composed of Ti3C2 MXene and cellulose nanofibril (CNF) composite films for continuous glucose monitoring. The flexible MXene/CNF antenna with 20% CNF content can obtain a gain of up to 3.33 dBi and a radiation efficiency of up to 65.40% at a frequency range from 2.3 to 6.0 GHz. Compared with the pure MXene antenna, this antenna offers a comparable radiation performance and a lower performance loss in mechanical bending deformation. Moreover, the MXene/CNF antenna shows a stable response to fetal bovine serum/glucose, with a correlation of >0.9 at the reference glucose levels, and responds sensitively to the variations in blood glucose levels during human trials. The proposed strategy enhancing the mechanical robustness of MXene-based flexible antennas makes metallic two-dimensional nanomaterials more promising in wearable electromagnetic sensors.

Photonics-powered augmented reality skin electronics for proactive healthcare: multifaceted opportunities

Rapid technological advancements have created opportunities for new solutions in various industries, including healthcare. One exciting new direction in this field of innovation is the combination of skin-based technologies and augmented reality (AR). These dermatological devices allow for the continuous and non-invasive measurement of vital signs and biomarkers, enabling the real-time diagnosis of anomalies, which have applications in telemedicine, oncology, dermatology, and early diagnostics. Despite its many potential benefits, there is a substantial information vacuum regarding using flexible photonics in conjunction with augmented reality for medical purposes. This review explores the current state of dermal augmented reality and flexible optics in skin-conforming sensing platforms by examining the obstacles faced thus far, including technical hurdles, demanding clinical validation standards, and problems with user acceptance. Our main areas of interest are skills, chiroptical properties, and health platform applications, such as optogenetic pixels, spectroscopic imagers, and optical biosensors. My skin-enhanced spherical dichroism and powerful spherically polarized light enable thorough physical inspection with these augmented reality devices: diabetic tracking, skin cancer diagnosis, and cardiovascular illness: preventative medicine, namely blood pressure screening. We demonstrate how to accomplish early prevention using case studies and emergency detection. Finally, it addresses real-world obstacles that hinder fully realizing these materials' extraordinary potential in advancing proactive and preventative personalized medicine, including technical constraints, clinical validation gaps, and barriers to widespread adoption.

Technological Advances of Wearable Device for Continuous Monitoring of In Vivo Glucose

Managing diabetes is a chronic challenge today, requiring monitoring and timely insulin injections to maintain stable blood glucose levels. Traditional clinical testing relies on fingertip or venous blood collection, which has facilitated the emergence of continuous glucose monitoring (CGM) technology to address data limitations. Continuous glucose monitoring technology is recognized for tracking long-term blood glucose fluctuations, and its development, particularly in wearable devices, has given rise to compact and portable continuous glucose monitoring devices, which facilitates the measurement of blood glucose and adjustment of medication. This review introduces the development of wearable CGM-based technologies, including noninvasive methods using body fluids and invasive methods using implantable electrodes. The advantages and disadvantages of these approaches are discussed as well as the use of microneedle arrays in minimally invasive CGM. Microneedle arrays allow for painless transdermal puncture and are expected to facilitate the development of wearable CGM devices. Finally, we discuss the challenges and opportunities and look forward to the biomedical applications and future directions of wearable CGM-based technologies in biological research.

Wireless Battery-free and Fully Implantable Organ Interfaces

Advances in soft materials, miniaturized electronics, sensors, stimulators, radios, and battery-free power supplies are resulting in a new generation of fully implantable organ interfaces that leverage volumetric reduction and soft mechanics by eliminating electrochemical power storage. This device class offers the ability to provide high-fidelity readouts of physiological processes, enables stimulation, and allows control over organs to realize new therapeutic and diagnostic paradigms. Driven by seamless integration with connected infrastructure, these devices enable personalized digital medicine. Key to advances are carefully designed material, electrophysical, electrochemical, and electromagnetic systems that form implantables with mechanical properties closely matched to the target organ to deliver functionality that supports high-fidelity sensors and stimulators. The elimination of electrochemical power supplies enables control over device operation, anywhere from acute, to lifetimes matching the target subject with physical dimensions that supports imperceptible operation. This review provides a comprehensive overview of the basic building blocks of battery-free organ interfaces and related topics such as implantation, delivery, sterilization, and user acceptance. State of the art examples categorized by organ system and an outlook of interconnection and advanced strategies for computation leveraging the consistent power influx to elevate functionality of this device class over current battery-powered strategies is highlighted.

Wireless magnetoelectrically powered organic light-emitting diodes

Compact wireless light sources are a fundamental building block for applications ranging from wireless displays to optical implants. However, their realization remains challenging because of constraints in miniaturization and the integration of power harvesting and light-emission technologies. Here, we introduce a strategy for a compact wirelessly powered light-source that consists of a magnetoelectric transducer serving as power source and substrate and an antiparallel pair of custom-designed organic light-emitting diodes. The devices operate at low-frequency ac magnetic fields (~100 kHz), which has the added benefit of allowing operation multiple centimeters deep inside watery environments. By tuning the device resonance frequency, it is possible to separately address multiple devices, e.g., to produce light of distinct colors, to address individual display pixels, or for clustered operation. By simultaneously offering small size, individual addressing, and compatibility with challenging environments, our devices pave the way for a multitude of applications in wireless displays, deep tissue treatment, sensing, and imaging.

Smart Contact Lenses for Healthcare Monitoring and Therapy

The eye contains a wealth of physiological information and offers a suitable environment for noninvasive monitoring of diseases via smart contact lens sensors. Although extensive research efforts recently have been undertaken to develop smart contact lens sensors, they are still in an early stage of being utilized as an intelligent wearable sensing platform for monitoring various biophysical/chemical conditions. In this review, we provide a general introduction to smart contact lenses that have been developed for disease monitoring and therapy. First, different disease biomarkers available from the ocular environment are summarized, including both physical and chemical biomarkers, followed by the commonly used materials, manufacturing processes, and characteristics of contact lenses. Smart contact lenses for eye-drug delivery with advancing technologies to achieve more efficient treatments are then introduced as well as the latest developments for disease diagnosis. Finally, sensor communication technologies and smart contact lenses for antimicrobial and other emerging bioapplications are also discussed as well as the challenges and prospects of the future development of smart contact lenses.

Signal transduction interfaces for field-effect transistor-based biosensors

Biosensors based on field-effect transistors (FETs) are suitable for use in miniaturized and cost-effective healthcare devices. Various semiconductive materials can be applied as FET channels for biosensing, including one- and two-dimensional materials. The signal transduction interface between the biosample and the channel of FETs plays a key role in translating electrochemical reactions into output signals, thereby capturing target ions or biomolecules. In this Review, distinctive signal transduction interfaces for FET biosensors are introduced, categorized as chemically synthesized, physically structured, and biologically induced interfaces. The Review highlights that these signal transduction interfaces are key in controlling biosensing parameters, such as specificity, selectivity, binding constant, limit of detection, signal-to-noise ratio, and biocompatibility.

Flexible and Stretchable Light-Emitting Diodes and Photodetectors for Human-Centric Optoelectronics

Optoelectronic devices with unconventional form factors, such as flexible and stretchable light-emitting or photoresponsive devices, are core elements for the next-generation human-centric optoelectronics. For instance, these deformable devices can be utilized as closely fitted wearable sensors to acquire precise biosignals that are subsequently uploaded to the cloud for immediate examination and diagnosis, and also can be used for vision systems for human-interactive robotics. Their inception was propelled by breakthroughs in novel optoelectronic material technologies and device blueprinting methodologies, endowing flexibility and mechanical resilience to conventional rigid optoelectronic devices. This paper reviews the advancements in such soft optoelectronic device technologies, honing in on various materials, manufacturing techniques, and device design strategies. We will first highlight the general approaches for flexible and stretchable device fabrication, including the appropriate material selection for the substrate, electrodes, and insulation layers. We will then focus on the materials for flexible and stretchable light-emitting diodes, their device integration strategies, and representative application examples. Next, we will move on to the materials for flexible and stretchable photodetectors, highlighting the state-of-the-art materials and device fabrication methods, followed by their representative application examples. At the end, a brief summary will be given, and the potential challenges for further development of functional devices will be discussed as a conclusion.