Flexible and stretchable electronics and optoelectronics configured in soft, water resistant formats uniquely address seminal challenges in biomedicine. Over the past decade, there has been enormous ...progress in the materials, designs, and manufacturing processes for flexible/stretchable system subcomponents, including transistors, amplifiers, bio‐sensors, actuators, light emitting diodes, photodetector arrays, photovoltaics, energy storage elements, and bare die integrated circuits. Nanomaterials prepared using top‐down processing approaches and synthesis‐based bottom‐up methods have helped resolve the intrinsic mechanical mismatch between rigid/planar devices and soft/curvilinear biological structures, thereby enabling a broad range of non‐invasive, minimally invasive, and implantable systems to address challenges in biomedicine. Integration of therapeutic functional nanomaterials with soft bioelectronics demonstrates therapeutics in combination with unconventional diagnostics capabilities. Recent advances in soft materials, devices, and integrated systems are reviewes, with representative examples that highlight the utility of soft bioelectronics for advanced medical diagnostics and therapies.
The technological advances in the field of flexible and stretchable electronics have burgeoned tremendously over the past decade, enabling multifunctional bio integrated electronics and optoelectronics systems. Recent progress in nanomaterials, device design, and system integration strategies for flexible and stretchable bioelectronics systems is reviewed in the context of wearable sensors/actuators, minimally invasive surgical tools, and soft implantable devices.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Cardiovascular disease is the leading cause of death and has dramatically increased in recent years. Continuous cardiac monitoring is particularly important for early diagnosis and prevention, and ...flexible and stretchable electronic devices have emerged as effective tools for this purpose. Their thin, soft, and deformable features allow intimate and long‐term integration with biotissues, which enables continuous, high‐fidelity, and sometimes large‐area cardiac monitoring on the skin and/or heart surface. In addition to monitoring, intimate contact is also crucial for high‐precision therapies. Combined with tissue engineering, soft bioelectronics have also demonstrated the capability to repair damaged cardiac tissues. This review highlights the recent advances in wearable and implantable devices based on flexible and stretchable electronics for cardiovascular monitoring and therapy. First, wearable/implantable soft bioelectronics for cardiovascular monitoring (e.g., the electrocardiogram, blood pressure, and oxygen saturation level) are reviewed. Then, advances in cardiovascular therapy based on soft bioelectronics (e.g., mesh pacing, ablation, robotic sleeves, and electronic stents) are discussed. Finally, device‐assisted tissue engineering therapy (e.g., functional electronic scaffolds and in vitro cardiac platforms) is discussed.
Over the past few decades, soft bioelectronics have been widely adopted in biomedical research fields to address limitations in each field. Here, wearable and implantable devices based on flexible and stretchable electronics for cardiovascular monitoring and therapy that overcome the problems with conventional treatments are reviewed. In addition, the emerging field of device‐assisted tissue engineering is highlighted.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The diverse vision systems found in nature can provide interesting design inspiration for imaging devices, ranging from optical subcomponents to digital cameras and visual prostheses, with more ...desirable optical characteristics compared to conventional imagers. The advantages of natural vision systems include high visual acuity, wide field of view, wavelength‐free imaging, improved aberration correction and depth of field, and high motion sensitivity. Recent advances in soft materials, ultrathin electronics, and deformable optoelectronics have facilitated the realization of novel processes and device designs that mimic biological vision systems. This review highlights recent progress and continued efforts in the research and development of bioinspired artificial eyes. At first, the configuration of two representative eyes found in nature: a single‐chambered eye and a compound eye, is explained. Then, advances in bioinspired optic components and image sensors are discussed in terms of materials, optical/mechanical designs, and integration schemes. Subsequently, novel visual prostheses as representative application examples of bioinspired artificial eyes are described.
Vision systems in nature are highly attractive in the field of imaging devices due to the applicability for optical subcomponents, digital cameras, and visual prostheses. The most recent advances in bioinspired imaging systems based on soft materials/device designs, ultrathin electronics, and deformable optoelectronics are reviewed. A representative application example of the bioinspired artificial eye, novel visual prostheses, is also discussed.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Highly conductive and intrinsically stretchable electrodes are vital components of soft electronics such as stretchable transistors and circuits, sensors and actuators, light-emitting diode arrays, ...and energy harvesting devices. Many kinds of conducting nanomaterials with outstanding electrical and mechanical properties have been integrated with elastomers to produce stretchable conductive nanocomposites. Understanding the characteristics of these nanocomposites and assessing the feasibility of their fabrication are therefore critical for the development of high-performance stretchable conductors and electronic devices. We herein summarise the recent advances in stretchable conductors based on the percolation networks of nanoscale conductive fillers in elastomeric media. After discussing the material-, dimension-, and size-dependent properties of conductive fillers and their implications, we highlight various techniques that are used to reduce the contact resistance between the conductive filler materials. Furthermore, we categorize elastomer matrices with different stretchabilities and mechanical properties based on their polymeric chain structures. Then, we discuss the fabrication techniques of stretchable conductive nanocomposites toward their use in soft electronics. Finally, we provide representative examples of stretchable device applications and conclude the review with a brief outlook for future research.
This article reviews the cascade strategy of stretchable conductive nanocomposites where various filler materials are processed for stretchable electronic applications.
Stretchable electronics are mechanically compatible with a variety of objects, especially with the soft curvilinear contours of the human body, enabling human‐friendly electronics applications that ...could not be achieved with conventional rigid electronics. Therefore, extensive research effort has been devoted to the development of stretchable electronics, from research on materials and unit device, to fully integrated systems. In particular, material‐processing technologies that encompass the synthesis, assembly, and patterning of intrinsically stretchable electronic materials have been actively investigated and have provided many notable breakthroughs for the advancement of stretchable electronics. Here, the latest studies of such material‐based approaches are reviewed, mainly focusing on intrinsically stretchable electronic nanocomposites that generally consist of conducting/semiconducting filler materials inside or on elastomer backbone matrices. Various approaches for fabricating these intrinsically stretchable electronic materials are presented, including the blending of electronic fillers into elastomer matrices, the formation of bi‐layered heterogeneous electronic‐layer and elastomer support‐layer structures, and modifications to polymeric molecular structures in order to impart stretchability. Detailed descriptions of the various conducting/semiconducting composites prepared by each method are provided, along with their electrical/mechanical properties and examples of device applications. To conclude, a brief future outlook is presented.
The latest research developments and progress regarding material‐based approaches for the fabrication of stretchable electronics are comprehensively reviewed. Detailed descriptions of various stretchable conducting/semiconducting composites are given, along with their electrical/mechanical properties, material processing strategies, and examples of device applications. In addition, the outlook for future research in this field is discussed.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Recent technological advances in nanomaterials have driven the development of high‐performance light‐emitting devices with flexible and stretchable form factors. Deformability in such devices is ...mainly achieved by replacing the rigid materials in the device components with flexible nanomaterials and their assemblies (e.g., carbon nanotubes, silver nanowires, graphene, and quantum dots) or with intrinsically soft materials and their composites (e.g., polymers and elastomers). Downscaling the dimensions of the functional materials to the nanometer range dramatically decreases their flexural rigidity, and production of polymer/elastomer composites with functional nanomaterials provides light‐emitting devices with flexibility and stretchability. Furthermore, monolithic integration of these light‐emitting devices with deformable sensors furnishes the resulting display with various smart functions such as force/capacitive touch‐based data input, personalized health monitoring, and interactive human–machine interfacing. These ultrathin, lightweight, and deformable smart optoelectronic devices have attracted widespread interest from materials scientists and device engineers. Here, a comprehensive review of recent progress concerning these flexible and stretchable smart displays is presented with a focus on materials development, fabrication techniques, and device designs. Brief overviews of an integrated system of advanced smart displays and cutting‐edge wearable sensors are also presented, and, to conclude, a discussion of the future research outlook is given.
The recent research developments and progress regarding flexible and stretchable smart displays are reviewed comprehensively. Important advancements concerning materials development, fabrication techniques, and device designs are summarized, compared, and discussed, with a detailed description of smart display applications. In addition, the outlook for future research in this field is discussed.
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Blood glucose concentration is a key indicator of patients' health, particularly for symptoms associated with diabetes mellitus. Because of the large number of diabetic patients, many approaches for ...glucose measurement have been studied to enable continuous and accurate glucose level monitoring. Among them, electrochemical analysis is prominent because it is simple and quantitative. This technology has been incorporated into commercialized and research‐level devices from simple test strips to wearable devices and implantable systems. Although directly monitoring blood glucose assures accurate information, the invasive needle‐pinching step to collect blood often results in patients (particularly young patients) being reluctant to adopt the process. An implantable glucose sensor may avoid the burden of repeated blood collections, but it is quite invasive and requires periodic replacement of the sensor owing to biofouling and its short lifetime. Therefore, noninvasive methods to estimate blood glucose levels from tears, saliva, interstitial fluid (ISF), and sweat are currently being studied. This review discusses the evolution of enzyme‐based electrochemical glucose sensors, including materials, device structures, fabrication processes, and system engineering. Furthermore, invasive and noninvasive blood glucose monitoring methods using various biofluids or blood are described, highlighting the recent progress in the development of enzyme‐based glucose sensors and their integrated systems.
Over the past decades, the electrochemical glucose sensors for diabetes care have improved tremendously, which enable a convenient tracking of blood glucose levels continuously. Here, the basic principles and recent progress in enzyme‐based electrochemical glucose sensors are reviewed, as well as their application to noninvasive blood glucose monitoring methods and to the conventional invasive methods.
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Wearable bioelectronic technologies have made significant progresses in personalized health management through non‐invasive monitoring of health indicators. However, current wearable systems cannot ...measure biochemical information and physiological signals simultaneously, which limits integrated data analysis and their widespread clinical applications. Here, an integrated multifunctional wearable health management system composed of a disposable sweat‐based glucose sensing strip and a wearable smart band is reported. The integrated system with control software electrochemically analyzes sweat glucose levels and continuously monitors vital signs (i.e., heart rate, blood oxygen saturation level, and physical activity). Different sweat collecting sites and sweat generation methods are tested in short‐ and long‐term studies with multiple human subjects by using the developed wearable system, leading to optimized protocols for health monitoring. By combining sweat glucose data and physiological monitoring data, pre‐ and post‐exercise blood glucose levels and blood glucose changes resulting from physical activities are reliably estimated, providing key information for preventing hypoglycemic shock during intense exercise. The integrated wearable system offers a novel comprehensive personalized health management strategy through combined analysis of key metabolic and physiological health indicators.
An integrated multifunctional wearable health monitoring system that consists of a disposable sweat‐based glucose sensing strip and a wearable smart band is developed for pre‐/post‐exercise glucose‐level estimation and comprehensive personalized health management. Multiple short‐term human studies under various conditions are performed, and optimized protocols for the integrated system to perform accurate and user‐friendly sweat‐based metabolic data analysis are reported.
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A wearable fabric‐based integrated power‐supply system that generates energy triboelectrically using human activity and stores the generated energy in an integrated supercapacitor is developed. This ...system can be utilized as either a self‐powered activity monitor or as a power supply for external wearable sensors. These demonstrations give new insights for the research of wearable electronics.
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