This book offers an outlook into the challenges in the continuing development of volatile biomarkers and their wider availability to healthcare research and industries.
Wearable devices are gaining considerable attention owing to the ease with which they can collect crucial information in real‐time, both continuously and noninvasively, regarding a wearer's health. A ...concise summary is given of the three main elements that enable autonomous detection and monitoring of the likelihood or the existence of a health‐risk state in continuous and real‐time modes, with an emphasis on emerging materials and fabrication techniques in the relevant fields. The first element is the sensing technology used in the noninvasive detection of physiological markers relevant to the state of health. The second element is self‐powered devices for longer periods of use by drawing energy from bodily movement and temperature. The third element is the self‐healing properties of the materials used in the wearable devices to extended usage if they become scratched or cut. Promises and challenges of the separately reviewed parts and the combined parts are presented and discussed. Ideas regarding further improvement of skin‐based wearable devices are also presented and discussed.
Detection of disease at an early stage, before it becomes symptomatic, is receiving significant attention. The materials and their devices of physiological parameters sensing, energy harvesting, self‐powered platforms, and self‐healing technology are reviewed. A perspective is given and the future development direction of autonomous and noninvasive monitoring of physiological markers is discussed.
The analysis of volatile organic compounds in exhaled breath samples represents a new frontier in medical diagnostics because it is a noninvasive and potentially inexpensive way to detect illnesses. ...Clinical trials with spectrometry and spectroscopy techniques, the standard volatile-compound detection methods, have shown the potential for diagnosing illnesses including cancer, multiple sclerosis, Parkinson’s disease, tuberculosis, diabetes, and more via breath tests. Unfortunately, this approach requires expensive equipment and high levels of expertise to operate the necessary instruments, and the tests must be done quickly and use preconcentration techniques, all of which impede its adoption. Sensing matrices based on nanomaterials are likely to become a clinical and laboratory diagnostic tool because they are significantly smaller, easier-to-use, and less expensive than spectrometry or spectroscopy. An ideal nanomaterial-based sensor for breath testing should be sensitive at very low concentrations of volatile organic compounds, even in the presence of environmental or physiological confounding factors. It should also respond rapidly and proportionately to small changes in concentration and provide a consistent output that is specific to a given volatile organic compound. When not in contact with the volatile organic compounds, the sensor should quickly return to its baseline state or be simple and inexpensive enough to be disposable. Several reviews have focused on the methodological, biochemical, and clinical aspects of breath analysis in attempts to bring breath testing closer to practice for comprehensive disease detection. This Account pays particular attention to the technological gaps and confounding factors that impede nanomaterial-sensor-based breath testing, in the hope of directing future research and development efforts towards the best possible approaches to overcome these obstacles. We discuss breath testing as a complex process involving numerous steps, each of which has several possible technological alternatives with advantages and drawbacks that might affect the performance of the nanomaterial-based sensors in a breath-testing system. With this in mind, we discuss how to choose nanomaterial-based sensors, considering the profile of the targeted breath markers and the possible limitations of the approach, and how to design the surrounding breath-testing setup. We also discuss how to tailor the dynamic range and selectivity of the applied sensors to detect the disease-related volatile organic compounds of interest. Finally, we describe approaches to overcome other obstacles by improving the sensing elements and the supporting techniques such as preconcentration and dehumidification.
The demand for interfacing electronics in everyday life is rapidly accelerating, with an ever‐growing number of applications in wearable electronics and electronic skins for robotics, prosthetics, ...and other purposes. Soft sensors that efficiently detect environmental or biological/physiological stimuli have been extensively studied due to their essential role in creating the necessary interfaces for these applications. Unfortunately, due to their natural softness, these sensors are highly sensitive to structural and mechanical damage. The integration of natural properties, such as self‐healing, into these systems should improve their reliability, stability, and long‐term performance. Recent studies on self‐healing soft sensors for varying chemical and physical parameters are herein reviewed. In addition, contemporary studies on material design, device structure, and fabrication methods for sensing platforms are also discussed. Finally, the main challenges and future perspectives in this field are introduced, while focusing on the most promising examples and directions already reported.
The emerging field of self‐healing soft sensing platforms is presented and discussed, while pointing out pathways to be followed by materials designers, synthetic chemists, and engineers for developing further high‐performance and durable sensing devices.
Wound dressings based on nanomaterials play a crucial role in wound treatment and are widely used in a whole range of medical settings, from minor to life-threatening tissue injuries. This article ...presents an educational review on the accumulating knowledge in this multidisciplinary area to lay out the challenges and opportunities that lie ahead and ignite the further and faster development of clinically valuable technologies. The review analyzes the functional advantages of nanomaterial-based gauzes and hydrogels as well as hybrid structures thereof. On this basis, the review presents state-of-the-art advances to transfer the (semi)blind approaches to the evaluation of a wound state to smart wound dressings that enable real-time monitoring and diagnostic functions that could help in wound evaluation during healing. This review explores the translation of nanomaterial-based wound dressings and related medical aspects into real-world use. The ongoing challenges and future opportunities associated with nanomaterial-based wound dressings and related clinical decisions are presented and reviewed.
A concise, although admittedly non‐exhaustive, didactic summary is given of some of the main concepts and approaches related to recent advances and developments to enable autonomous detection and ...monitoring of the likelihood or existence of a health risk state in continuous and real‐time modes. To give a comprehensive statement, different aspects of these advanced materials and related devices are presented and discussed, such as: flexible sensors used for non‐invasive detection of health‐related physiological markers; self‐powered materials to enable extended usage periods by harvesting energy from body movement and temperature; and self‐healing properties of the materials used on the wearable devices to enable extended usage periods if scratched or cut. The linkage of these advanced materials and technologies together is particularly specified. Some of the strong and weak points in the development of each wearable material/device are clearly highlighted and criticized. Several ideas regarding further improvement of skin‐based wearable devices are also discussed.
State‐of‐the‐art and independent developments of self‐powered, self‐sensing, and self‐healing materials and/or devices are reported to procure autonomous flexible sensors. Two or three “self”‐concepts can be combined into a single sensing platform, connecting to the “Internet of Things.” The autonomous flexible sensors are expected to contribute greatly to health monitoring.
Devices integrated with self‐healing ability can benefit from long‐term use as well as enhanced reliability, maintenance and durability. This progress report reviews the developments in the field of ...self‐healing polymers/composites and wearable devices thereof. One part of the progress report presents and discusses several aspects of the self‐healing materials chemistry (from non‐covalent to reversible covalent‐based mechanisms), as well as the required main approaches used for functionalizing the composites to enhance their electrical conductivity, magnetic, dielectric, electroactive and/or photoactive properties. The second and complementary part of the progress report links the self‐healing materials with partially or fully self‐healing device technologies, including wearable sensors, supercapacitors, solar cells and fabrics. Some of the strong and weak points in the development of each self‐healing device are clearly highlighted and criticized, respectively. Several ideas regarding further improvement of soft self‐healing devices are proposed.
Wearable devices that can negate the detrimental effects of scratched and/or mechanical cuts, and that restore the mechanical/electrical/chemical properties by a self‐healing mechanism are reviewed and discussed. The materials chemistry of self‐healing polymers/composites is reviewed and their use in/as wearable sensors, supercapacitors, and solar cells is discussed.
A non‐biological and flexible self‐healing platform has tailored sensitivity toward one or a combination of pressure, strain, gas analytes, and temperature. For demonstration, a complete self‐healing ...device is described in the form of a bendable and stretchable chemiresistor, where every part is self‐healing.
Highlights
This review gives a thinking based on the generic mechanisms rather than simply dividing them as different types of combination of materials, which is unique and valuable for understanding ...and developing the novel hybrid materials in the future.
The hybrid materials, their sensing mechanism, and their applications are systematically reviewed. Critical thinking and ideas regarding the orientation of the development of hybrid material-based gas sensor in the future are also discussed.
Chemi-resistive sensors based on hybrid functional materials are promising candidates for gas sensing with high responsivity, good selectivity, fast response/recovery, great stability/repeatability, room-working temperature, low cost, and easy-to-fabricate, for versatile applications. This progress report reviews the advantages and advances of these sensing structures compared with the single constituent, according to five main sensing forms: manipulating/constructing heterojunctions, catalytic reaction, charge transfer, charge carrier transport, molecular binding/sieving, and their combinations. Promises and challenges of the advances of each form are presented and discussed. Critical thinking and ideas regarding the orientation of the development of hybrid material-based gas sensor in the future are discussed.
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