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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.

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.

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Flexible and wearable electronic sensors are useful for the early diagnosis and monitoring of an individual's health state. Sampling of volatile organic compounds (VOCs) derived from human breath/skin or monitoring abrupt changes in heart-beat/breath rate should allow noninvasive monitoring of disease states at an early stage. Nevertheless, for many reported wearable sensing devices, interaction with the human body leads incidentally to unavoidable scratches and/or mechanical cuts and bring about malfunction of these devices. We now offer proof-of-concept of nanoparticle-based flexible sensor arrays with fascinating self-healing abilities. By integrating a self-healable polymer substrate with 5 kinds of functionalized gold nanoparticle films, a sensor array gives a fast self-healing (<3 h) and attractive healing efficiency in both the substrate and sensing films. The proposed platform was used in sensing pressure variation and 11 kinds of VOCs. The sensor array had satisfactory sensitivity, a low detection limit, and promising discrimination features in monitoring both of VOCs and pressure variation, even after full healing. These results presage a new type of smart sensing device, with a desirable performance in the possible detection and/or clinical application for a number of different purposes.

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.

An ambipolar poly(diketopyrrolopyrrole-terthiophene)-based field-effect transistor (FET) sensitively detects xylene isomers at low ppm levels with multiple sensing features. Combined with pattern-recognition algorithms, a sole ambipolar FET sensor, rather than arrays of sensors, can discriminate highly similar xylene structural isomers from one another.

and motion; they would revolutionize present prognosis methods by introducing fast, cheap, and noninvasive alternatives. [3,5,8,13] Soft and flexible sensors can satisfy several mechanical requirements, including conformal attachment to the body, stretchability, and softness, giving greater sensing efficiency. [3,4,6,8,10,14,15] However, devices with these properties are susceptible to mechanical/structural damage (e.g., cracks and scratches), which can result from the combined effect of their soft nature and incompatibility in mechanical stress with human skin. Inevitably, this leads to a lower durability, decreased life-time, and reduced performance in many cases. [16][17][18] To address this issue, one can mimic biological systems by introducing a self-healing capability-a vital property for many organisms in nature-into flexible and soft devices, allowing the recovery of damages without external interventions. [18][19][20][21][22] Excellent progress in the development of new self-healing materials has been made in nonelectronic systems as well as in chemiresistors, supercapacitors, and electrochemical devices. [22][23][24] Nevertheless, field effect transistors (FETs) with extractable multiparameters, offering considerable advantages as a sensor over other competing strategies by delivering a label-free response using a simple electronic readout setup that can be easily miniaturized by employing printed circuit technologies, [25] has not yet been targeted. To prepare FETs, self-healing insulator (dielectric), conductive (electrodes), and semiconductive (channel) materials are required, with the latter being the more challenging. The difficulty of obtaining such material arises from the rigidity of semiconductors because of their conjugated and high crystalline structure, which is contradictory to the softness and high chain mobility of selfhealing materials. Recently, Bao and co-workers have succeeded in synthesizing a healable semiconducting polymer based on 3,6-di(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione repeating units and nonconjugated 2,6-pyridine dicarboxamide moieties with a µ h of ≈1.4 cm 2 V −1 s −1 , ≈10 6 on/off ratio, and high operating voltages up to −60 V. Nevertheless, the healing process needed solvent treatment or high temperatures for electrical and mechanical recovery with the limitation of selfhealable damage size (<100 nm nanocracks) as well. [26] Indeed, A flexible and stretchable field-effect transistor (FET) is an essential element in a number of modern electronics. To realize the potential of this device in harsh real-world conditions and to extend its application spectrum, new functionalities are needed to be introduced into the device. Here, solution-processable elements based on carbon nanotubes that empower flexible and stretchable FET with high hole-mobility (µ h ≈ 10 cm 2 V −1 s −1 ) and relatively low operating voltages (<8 V) and that retain self-healing properties of all FET components are reported. The device has repeatable intrinsic and autonomic self-heali...