Engineering conducting polymer thin films with morphological homogeneity and long-range molecular ordering is intriguing to achieve high-performance organic electronics. Polyaniline (PANI) has attracted considerable interest due to its appealing electrical conductivity and diverse chemistry. However, the synthesis of large-area PANI thin film and the control of its crystallinity and thickness remain challenging because of the complex intermolecular interactions of aniline oligomers. Here we report a facile route combining air-water interface and surfactant monolayer as templates to synthesize crystalline quasi-two-dimensional (q2D) PANI with lateral size ~50 cm2 and tunable thickness (2.6–30 nm). The achieved q2D PANI exhibits anisotropic charge transport and a lateral conductivity up to 160 S cm−1 doped by hydrogen chloride (HCl). Moreover, the q2D PANI displays superior chemiresistive sensing toward ammonia (30 ppb), and volatile organic compounds (10 ppm). Our work highlights the q2D PANI as promising electroactive materials for thin-film organic electronics.

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...

Recent years have witnessed thriving progress of flexible and portable electronics, with very high demand for cost-effective and tailor-made multifunctional devices. Here, we report on an ingenious origami hierarchical sensor array (OHSA) written with a conductive ink. Thanks to origami as a controllable hierarchical framework for loading ink material, we have demonstrated that OHSA possesses unique time-space-resolved, high-discriminative pattern recognition (TSR-HDPR) features, qualifying it as a smart sensing device for simultaneous sensing and distinguishing of complex physical and chemical stimuli, including temperature, relative humidity, light and volatile organic compounds (VOCs). Of special importance, OSHA has shown very high sensitivity in differentiating between structural isomers and chiral enantiomers of VOCs – opening a door for wide variety of unique opportunities in several length scales.

Wearable strain sensors have been attracting special attention in the detection of human posture and activity, as well as for the assessment of physical rehabilitation and kinematics. However, it is a challenge to fabricate stretchable and comfortable‐to‐wear permeable strain sensors that can provide highly accurate and continuous motion recording while exerting minimal constraints and maintaining low interference with the body. Herein, covalently grafting nanofibrous polyaniline (PANI) onto stretchable elastomer nanomeshes is reported to obtain a freestanding ultrathin (varying from 300 to 10 000 nm) strain sensor that has high gas permeability (10–33 mg h–1). The sensor demonstrates a low weight and can be directly laminated onto the dynamic human skin for long periods of time. The sensor, which produces an intimate connection with solid or living objects, has a stable performance with excellent sustainability, linearity, durability, and low hysteresis. It exibits excellent performance for continuous interrogation of complex movements, mimicking muscle activities, and resembling brain activity. This includes a very precise discrimination of bending and twisting stimuli at different angles (1–180°) and speeds (3–18 rpm) and very low exertion of counter‐interference. These results imply the utility of this appraoch for advanced developments of robotic e‐skins or e‐muscles.

Flexible sensors can be widely used in future wearable devices to monitor people's health states. However, most of the sensors are sensitive to humidity and bending effects, limiting their application in a real-world environment. A new strategy is proposed for obtaining flexible sensors with good tolerance to humidity. By integrating a hydrophobic layer on the surface of doped polyaniline, a flexible sensor that can resist water response with a concentration up to 350 ppm is developed. Good resilience against mechanical bending is also achieved in this flexible sensor. These results may trigger a renaissance in flexible sensor applications for disease diagnosing by wearable devices.