Fibrous material with high strength and large stretchability is an essential component of high‐performance wearable electronic devices. Wearable electronic systems require a material that is strong to ensure durability and stability, and a wide range of strain to expand their applications. However, it is still challenging to manufacture fibrous materials with simultaneously high mechanical strength and the tensile property. Herein, the ultra‐robust (≈17.6 MPa) and extensible (≈700%) conducting microfibers are developed and demonstrated their applications in fabricating fibrous mechanical sensors. The mechanical sensor shows high sensitivity in detecting strains that have high strain resolution and a large detection range (from 0.0075% to 400%) simultaneously. Moreover, low frequency vibrations between 0 and 40 Hz are also detected, which covers most tremors that occur in the human body. As a further step, a wearable and smart health‐monitoring system has been developed using the fibrous mechanical sensor, which is capable of monitoring health‐related physiological signals, including muscle movement, body tremor, wrist pulse, respiration, gesture, and six body postures to predict and diagnose diseases, which will promote the wearable telemedicine technology.
Synthesis of large-area patterned MoS 2 is considered the principle base for realizing high-performance MoS 2 -based flexible electronic devices. Patterning and transferring MoS 2 films to target flexible substrates, however, require conventional multi-step photolithography patterning and transferring process, despite tremendous progress in the facilitation of practical applications. Herein, an approach to directly synthesize large-scale MoS 2 patterns that combines inkjet printing and thermal annealing is reported. An optimal precursor ink is prepared that can deposit arbitrary patterns on polyimide films. By introducing a gas atmosphere of argon/hydrogen (Ar/H 2 ), thermal treatment at 350 °C enables an in situ decomposition and crystallization in the patterned precursors and, consequently, results in the formation of MoS 2 . Without complicated processes, patterned MoS 2 is obtained directly on polymer substrate, exhibiting superior mechanical flexibility and durability (≈2% variation in resistance over 10,000 bending cycles), as well as excellent chemical stability, which is attributed to the generated continuous and thin microstructures, as well as their strong adhesion with the substrate. As a step further, this approach is employed to manufacture various flexible sensing devices that are insensitive to body motions and moisture, including temperature sensors and biopotential sensing systems for real-time, continuously monitoring skin temperature, electrocardiography, and electromyography signals.
Summary The two-dimensional (2D) transition metal dichalcogenides (TMDs) are promising flexible electronic materials for strategic flexible information devices. Large-area and high-quality patterned materials were usually required by flexible electronics due to the limitation from the process of manufacturing and integration. However, the synthesis of large-area patterned 2D TMDs with high quality is difficult. Here, an efficient and powerful pulsed laser has been developed to synthesize wafer-scale MoS 2 . The flexible strain sensor was fabricated using MoS 2 and showed high performance of low detection limit (0.09%), high gauge factor (1,118), and high stability (1,000 cycles). Besides, we demonstrated its applications in real-time monitoring of health-related physiological signals such as radial artery pressure, respiratory rate, and vocal cord vibration. Our findings suggest that the laser-assisted method is effective and capable of synthesizing wafer-scale 2D TMDs, which opens new opportunities for the next flexible electronic devices and wearable health monitoring.
Elastomers that combined excellent mechanical performance and healability are essential to the advancement of stretchable electronics. However, the strength and toughness of healable elastomers tend to be mutually exclusive. Herein, a new strategy of the dynamic integrated moiety is developed to construct covalent and noncovalent cross-linked polyurethane (CNPU) elastomers. The covalent and noncovalent interactions synergistically enhance the overall mechanical properties of polyurethane elastomers such as tensile strength (48.8 MPa), toughness (282.9 MJ·m–3), stretchability (1740%), and healing efficiency (116%). Finally, elastic conductive wires are fabricated with high load capacity, stable electrical conductivity under static/dynamic stretching, and robust healability to demonstrate the potential use of CNPU elastomers in stretchable electronics.
This work proposes a design, fabrication, and characterization of flexible temperature sensors using temperature-sensitive materials, which are applied using a drop coating method. Temperature-sensitive materials were fabricated by mixing poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) with polyaniline (PEDOT:PSS/PANI). The temperature coefficient of resistance reached −0.803%/°C. Moreover, the detection resolution reached 0.1 °C and had a fast response time of 200 ms. In addition, the sensor can sense spatial temperatures. The sensor has the advantages of low cost, a simple preparation process, and the potential to be used in medical rehabilitation and early disease prevention.
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