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Silicone rubber elastomers are broadly used in various fields, where the three-dimensional (3D) printing of silicone rubber elastomers is important for the free construction of complex structures. Herein, a series of polydimethylsiloxane/polytetrafluoroethylene composite inks for direct-ink-writing 3D printing are developed. The inks are prepared by directly mixing a silicone rubber liquid precursor with polytetrafluoroethylene micropowder. The polytetrafluoroethylene micropowder serves as a thixotropic agent to regulate the rheological properties of the polydimethylsiloxane precursor to fulfill the requirement of 3D printing and endow the composite material with high electron affinity. The printed polydimethylsiloxane/polytetrafluoroethylene composite elastomer exhibits excellent elasticity and cyclic stability. A high-performance triboelectric nanogenerator is constructed with the 3D-printed polydimethylsiloxane/polytetrafluoroethylene composite as the triboelectric layer and elastic structure. This work establishes a new method of 3D printing polydimethylsiloxane-based elastomers and thus provides a new technique for constructing complex structures in flexible devices.

Polyaniline gels with a three-dimensional network structure are attractive for their broad application prospects in flexible and stretchable electric devices. In this paper, we develop a facile solution assembly method to prepare an elastic polyaniline/poly(vinyl alcohol) composite organogel and a hydrogel. The polyaniline and poly(vinyl alcohol) chains gelate from the homogeneous mixed solution in N-methyl-2-pyrrolidone via crystallization of poly(vinyl alcohol), producing a uniform organogel with hydrogen bonds between two polymers, and the organogel can be further converted into a hydrogel by solvent exchange. The composite gels exhibit excellent mechanical properties, which make them one of the best materials for additive manufacture, such as molding and 3D printing. This study develops an efficient method to fabricate polyaniline gels with good processability and multifunctions.

Prompt and accurate measurement of the three-dimensional (3D) contours of complex surfaces is currently a key research direction. In the current study, we presented a fast grayscale stripe synthesis method based on focused binary patterns. Specifically, by encoding a group of binary patterns, the patterns were captured by the camera within one exposure time cycle and synthesized into a grayscale-intensity triangular wave stripe pattern. Importantly, this method utilized the fast projection rate of the binary pattern, improved the speed of stripe projection, and prevented nonlinearity in the 3D measurement of stripe projection by synthesizing the gray pattern in the form of a binary pattern.

E-textiles are of great significance for next-generation wearable electronics. However, the current smart textiles generally have shortcomings such as intricate preparation processes and redundant structure. Here, we have developed a 3D printing method to prepare stretchable elastic fibers with a coaxial core-sheath structure, which consists of conductive core and insulative sheath. The addition of graphene and PTFE particles successfully manipulates the rheological behavior of the PDMS prepolymer and makes it suitable for 3D printing of core-sheath coaxial stretchable fibers. Furthermore, the large-scale and customized manufacturing of stretchable smart textiles has been achieved. Based on triboelectric effect, the core-sheath elastic fiber can perform the function of wearble tactile sensing as e-skin and the smart textile demonstrates the ability of matrix tactile sensing through the interlaced structure of warp and weft. Moreover, the smart textile has many advantages such as washability, breathability, super stretchability and robustness, making it promising for wearable electronics.

Three-dimensional (3D) shape measurement of fringe projection profilometry (FPP) with high speed and accuracy is required in many applications. The measurement speed of FPP system is mainly limited by the low frame rate of pattern projection. Although defocusing binary patterns can be used to increase the measurement speed greatly, it will decrease the measurement depth. To this end, a novel triangular pattern generation method is proposed in this paper. By designing and projecting binary strip patterns with focused projector, images of triangular patterns can be then acquired with high frame rate. Fast and accurate 3D shape measurement can be finally obtained by using phase-shifting triangular patterns. Compared with the traditional sinusoidal patterns, the proposed method can improve the projection rate more than 4 times. Moreover, the proposed method will not decrease the measurement depth. Experimental results are given to confirm the validity of the proposed method.

In the fields of satellite formation, large-scale manufacturing, and ultra-precision machining, high-precision ranging based on the femtosecond laser is one of the necessary technologies. However, the fluctuations of the air refractive index and the limited tuning range of repetition rate restrict the measurement precision and range. Using only one femtosecond comb that corrects the air refractive index simultaneously, a method for ranging without the dead zone of measurement is described. A delay optical path is established in the ranging system to eliminate the dead zone of measurement by a comb. Meanwhile, in order to ensure the consistency of the pulse sequence between the fundamental frequency beam and the second-harmonic beam after the delay optical path, the second-harmonic beam generates on the delay optical path after the fundamental harmonic passes the long fiber. A two-color method is used to correct the effect of the air refractive index. The experimental result demonstrates the measurement precision of 7.2 µm at ∼ 0.8 m with correction of the air refractive index, and the precision of measurement is 8.4 µm at ∼ 2.2 m . Finally, the maximum deviation between our system and the reference standard is 5.0 µm.