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Graphic abstract:

Currently, four-dimensional (4D) printing programming methods are mainly structure-based, which usually requires more than one material to endow products with site-specific attributes. Here, we propose a new 4D printing programming approach that enables site-specific shape-morphing behaviors in a single material by regulating the printing parameters. Specifically, a direct ink writing three-dimensional (3D) printer with the ability to change printing parameters (e.g., deposition speed) on the fly is reported. By site-specifically adjusting print speed and print path to control the local nematic arrangements of printed liquid crystal elastomers (LCEs), the shape-morphing behaviors of the LCEs can be successfully programmed. In this way, locally programmed popping-up, self-assembling, and oscillating behaviors can be designed by varying the print speed in specific regions. Snake-like curling is realized by uniformly boosting the print speed in a single line. Furthermore, two theories and an ultrasound image diagnostic apparatus are employed to reveal the mechanism behind this behavior. This work provides a feasible way to realize the gradient transition of material properties through a single material. It broadens the design space and pushes the envelope of 4D printing, which is expected to be helpful in the fabrication of soft robotics and flexible electronics.

Programmable nonuniform deformation is of great significance for self-shape-morphing systems that are commonly seen in biological systems and also has practical applications in drug delivery, biomedical devices and robotics, etc. Here, we present a novel gradient four-dimensional (4D) printing method toward biomimetic nonuniform, dual-stimuli self-morphing. By modeling and printing graded active materials with water swelling properties, we can configure continuously smooth gradients of volume fraction of the active material in bilayer structures. The variation of swelling ratio mismatch between the two layers can be delicately regulated, which results in the programmable nonuniform shape transformation. The shape-shifting results can be predicted by the established mathematical model and computational simulations. Furthermore, we demonstrate dual-stimuli self-morphing structures by printing the graded water-responsive elastomer materials onto a heat-shrinkable shape memory polymer, which could produce different shape changes in response to humidity and different temperatures. This method pioneers a versatile approach to broaden the design space for 4D printing and will be compatible with a wide range of active materials meeting various requirements in diverse potential applications.

CyberManufacturing System is an advanced vision for future manufacturing where physical components are fully integrated and seamlessly networked with computational processes, forming an on-demand, intelligent, and communicative manufacturing resource and capability repository with optimal and sustainable manufacturing solutions. The CyberManufacturing System utilizes recent developments in Internet of things, cloud computing, fog computing, service-oriented technologies, among others. Manufacturing resources and capabilities can be encapsulated, registered, and connected to each other directly or through the Internet, thus enabling intelligent behaviors of manufacturing components and systems such as self-awareness, self-prediction, self-optimization, and self-configuration. This research presents an introduction to the CyberManufacturing System, establishing the architecture and functions of the CyberManufacturing System, designing the pivotal control strategy, and investigating the performance analysis of the CyberManufacturing System using modeling and simulation techniques. In total, five component-level examples and one system-level case study have been developed and used for illustration and validation of the CyberManufacturing System operations. The results show that the CyberManufacturing System is superior to other types of manufacturing systems in terms of functionality and cooperative performance.

Fiber is a crucial element in biological micro-structural materials. Replication of fiber-reinforced composites with analogous architectures of their natural counterparts has caused widespread academic concern. Recent researches indicate 3D printing technology has the potential to produce biomimetic structural materials. The aim of this study is to develop a process to fabricate fiber-reinforced composites with ordered yet spatially tunable fiber arrangement. Specifically, we present a method to align fibers during the 3D printing of fiber-reinforced composites. A modified slurry-based stereolithography process was developed, and the fibers in the fiber–resin mixture were aligned by Shear force produced during the spreading of slurry. We investigated the influence of relative factors on fiber orientation, and two models were used to uncover the internal mechanism. By controlling the speed and the direction of the moving blade, the patterns that fibers were arranged can be freely programmed. Therefore, we have extracted bioinspired sinusoidal and zigzag design motifs to analyze their mechanical properties compared with non-bioinspired motifs. The proposed method is relatively material agnostic, more efficient and more facile. It thus provides a promising route to fabricate fiber-reinforced composites, and has potential to be adopted in biological structures researches and industrial applications.

Multi-material additive manufacturing has recently flourished due to its capability to fully exploit the potential of 3D printing for constructing sophisticated heterogeneous material structures. However, producing filaments with tunable internal heterogeneous architecture is difficult in current extrusion-based 3D printing processes. Herein, a novel rotational co-extrusion 3D printing method is proposed that can enable the programmable material configuration of extruded filaments, which is achieved by using a rotatable Y-shape nozzle. By coordinating the rotation and movement of the extrusion nozzle, as well as the air pressure, the material conformation of extruded filaments can be controlled. This strategy can achieve a variety of spatial distribution configurations of heterogeneous materials. In addition, different patterns with customized surface textures have been produced. Furthermore, the 4D printed heterogeneous hydrogels with differential stimuli-responsive properties are demonstrated to generate well-regulated shape-morphing as pre-designed. This method provides an intrinsic ability for 3D printing to construct heterogeneous-filament structures, which have potential applications in the fields of reconfigurable structural materials, tunable meta-materials, tissue engineering, soft robots, etc.

Shape memory polymers with multiple temporary shapes have shown great potential for applications in biomedical, aerospace, and intelligent robotics fields. However, the realization of the multiple shape memory properties of shape memory polymers is currently mostly dependent on formula design. Here, we report a strategy to remotely program the local bending behavior of shape memory composites (SMCs) using an infrared light source. The infrared light source is used to locally activate a single side of the sample with a temporary shape, which induces an asymmetric shape recovery due to the temperature gradient along the thickness direction, and achieves the phototropic response on-demand bending deformation. We exerted control over the bending deformation of the composite prototypes by devising the 3D printing parameters, infrared light intensity, and temporary shape programming. As a demonstration case, we designed and prepared a hand-like structure that can be bent sequentially, a flower whose petals can be excited to fold sequentially, and a digital logic circuit for sequential lighting of LEDs.