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.

Integrated sensor–actuators with exciting functionalities, such as action self‐sensing, position self‐sensing, posture self‐sensing, or active sensing, are promising for applications in biomedical device, human–machine interaction, intelligent self‐protection devices, and humanoid robots. Despite recent progress, it remains challenging to achieve a macroscopical integrated sensor–actuator in a material system with microstructures. To address this critical challenge, a 4D printing bioinspired microstructure strategy is reported to design a high‐performance integrated sensor–actuator capable of simultaneous actuation and sensation. Decoupled thermal stimulation and strain sensation is achieved by combining nanocarbon black/polylactic acid composites with bioinspired gradient microgap structures. As a result, printed integrated sensor–actuators can actively touch objects triggered by thermal stimulation and self‐sense the touching state through the resistance change. It is anticipated that the basic design principle underlying this behavior can be used to develop integrated sensor–actuators of various shapes and functionalities to meet desirable applications.

The advent of electrochromic aqueous batteries represents a promising trend in the development of smart and environmentally friendly energy storage devices. However, it remains a great challenge to integrate electrochromic, flexible, and patterned features into a single battery unit through a simple operation. Herein, an entirely new class of hetero-polyacid-based underwater adhesives is designed and synthesized by combining the redox properties of hetero-polyacids and the water-resistant binding of adhesives in single system. The hybrid underwater adhesives not only serve as printable electrode coatings in aqueous solution but also offer unique electrochromic feature for guiding the convenient fabrication of self-powered electrochromic aqueous battery. The reversible discharging and H 2 O 2 assistant charging behavior is also demonstrated. This kind of wet and electrochromic adhesive with excellent toleration of mechanical deformation offers great promise in developing flexible and smart energy storage configuration, which provides a user-device interface platform allowing one to evaluate the battery's charging state based on the naked eye-visible change in color.

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An emerging technology for producing programmable stimuli‐response materials, 4D printing, is currently confined to shape changing. A new type of 4D printing technology that produces shape–color double‐responsive materials similar to those ubiquitous in biomaterials systems, such as octopuses simultaneously altering their skin color and shape in response to environmental stimuli, is presented. Shape–color double‐responsive composites are prepared through the incorporation of shape‐memory polymer (polylactic acid) and thermochromic pigments. Using the prepared composites and a fused deposition modeling 3D printer, shape–color double‐responsive 4D printing is achieved. The influence of the process parameters and stimulus methods on the characteristics of 4D deformation and discoloration is investigated. Furthermore, by regulating the geometry, process parameters, and stimulus conditions, the speed of shape changing and color transition can be controlled simultaneously. Finally, as a proof‐of‐concept, biomimetic soft robots with shape–color dual responses, including a color‐shifting blooming flower and a camouflaging octopus, are demonstrated. Compared with previously reported 4D printing technologies, this research offers a facile method for manufacturing multiresponsive active composites. The developed shape–color double‐responsive 4D printing method is expected to be helpful for exploring the full potential of 4D printing.