This article reviews soft pneumatic actuators (SPAs) that are manufactured entirely via additive manufacturing methods. These actuators are known as four-dimensional (4D)-printed SPAs and can generate bending motions in response to either pressurised or vacuum (negative pressure) air stimulus after fabrication. They are characterised by geometrical and material factors that determine their motion trajectory, and the force they exert on manipulated soft objects in delicate applications such as food handling and non-invasive surgery. Here, we review various 3D printers and materials used for the fabrication of the pressurised air bending-type SPAs. The reported approaches for modelling and control of these actuators are presented and compared. General discussions, as well as future directions and challenges of these actuators, are given.

Building on the recent progress of four-dimensional (4D) printing to produce dynamic structures, this study aimed to bring this technology to the next level by introducing control-based 4D printing to develop adaptive 4D-printed systems with highly versatile multi-disciplinary applications, including medicine, in the form of assisted soft robots, smart textiles as wearable electronics and other industries such as agriculture and microfluidics. This study introduced and analysed adaptive 4D-printed systems with an advanced manufacturing approach for developing stimuli-responsive constructs that organically adapted to environmental dynamic situations and uncertainties as nature does. The adaptive 4D-printed systems incorporated synergic integration of three-dimensional (3D)-printed sensors into 4D-printing and control units, which could be assembled and programmed to transform their shapes based on the assigned tasks and environmental stimuli. This paper demonstrates the adaptivity of these systems via a combination of proprioceptive sensory feedback, modeling and controllers, as well as the challenges and future opportunities they present.

Triboelectric nanogenerator (TENG) development is undergoing rapid progress utilizing the state‐of‐the‐art 3D‐printing technologies. Herein a critical analysis of the latest developments in 3D‐printed wearable and implantable TENGs that can be used to energize small portable electronic and biomedical devices is presented. Recent progress in 3D‐printed triboelectric nanogenerator (3DP‐TENG) materials and architectural formations, as well as their performance, is evaluated for powering systems that implement physiological monitoring, multifunctional sensing, electronic energizing, noise canceling, dust filtering, and self‐healing. Furthermore, the review explicitly focuses on the 3D‐printing approaches used to form stable and robust 3DP‐TENGs. In addition, the key challenges to improving the performance of 3DP‐TENGs for optimal energy harvesting are discussed, and a roadmap is given for research and translation to commercial markets in the next decade.