External-field-assisted additive manufacturing for micro/nano device fabrication

Micro/nano devices (MNDs) are characterized by miniaturization, high precision, and multifunctional integration, making them highly suitable for use in areas such as microrobotics, biomedical devices and electronic sensors. Their fabrication requires exceptional precision in structural integrity, material control, and functional integration. Traditional micro/nano fabrication techniques face inherent limitations in constructing complex three-dimensional (3D) architectures and integrating multiple materials. While additive manufacturing (AM) provides flexibility, challenges remain in material alignment control, microstructural organization, and multifunctional integration. To overcome these limitations, field-assisted additive manufacturing (FAM) has emerged as a promising approach that combines magnetic, acoustic, or electric fields to regulate material alignment, microstructural organization, and spatial alignment. This capability improves fabrication precision, enhances material anisotropy and facilitates functional integration. This review systematically explores the mechanisms, fabrication process, and functional integration of FAM in the framework of nozzle-based and vat photopolymerization-based, while further exploring their applications in microrobotics, biomedical devices, and electronic sensors. Moreover, this review provides a comparative overview of different FAM approaches, highlighting their respective characteristics, typical applications, and unique advantages. In addition, the major challenges facing FAM research are comprehensively assessed and future directions are explored, including advances in spatial precision control capability, intelligent control for process integration, and multi-field coupling optimization. This review establishes a foundational theoretical framework that can serve as a systematic reference for micro/nano manufacturing researchers to promote the development of FAM for high-performance micro/nano device fabrication.