High Aspect Ratio Asymmetric Microridge Structure Arrays Fabrication for Anisotropic Triboelectric Nanogenerator

Femtosecond laser has been widely used in micro- and nanodevice manufacturing and functional interface construction due to its ultrafine processing capability. However, the controllable fabrication of anisotropic micro–nano structures with high structural fidelity remains challenging. In this study, a tilted-sample autofocusing femtosecond laser direct writing method combined with a replication process is proposed to fabricate asymmetric micro–nano structure arrays. By precisely adjusting the processing angle of silicon substrates, ridge-shaped trench arrays with inclination angles of 0°, 10°, and 20°, and an aspect ratio of up to 5:1 were successfully constructed. Subsequently, a polydimethylsiloxane (PDMS) replication process was employed to obtain flexible asymmetric microridge structure layers with high morphological integrity and excellent replication fidelity. Based on the fabricated asymmetric micro–nano structure arrays, a sliding triboelectric nanogenerator (S-TENG) with anisotropic electrical characteristics was developed. The triboelectric output performance of structures with different inclination angles was systematically investigated. The results demonstrate that the peak output voltage of the S-TENG with a 20° inclined structure is approximately 120% higher than that of the 0° structure, indicating a significantly enhanced triboelectric output under identical testing conditions. Moreover, the S-TENG based on asymmetric microridge structures exhibits pronounced anisotropic response characteristics. The proposed fabrication strategy features good scalability and process compatibility, providing a reliable route for the development of anisotropic flexible triboelectric sensors and expanding their potential applications in multidimensional force sensing fields, such as intelligent prosthetics and humanoid robotics.