An eight-channel triboelectric vibration sensor for azimuth and principal-axis decoding

Purpose This study aims to develop a self-powered triboelectric vibration sensor for continuous sensing of vibration direction under low-frequency excitation. Design/methodology/approach A drum-type triboelectric nanogenerator (DT-TENG) with a symmetric eight-channel structure was developed. Eight-channel peak voltages were normalized into spatial response weights and processed using spatial orthogonal demodulation to obtain azimuthal and axial components. A baseline calibrated for structural symmetry rejected pseudo-angular outputs, while a bilateral activation index characterized response evolution under oblique excitation. Findings The DT-TENG provided repeatable azimuth and principal-axis outputs at both reference and intermediate directions. The mean absolute azimuth error for localized vertical excitation was 2.29° and the mean absolute principal-axis error for in-plane vibration was 2.06°. Under 30°-60° oblique excitation, the response evolved from a localized one-sided pattern toward bilateral axial behavior, while the mean absolute principal-axis error remained 1.50°. Directional decoding also remained comparatively stable under the tested variations in amplitude, frequency, temperature and humidity, as well as under non-periodic excitation. Originality/value The DT-TENG combines self-powered eight-channel spatial sensing with interpretable continuous azimuth and 180°-equivalent principal-axis decoding while enabling qualitative characterization of coupled oblique excitation.