Magnetically Actuated Composite Vocal Fold Phantom for CT/TA Muscle Mimicry

Abstract

We present a magnetically actuated vocal fold-phantom phonation system capable of reproducing longitudinal tension modulation to mimic cricothyroid (CT) and thyroarytenoid (TA) muscle activation. We first formulate the electromagnetic force model and describe how the resulting artificial muscle activation alters longitudinal stiffness, transverse stiffness, and vibratory behavior. Vocal fold phantoms are fabricated using room temperature vulcanizing (RTV) silicone mixed with Fe powder and cast in 3D-printed molds. Leveraging gravity during curing, Fe powder are concentrated near the transverse surface closest to the actuation coil, enhancing magnetic responsiveness while maintaining tissue-like mechanical properties. Finite-element simulations are used to investigate how longitudinal loading modifies vibratory modes and dynamics. Experimentally, laser Doppler vibrometry (LDV) and knife-edge optical sensing validate the analytical and simulation results. Magnetic actuation enabled longitudinal elongations up to 2.0 mm, providing a tunable phonation frequency range of 127-191 Hz, consistent with simulation. Repeatability testing over 10 hours revealed only +/- 95 & micro;m standard deviation in elongation, demonstrating the reliability and stability of both the actuator and the phantom. These results establish a tunable, muscle-mimicking platform that can facilitate controlled investigations of tension-dependent phonatory mechanics and support future laryngological research.