RESUMEN
As a technology for polymer surface fabrication, roll-to-roll hot embossing has been widely used because of its advantages, such as its low cost and high efficiency. However, the metal micro-mold is a major factor that determines the hot embossing of the polymer. In this study, a new metal micro-mold manufacturing method is proposed. The metal micro-mold is produced using laser shock imprinting (LSI) on the surface of metal foil. It has the characteristics of good thermal stability and high strength. During our LSI experiment, the strength of the mold increased after laser shocking. In this study, copper foils of different thicknesses were selected for LSI experiments. Through the analysis of the profile and forming depth of the microstructure, combined with the numerical simulation of the forming mechanism of copper foils with different thicknesses using ABAQUS software(Abaqus 2021), a copper foil with a flat back was selected as the final metal micro-mold. On this basis, copper molds with different microstructure shapes were created. Then, the mold was used in the hot-embossing experiment to manufacture the microstructure on the surface of polyethylene terephthalate (PET) and to study the fidelity and integrity of the molded microstructure. The deformation resistance of the copper mold under hot-embossing conditions was verified through a nano-indentation experiment. The final results show that the metal micro-mold produced via LSI had a high accuracy and molding stability and has potential applications in the field of roll-to-roll hot embossing.
RESUMEN
Round-window stimulating transducer is a new solution to treat mixed hearing loss. To uncover the factors affecting the round-window stimulation's performance, we investigated the influence of four main design parameters of round-window stimulating type electromagnetic transducer. Firstly, we constructed a human ear nonlinear lumped parameter model and confirmed its validity by comparing the stapes responses predicted by the model with the experimental data. Following this, an electromagnetic transducer's mechanical model, which simulates the floating mass transducer, was built and coupled to the human ear model; thereby, we established a nonlinear lumped parameter model of implanted human ear under round-window stimulation and verified its reliability. Finally, based on this model, the influences of the four main design parameters, i.e., the excitation voltage, the electromechanical coupling coefficient, the support stiffness, and the preload force, were analyzed. The results show that the change of excitation voltage does not alter the system's natural frequency. Chaotic motion occurs when the electromechanical coupling coefficient is small. Meanwhile, the stapes displacement appears to increase firstly and then decrease with the increase of the electromechanical coupling coefficient. The increase of the support stiffness enlarges the resonance frequency of the stapes displacement and reduces the stapes displacement near the resonance frequency, deteriorating the transducer's hearing compensation at low frequency. The preload force can improve the transducer's hearing compensation performance in mid-high frequency region.
