碳纳米管薄膜是一种由碳原子组成的新型纳米材料,可被制作成一种基于热致发声效应的扬声器。针对碳纳米管薄膜电-热-声系统的频率失真问题,提出添加钳位电路的解决方法,并进行了理论研究和实验验证。结果表明,加入钳位电路后,系统输出的声波频率与输入电压频率变为一致,且声能量显著增大,声压级提高约5 d B。与传统叠加直流偏置电压的方法相比,无需直流电源,降低了系统功耗。
Based on thermoacoustic theory, a coupled thermal-mechanical model for graphene films is established, and the analytical solutions for thermal-acoustic radiation from a graphene thin film are obtained. The sound pressure of the graphene film generator on different substrates is measured, and the measurement data is compared with the theoretical results. The frequency response from the experimental results is consistent with the theoretical ones, while the measured values are slightly lower than the theoretical ones. Therefore, the accuracy of the proposed theoretical model is verified. It is shown that thermal-acoustic radiation from a graphene thin film reveals a wide frequency response. The sound pressure level increases with the frequency in the low frequency range, while the sound pressure varies smoothly with frequency in the high frequency range. Thus it can be used as excellent thermal generator. When the thermal effusivity of the substrate is smaller, then the sound pressure of grapheme films will be higher. Furthermore, the sound pressure decreases with the increase of heat capacity per unit area of grapheme films. Results will contribute to the mechanism of graphene films generator and its applications in the design of loudspeaker and other related areas.
