Theory and modeling of multi-layer carbon nanotube thin film thermoacoustic transducer

A new model for a multi-layer thermoacoustic transducer that takes full advantage of the excellent the thermoacoustic characteristics of carbon nanotube (CNT) thin film is developed. Analytical exact solutions of acoustic pressure distribution for both near and far fields are presented with engineering interpretation. By assuming acoustically transparent stacking layers and a total thickness less than a tenth of the sound wavelength, the acoustic pressure field relations between parallel layers are established that subsequently yield the sound pressure for the overall stacking films. A comparison between theoretical prediction and experiment for single-layer and multi-layer CNT thin films is presented and excellent agreement is reported. Key influencing factors including the total layer number, and the spacing between separated films and gas medium on the sound pressures level (SPL) are investigated and discussed in detail. Some design criteria that increases the SPL of the multi-layer CNT thin film transducer are also established.