Gap separation effect on thermoacoustic wave generation by heated suspended CNT nano-thinfilm

Abstract

Completely suspended nano-thinfilms (NTFs) can be fabricated by drawing carbon nanotube (CNT) arrays in an open space. These NTFs have been identified as an excellent source for generating powerful thermoacoustic waves. However, NTFs are widely known to be structurally weak and that vulnerable structural stability poses a great threat and challenge to their applications in practical devices. By suspending NTFs on a substrate, the structural stability can be significantly reinforced. In this paper, an analytical model for the thermoacoustic pressure response of suspended NTFs, which are fabricated by suspending a nano-thinfilm on a substrate, is established and the model is validated by comparing with experiment. The influence of gap separation between thinfilm and substrate on the acoustic pressure response can be analyzed using the analytical model. By comparing with completely suspended NTFs in an open space, the performance of a suspended-on-substrate NTF is far more efficient if the gap separation is within a few micrometers. In addition, the new analytical model developed here also reports the acoustic pressure response in different surrounding gaseous media. The effect of substrate thermal properties on the performance of such suspended NTF devices is also analyzed theoretically. In general, the analytical model is expected to provide effective guidelines for further design optimization analysis using such thermoacoustic devices.