Vibroacoustic Characteristics of a Specific Patterned Polymer with Graphene for an Electrostatic Speaker

Abstract

Graphene/polymer actuators were developed using bilayer graphene and various polymer substrates for use as transparent, flexible, and robust electrostatic speaker units. Additionally, a resonant frequency shift was induced using a polymer substrate on which various micropatterns were transferred to boost bass. The total sound pressure level (SPL) in the graphene/polymer actuator was measured by a sweep, and the frequency of the spectrum was confirmed to be one-third that of the octave band frequency. The change in the vibroacoustic characteristic with changes in Young's modulus and density was studied for the polymers of the same size and thickness. Particularly, the possibility of boosting bass was confirmed by inducing a resonant frequency shift and increasing the total SPL by adding micropatterns on a polymer substrate under the same conditions. The resonance frequency of 523 Hz and the SPL of 54 dBA in flat polymer film became 296 Hz and 69 dBA in a specific pattern, which produced a sound of >15 dB based on the same flat polymer. We expect that the design and information provided herein can provide the key parameters required to change the resonant frequency in small-size devices for the application of graphene/polymer thin-film actuators.

A Review of Acoustic Devices Based on Suspended 2D Materials and Their Composites

“…Reproduced with permission. [131] Copyright 2023, American Chemical Society. performance index (MPI, which is proportional to the loss coefficient and positively correlated with the elastic modulus, reflecting the acoustic properties of the material) was between 0.11-0.19 m 4 kg −1 s −2 , considerably higher than that of the traditional diaphragms (with MPI around 0.01-0.05 m 4 kg −1 s −2 ), which is believed to be caused by the interlayer friction and cross-linking strengthening within X-GO structure.…”

“…Lee et al synthesized different GPC materials to investigate this phenomenon, aiming to explore approaches to improve the low-frequency performance of the speaker. [131] First, they calculated the resonant frequency of the diaphragm, which is mainly influenced by parameters such as polymer composition thickness, Young's modulus and surface stress of the di-aphragm of GPC, etc. This can be approximately expressed as follows,…”

“…synthesized different GPC materials to investigate this phenomenon, aiming to explore approaches to improve the low‐frequency performance of the speaker. [ 131 ] First, they calculated the resonant frequency of the diaphragm, which is mainly influenced by parameters such as polymer composition thickness, Young's modulus and surface stress of the diaphragm of GPC, etc. This can be approximately expressed as follows, $$$$\begin{equation}{f_{{\mathrm{mn}}}} = \frac{{\beta _{{\mathrm{mn}}}^2}}{{2{{\pi}}{a^2}}}\ \sqrt {\frac{{E{t^2}}}{{12{\rho _{\mathrm{m}}}\left( {1 - {v^2}} \right)}}} \end{equation}$$$$where N is graphene's layer number, β mn is the modified Bessel function, ρ m is the diaphragm's mass density, t is the diaphragm's thickness, v is Poisson's ratio and E is the diaphragm's Young's modulus.…”

“…Increase in SPL and change of resonant peak can be controlled by selection of micro-decoration patterns. Reproduced with permission [131]. Copyright 2023, American Chemical Society.…”

Enhancing OLED emitter efficiency through increased rigidity

“…Donors of different chromophores, such as benzofurocarbazole and benzothienocarbazole, which are obtained by fusing carbazole with benzofuran or benzothiophene, have also been developed. 4–6 Recently, materials with improved rigidity, based on the v -DABNA backbone and known as HF materials, have been reported. 7,8 The second key principle involves conferring bipolar characteristics to maintain charge balance.…”