Graphene Earphones: Entertainment for Both Humans and Animals

Abstract

The human hearing range is from 20 Hz to 20 kHz. However, many animals can hear much higher sound frequencies. Dolphins, especially, have a hearing range up to 300 kHz. To our knowledge, there is no data of a reported wide-band sound frequency earphone to satisfy both humans and animals. Here, we show that graphene earphones, packaged into commercial earphone casings can play sounds ranging from 100 Hz to 50 kHz. By using a one-step laser scribing technology, wafer-scale flexible graphene earphones can be obtained in 25 min. Compared with a normal commercial earphone, the graphene earphone has a wider frequency response (100 Hz to 50 kHz) and a three times lower fluctuation (±10 dB). A nonlinear effect exists in the graphene-generated sound frequency spectrum. This effect could be explained by the DC bias added to the input sine waves which may induce higher harmonics. Our numerical calculations show that the sound frequency emitted by graphene could reach up to 1 MHz. In addition, we have demonstrated that a dog wearing a graphene earphone could also be trained and controlled by 35 kHz sound waves. Our results show that graphene could be widely used to produce earphones for both humans and animals.

Influence of thermodynamic properties of a thermo-acoustic emitter on the efficiency of thermal airborne ultrasound generation

“…A further experimental confirmation of the EDF-model in a frequency range up to 50 kHz can be found in the recently published work by Tian et al [31] who used the EDF-model to predict sound pressures for a graphene-based TA-emitter layered on a polyethylene terephthalate (PET) substrate. The authors report a deviation of less than 2 dB between the theoretical EDF-prediction and the experimental results.…”

Human‐Like Sensing and Reflexes of Graphene‐Based Films

“…It was found that graphene has a significant flat frequency response in the wide ultrasound range ≈20–50 kHz. Additionally, graphene exhibits ultra‐small heat capacity per unit area (HCPUA), more efficiently converting joule heating to sound waves 94, 95, 96, 97, 98, 99, 100. It has been also reported that single‐layer graphene (SLG) presents the lowest HCPUA,101 demonstrating more efficient than other materials.…”

“…Since then, Ren et al developed a high‐efficiency route for the fabrication of real graphene earphones using laser‐scribed graphene (LSG) 98. As is shown in Figure 9 a, the ultrafast graphene growth was obtained at precise locations by a mask‐free and programmable laser scribing technology.…”

“…f) The testing of graphene earphones on the dog. Reproduced with permission 98. Copyright 2011, American Chemical Society.…”

Theory and modeling of cylindrical thermo-acoustic transduction

“…Subsequently, a series of thermo-acoustic transductions manufactured from different materials such as CNT assemblies [9], aluminum wires array [10,11], graphene [12], silver nanowires film [13], suspended CNT-yarn array on a substrate [14] and individual CNT [15,16], were successively reported. A practical wideband sound frequency graphene earphone was also designed and tested by Tian et al [17]. In addition to the intensively experimental research, a few theoretical studies on thermo-acoustics were also reported, including the modeling of thin-film located on a substrate [18], the CNT * Corresponding author.…”