Reduced graphene oxide coated thin aluminum film as an optoacoustic transmitter for high pressure and high frequency ultrasound generation

Abstract

We demonstrate that reduced graphene oxide (rGO) coated thin aluminum film is an effective optoacoustic transmitter for generating high pressure and high frequency ultrasound previously unattainable by other techniques. The rGO layer of different thickness is deposited between a 100 nm-thick aluminum film and a glass substrate. Under a pulsed laser excitation, the transmitter generates enhanced optoacoustic pressure of 64 times the aluminum-alone transmitter. A promising optoacoustic wave generation is possible by optimizing thermoelasticity of metal film and thermal conductivity of rGO in the proposed transmitter for laser-induced ultrasound applications.

Generation of planar blast waves using carbon nanotubes-poly-dimethylsiloxane optoacoustic transducer

“…Previous studies tried to replace metals with carbon-based materials to enhance optical absorbance by reducing reflectance, and this approach enhanced the peak pressure to more than one order of magnitude. 18 The analytical solution also shows that the peak pressure increases as the attenuation coefficient of light increases, however, there is a culmination in the peak pressure enhancement. This is because, when the energy of light is sufficiently absorbed by the layer, further increase of attenuation coefficient cannot increase heat generation in the CNT-PDMS film.…”

“…Here, the expression forp γ 2 is equal to that ofp 2 except that q 2 is replaced by γ 2 . And C i,x and C γ 2,f are functions of the reflectance and transmittance of the interface between adjacent materials for acoustic waves (see equation (18) in supplementary material). Multiplication of A i,x andT β i inp i is related to thermal strain of ith material, and multiplication of C i,x and the complex number E i inp i is related to dynamic modulus.…”

A laser ultrasound transducer using carbon nanofibers–polydimethylsiloxane composite thin film

“…16 A two-dimensional gold nanoparticle (AuNP) array with an overlying PDMS layer was adopted to improve the laser ultrasound amplitude ($5 dB) at the frequency range over 50 MHz compared to those using carbon black-PDMS thin films. 17 The carbon-based nanomaterials, including the graphene 18 and the carbon nanotube (CNT) composite, 19 were also considered as the optical absorbing films for laser ultrasound transducers. The reduced graphene oxide coated aluminum film showed the capability of generating acoustic pressure of 7.5 MPa near the transducer surface, which is approximately 64 fold stronger than those using the aluminum thin film alone.…”

Laser-generated ultrasound with optical fibres using functionalised carbon nanotube composite coatings

“…4 Composite media that include distinct elastomeric and absorbing components have emerged as particularly efficient optical transducers. Several absorbers have been considered, including gold nanostructures, 5 carbon black, 6 graphite, 7,8 graphene, 9 and carbon nanotubes (CNTs). 10 The use of polydimethylsiloxane (PDMS) as an elastic component with a large thermal expansion coefficient was highlighted in several studies.…”