Acoustical characterisation of carbon nanotube-loaded polydimethylsiloxane used for optical ultrasound generation

Alles, Erwin J.; Heo, Jeongmin; Noimark, Sacha; Colchester, Richard J.; Parkin, Ivan P.; Baac, Hyoung Won; Desjardins, Adrien E.

doi:10.1109/ultsym.2017.8092343

Cited by 7 publications

(9 citation statements)

References 18 publications

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“…The CNT-PDMS film exhibits low frequency dependent attenuation over the majority of the frequency range relevant to the current study; e.g. a 100 μm film attenuates frequencies up to 22 MHz by less than 1.7dB [13]. The attenuation of the photoacoustic wave as it propagates through the CNT-PDMS film is thus negligible.…”

Section: A Optical Ultrasound Generationmentioning

confidence: 89%

Broadband All-Optical Plane-Wave Ultrasound Imaging System Based on a Fabry–Perot Scanner

Pham

Noimark

Huynh

et al. 2021

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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A broadband all-optical plane-wave ultrasound imaging system for high-resolution 3D imaging of biological tissues is presented. The system is based on the planar Fabry-Perot (FP) scanner for ultrasound detection and the photoacoustic generation of ultrasound in a Carbon-Nanotube-Polydimethylsiloxane (CNT-PDMS) composite film. The FP sensor head was coated with the CNT-PDMS film to act as an ultrasound transmitting layer for pulse-echo imaging. Exciting the CNT-PDMS coating with nanosecond laser pulses generated monopolar plane-wave ultrasound pulses with MPa-range peak pressures, and a-6dB bandwidth of 22 MHz, that were transmitted into the target. The resulting scattered acoustic field was detected across a 15 mm × 15 mm scan area with a step size of 100 and an optically defined element size of 64. The-3dB bandwidth of the sensor was 30 MHz. A 3D image of the scatterer distribution was then recovered using a k-space reconstruction algorithm. To obtain a measure of spatial resolution, the instrument line-spread function (LSF) was measured as a function of position. At the centre of the scan area the depth dependent lateral LSF ranged from 46 to 65 for depths between 1 and 12 mm. The vertical LSF was independent of position and measured to be 44 over the entire field of view. To demonstrate the ability of the system to provide high-resolution 3D images, phantoms with well-defined scattering structures of arbitrary geometry were imaged. To demonstrate its suitability for imaging biological tissues, phantoms with similar impedance mismatches, sound speed and scattering properties to those present in tissue, and ex-vivo tissue samples were imaged. Compared to conventional piezoelectric based ultrasound scanners this approach offers the potential for improved image quality and higher resolution for superficial tissue imaging. Since the FP scanner is capable of high-resolution 3D photoacoustic imaging of in-vivo biological tissues, the system could ultimately be developed into an instrument for dual-mode all-optical ultrasound and photoacoustic imaging.

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Section: A Optical Ultrasound Generationmentioning

confidence: 89%

Broadband All-Optical Plane-Wave Ultrasound Imaging System Based on a Fabry–Perot Scanner

Pham

Noimark

Huynh

et al. 2021

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…The lower sound pressure at the 0.9 µm thin sample was caused by the fact that more transmission of the laser beam takes place, in this case a thin layer emits higher frequencies ultrasonic waves. [ 11,18,61 ] The relation of layer thicknesses with frequency ranges can be showed with the 32.2 µm thick sample, where the spectrum of 6.7 MHz differs significantly from the others ranging from 9.0 up to 9.7 MHz. [ 11,18,61 ] The sound pressure measured with the 32.2 µm thick layer (Figure 8b) is not significantly higher (3.2 MPa), since the attenuation of the ultrasound pressure in thicker layers becomes stronger than within thinner layers.…”

Section: Ultrasound Pressure Measurementsmentioning

confidence: 99%

“…[ 11,18,61 ] The relation of layer thicknesses with frequency ranges can be showed with the 32.2 µm thick sample, where the spectrum of 6.7 MHz differs significantly from the others ranging from 9.0 up to 9.7 MHz. [ 11,18,61 ] The sound pressure measured with the 32.2 µm thick layer (Figure 8b) is not significantly higher (3.2 MPa), since the attenuation of the ultrasound pressure in thicker layers becomes stronger than within thinner layers. [ 18 ] Poduval et al observed and describes similar effects, which explain the lower sound pressures at 0.9 and 32.2 µm.…”

Section: Ultrasound Pressure Measurementsmentioning

confidence: 99%

Synthesis and Characterization of CNT Composites for Laser‐Generated Ultrasonic Waves

Oser

Düttmann

Schmid

et al. 2020

Macro Materials & Eng

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In the last few years, extensive progress in ultrasonic wave generation by using multiwalled carbon nanotubes (MWCNTs) in combination with polydimethylsiloxane (PDMS), functional composites, has been achieved. Due to high optical absorption of MWCNTs as perfect absorbers for laser beams and the high thermal expansion coefficient of PDMS, a compact transducer for ultrasonic wave generation at higher frequency can be realized. This study reports a novel method to synthesize MWCNT-PDMS composites deposited on a glass substrate by spray coating, which is done in a short time of 2 h. The layers (0.9-32.2 µm) show low optical transmission properties of 13.9-0.0% at a wavelength of 1047 nm. Apart from using a 1% Triton-X-100 stock solution and then diluted to a 0.1% relatively nonhazardous solution, no toxic chemicals are used. The Triton-X-100 solution is not hazardous for lab handling and is a commonly used lab detergent for the treatment of biological cells. The achieved sound pressure level is 3.4 MPa with a frequency bandwidth of 9.7 MHz. These results show the potential for a fast and nontoxic production of laser-generated ultrasonic transducers, which can be used well in the field of nondestructive material testing of layered materials or in medicine with an appropriate frequency range.

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“…The bandwidth of this wave depends on the temporal characteristics of the excitation light. In general, the bandwidth can be increased by decreasing the duration of excitation light pulses; however, in practice, these increases are limited by frequency-dependent ultrasound attenuation within the coating ( 10 ) and within blood and vascular tissue ( 11 ). To achieve efficient optical-US transduction, a material with a high optical absorption coefficient and a high thermal expansion coefficient is desirable.…”

Section: Introductionmentioning

confidence: 99%

“…These high pressures enable high imaging penetration depths, and the broad bandwidths give rise to high axial resolution. A small coating thickness can be important to minimize acoustic attenuation within nanocomposite materials ( 10 ). To this end, several methods have been explored for depositing nanocomposite materials onto the distal surface of the fiber optic transducer, including spin-coating ( 17 ), electrospinning ( 18 ), and dip-coating ( 15 ).…”

Section: Introductionmentioning

confidence: 99%

Optically Generated Ultrasound for Intracoronary Imaging

Little

Colchester

Noimark

et al. 2020

Front. Cardiovasc. Med.

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Conventional intravascular ultrasound (IVUS) devices use piezoelectric transducers to electrically generate and receive US. With this paradigm, there are numerous challenges that restrict improvements in image quality. First, with miniaturization of the transducers to reduce device size, it can be challenging to achieve the sensitivities and bandwidths required for large tissue penetration depths and high spatial resolution. Second, complexities associated with manufacturing miniaturized electronic transducers can have significant cost implications. Third, with increasing interest in molecular characterization of tissue in-vivo , it has been challenging to incorporate optical elements for multimodality imaging with photoacoustics (PA) or near-infrared spectroscopy (NIRS) whilst maintaining the lateral dimensions suitable for intracoronary imaging. Optical Ultrasound (OpUS) is a new paradigm for intracoronary imaging. US is generated at the surface of a fiber optic transducer via the photoacoustic effect. Pulsed or modulated light is absorbed in an engineered coating on the fiber surface and converted to thermal energy. The subsequent temperature rise leads to a pressure rise within the coating, which results in a propagating ultrasound wave. US reflections from imaged structures are received with optical interferometry. With OpUS, high bandwidths (31.5 MHz) and pressures (21.5 MPa) have enabled imaging with axial resolutions better than 50 μm and at depths >20 mm. These values challenge those of conventional 40 MHz IVUS technology and show great potential for future clinical application. Recently developed nanocomposite coating materials, that are highly transmissive at light wavelengths used for PA and NIRS light, can facilitate multimodality imaging, thereby enabling molecular characterization.

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Acoustical characterisation of carbon nanotube-loaded polydimethylsiloxane used for optical ultrasound generation

Cited by 7 publications

References 18 publications

Broadband All-Optical Plane-Wave Ultrasound Imaging System Based on a Fabry–Perot Scanner

Broadband All-Optical Plane-Wave Ultrasound Imaging System Based on a Fabry–Perot Scanner

Synthesis and Characterization of CNT Composites for Laser‐Generated Ultrasonic Waves

Optically Generated Ultrasound for Intracoronary Imaging

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