Broadband Spectroscopic Thermoacoustic Characterization of Single-Walled Carbon Nanotubes

Abstract

Carbon nanotubes have attracted interest as contrast agents for biomedical imaging because they strongly absorb electromagnetic radiation in the optical and microwave regions. This study applies thermoacoustic (TA) imaging and spectroscopy to measure the frequency-dependent absorption profile of single-walled carbon nanotubes (SWNT) in the ranges of 2.7–3.1 GHz and 7–9 GHz using two tunable microwave sources. Between 7 and 9 GHz, the peak TA signal for solutions containing semiconducting and metallic SWNTs increased monotonically with a slope of 1.75 AU/GHz (R2=0.95) and 2.8 AU/GHz (R2=0.93), respectively, relative to a water baseline. However, after compensating for the background signal from water, it was revealed that the TA signal from metallic SWNTs increased exponentially within this frequency band. Results suggest that TA imaging and spectroscopy could be a powerful tool for quantifying the absorption properties of SWNTs and optimizing their performance as contrast agents for imaging or heat sources for thermal therapy.

Advanced optoacoustic methods for multiscale imaging of in vivo dynamics

“…Single-walled carbon nanotubes (SWNT) are the most widespread carbon NPs [183–185], with diameters of 1–3 nm and variable lengths, from nanometers to millimetres or even centimetres. They absorb light over a very broad spectrum and are also able to provide thermoacoustic contrast for electromagnetic waves in the GHz range [186], although the per-particle optoacoustic signal strength is lower in SWNT than in gold NPs (Fig. 9b).…”

Analysis of Transient Thermoacoustic Characteristics and Performance in Carbon Nanotube Sponge Underwater Transducers

“…In recent days, a type of newly developed nanomaterial transducer [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] offers a promising solution by using the thermoacoustic (TA) effect [29]. TA transducers made of those nanomaterials operate by exchanging the produced Joule heating to the surrounding fluid and generating acoustic waves.…”

Design and characteristic analysis of flexible CNT film patch for potential application in ultrasonic therapy

“…Nowadays, with the rapid development of nanotechnology, a kind of nanomaterials having excellent thermoacoustic (TA) effects were fabricated and applied to design TA ultrasonic transducers, such as nanocrystalline silicon [5], CNT film [6][7][8], metal nanowires [9][10][11][12], indium tin oxide film [13,14], graphene film [15] [16][17][18][19][20][21], MXenes [22], graphene foam [23][24][25][26] and CNT sponge [27,28]. When an AC signal is passing through the TA nanomaterials, a thermal gradient is generated within the material due to the effect of Joule heating.…”