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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - A Miniature Fiber-Optic Photoacoustic Probe Coated with MoS<inf>2</inf>-PDMS for Water Level and Oil-Water Interface Detection*
摘要： We demonstrate a miniature broadband (~13.3 MHz) fiber-tip photoacoustic probe with ~68.32-μm thick MoS2-polydimethylsiloxane (PDMS) composite for accurate measurement of water and oil-water interface levels. The composite was applied to the tip of a double-clad fiber with an outer diameter of 125 μm using dip coating. The propagation time of an ultrasonic wave generated by a 5-ns pulsed laser excitation in liquids was extracted to determine water level or silicone oil-water interface in a glass tube. An excellent goodness of fit (R2≈0.996) was achieved with a high accuracy of ~1.5 μm in the tested water-level range of 0-218 μm. Then the proposed technique exhibited an average relative error of 0.68% for the oil-water interface detection, along with a good fitting coefficient of 98.7% in the range of 0-8 mm. The presented photoacoustic probe therefore shows a great potential in compact accurate liquid level monitoring.
关键词： photoacoustic probe,2D nanomaterials,optical fiber tip,ultrasonic liquid level measurement
更新于2025-09-19 17:15:36
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Bioinspired magnetic nanoparticles as multimodal photoacoustic, photothermal and photomechanical contrast agents
摘要： Nanoparticles from magnetotactic bacteria have been used in conventional imaging, drug delivery, and magnetic manipulations. Here, we show that these natural nanoparticles and their bioinspired hybrids with near-infrared gold nanorods and folic acid can serve as molecular high-contrast photoacoustic probes for single-cell diagnostics and as photothermal agents for single-cell therapy using laser-induced vapor nanobubbles and magnetic field as significant signal and therapy amplifiers. These theranostics agents enable the detection and photomechanical killing of triple negative breast cancer cells that are resistant to conventional chemotherapy, with just one or a few low-energy laser pulses. In studies in vivo, we discovered that circulating tumor cells labeled with the nanohybrids generate transient ultrasharp photoacoustic resonances directly in the bloodstream as the basis for new super-resolution photoacoustic flow cytometry in vivo. These properties make natural and bioinspired magnetic nanoparticles promising biocompatible, multimodal, high-contrast, and clinically relevant cellular probes for many in vitro and in vivo biomedical applications.
关键词： theranostics,super-resolution,contrast agents,photomechanical,photoacoustic,magnetic nanoparticles,photothermal,circulating tumor cells,bioinspired,magnetotactic bacteria
更新于2025-09-19 17:15:36
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Optical coherence tomography angiography and photoacoustic imaging in dermatology
摘要： Optical coherence tomography angiography (OCTA) is a relatively novel functional extension of the widely accepted ophthalmic imaging tool named optical coherence tomography (OCT). Since OCTA’s debut in ophthalmology, researchers have also been trying to expand its translational application into dermatology. The ability of OCTA in resolving microvasculature has shown promising results in imaging skin diseases. Meanwhile, photoacoustic imaging (PAI), which uses laser pulse induced ultrasound waves as the signal, has been studied to differentiate human skin layers and to help skin disease diagnosis. This perspective article gives a short review of OCTA and PAI in the field of photodermatology. After an introduction of the principles of OCTA and PAI, we describe the most updated results of skin disease imaging using these two optical imaging modalities. We also put an emphasis on dual modality imaging combining OCTA and photoacoustic tomography (PAT) for dermatological applications. In the end, the challenges and opportunities of these two imaging modalities in dermatology are discussed.
关键词： microvasculature,dermatology,Optical coherence tomography angiography,photoacoustic imaging,skin imaging
更新于2025-09-19 17:15:36
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On an inverse problem in photoacoustics
摘要： We consider the problem of reconstruction of the Cauchy data for the wave equation in ?3 and ?2 by the measurements of its solution on the boundary of the unit ball.
关键词： wave equation,Inverse problem,photoacoustic
更新于2025-09-19 17:15:36
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Azacalixphyrins as NIR photoacoustic contrast agents
摘要： Near-infrared (NIR) azacalixphyrins bearing aryl substituents strongly impacting the physico-chemical properties of the macrocycles were designed, enabling hyperchromic and bathochromic shifts of the absorption compared to their N-alkylated analogues. This engineering enhances the photoacoustic response under NIR excitation, making azacalixphyrins promising organic contrast agents that reach the 800–1000 nm range.
关键词： contrast agents,organic chromophores,photoacoustic imaging,NIR,azacalixphyrins
更新于2025-09-19 17:15:36
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Photoacoustic imaging of gold nanorods in the brain delivered via microbubble-assisted focused ultrasound: a tool for <i>in vivo</i> molecular neuroimaging
摘要： The protective barriers of the CNS present challenges during the treatment and monitoring of diseases. In particular, the blood brain barrier is a major hindrance to the delivery of imaging contrast agents and therapeutics to the brain. In this work, we use gas microbubble-assisted focused ultrasound to transiently open the blood brain barrier and locally deliver silica coated gold nanorods across the barrier. This particular nanoagent possesses a strong optical absorption which enables in vivo and ex vivo visualization of the delivered particles using ultrasound-guided photoacoustic imaging. The results of these studies demonstrate the potential of ultrasound-guided photoacoustics to image contrast agents delivered via microbubble-assisted focused ultrasound for longitudinal diagnostic imaging and for therapeutic monitoring of neurological diseases.
关键词： focused ultrasound,blood brain barrier opening,nanoparticles,ultrasound and photoacoustic imaging
更新于2025-09-19 17:15:36
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Laser-generated focused ultrasound transmitters with frequency-tuned outputs over sub-10-MHz range
摘要： Previous laser-generated focused ultrasound (LGFU) systems have been operated with >15 MHz frequency, allowing for high spatial precision (<100 lm). However, they have been limited only to proximal biomedical applications ex vivo with treatment depths smaller than 10 mm from the lens surface. Although the low-megahertz frequency operation has the advantage of a longer range of therapy, this requires a proper photoacoustic lens made of a nanocomposite coating over a spherically curved substrate whose transmission layer is physically designed for frequency-tuned outputs. This demands a fabrication method that can provide such a nanocomposite structure. We demonstrate photoacoustic lenses operated in an unexplored frequency range of 1–10 MHz, which can simultaneously produce high-amplitude pressure outputs suf?cient for pulsed acoustic cavitation. We physically design a spatially elongated photoacoustic output and then fabricate a transmitter by controlling the density of light-absorbing nanoscale elements in a solution form and by using a replica mold to shape the lens curvature. Our approach is validated by fabricating and characterizing planar transmitters and then applied to focal con?gurations. This offers various possibilities for LGFU-based treatments (e.g., pulsed cavitational therapy such as histotripsy) over the low-megahertz frequency range, which has not been realized by conventional LGFU systems.
关键词： laser-generated focused ultrasound,sub-10-MHz range,frequency-tuned outputs,photoacoustic lenses,acoustic cavitation
更新于2025-09-19 17:13:59
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Rod-based urchin-like hollow microspheres of Bi2S3: Facile synthesis, photo-controlled drug release for photoacoustic imaging and chemo-photothermal therapy of tumor ablation
摘要： Hollow nanostructures have been evoked considerable attention owing to their intriguing hollow interior for important and potential applications in drug delivery, lithium battery, catalysis and etc. Herein, Bi2S3 hollow microspheres with rod-based urchin-like nanostructures (denoted as U-BSHM) were synthesized through a facile and rapid ion exchanging method using a particular hard template. The growth mechanism of the U-BSHM has been investigated and illustrated by the morphological evolution of the different samples at early stages. The obtained U-BSHM exhibited strong and wide UV-vis-NIR absorption ability and outstanding photothermal conversion efficiency. Thus, the U-BSHM can be used as spatio-temporal precisely controlled carrier by loading the mixture of 1-tetradecanol (phase change material, PCM) with melting point around 38 oC and hydrophilic chemotherapeutic doxorubicin hydrochloride (denoted as DOX) into the hollow interior to form (PCM+DOX)@Bi2S3 nanocomposites (denoted as PD@BS) for photoacoustic (PA) imaging and chemo-photothermal therapy of the tumors. When exposed to 808 nm near infrared light (NIR) laser irradiation, this nanocomposites could elevate the temperature of the surroundings by absorption and conversion of the NIR photons into heat energy, which inducing the triggered release of DOX from the hollow interior once the temperature reach up to the melting point of PCM. The killing efficiency of the chemo-photothermal therapy was systematically validated both in vitro and in vivo. In the meanwhile, the implanted tumor was completely restrained through PA imaging and combined therapies. Therefore, this kind of urchin-like hollow nanostructures would be used as important candidates for the multimodal bioimaging and therapy of tumors.
关键词： chemo-photothermal therapy,sacrificed template method,photo-controlled drug release,photoacoustic imaging,Bi2S3
更新于2025-09-19 17:13:59
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A Sensitive Carbon Dioxide Sensor Based on Photoacoustic Spectroscopy with a Fixed Wavelength Quantum Cascade Laser
摘要： A photoacoustic spectroscopy (PAS) based carbon dioxide (CO2) sensor with a fixed wavelength quantum cascade laser (FW-QCL) was demonstrated. The emission wavelength of the FW-QCL at 4.42 μm in the mid-infrared spectral region matched a fundamental CO2 absorption line. Amplitude modulation of the laser intensity was used to match the resonant photoacoustic (PA) cell. The noise from the background was reduced with the correlation demodulation technique. The experimental results showed that the sensor had excellent signal stability and a concentration linear response. When the integration time was 1 s, a 1σ minimum detection limit (MDL) of 2.84 parts per million (ppm) for CO2 detection was achieved. The long-term stability of the sensor was evaluated by means of an Allan deviation analysis. With an integration time of ~100 s, the MDL was improved to 1 ppm. This sensor was also used to measure the CO2 concentration from some common emission sources, such as cigarette smoking, automobile exhaust, and the combustion of some carbon-containing materials, which confirmed the stability and robustness of the reported FW-QCL based CO2-PAS sensor system.
关键词： carbon dioxide detection,photoacoustic spectroscopy,quantum cascade laser
更新于2025-09-19 17:13:59
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An Economic Photoacoustic Imaging Platform using Automatic Laser Synchronization and Inverse Beamforming
摘要： We present a proof-of-concept of an automatic integration of photoacoustic (PA) imaging on clinical ultrasound (US) imaging platforms. Here we tackle two critical challenges: the laser synchronization and the inaccessibility to the beamformer core embedded in commercial US imaging platform. In particular, the line trigger frequency (LTF) estimation and the asynchronous synthetic aperture inverse beamforming (ASAIB) were developed and evaluated in both k-Wave simulation and phantom experiment. The proposed method is an economical solution to enable PA imaging on a greater number of US equipment to further thrive the PA imaging research community.
关键词： asynchronous,inverse beamforming,Photoacoustic imaging
更新于2025-09-19 17:13:59