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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Multi-points ultrasound detection with multiple FBGs and a pseudo-synchronous method
摘要： A novel pseudo-synchronous method(PSM)is proposed to realize the multi-points detection of ultrasound with fiber Bragg sensors (FBGs) connected in serials, to overcome the problems encountered by employing conventional wavelength demodulator for FBGs at relatively low repeat frequency(~1kHz), comparing with the much higher frequency up to several tens of kHz of the ultrasound to be detected. The novel detection scheme has been demonstrated effectively when the ultrasound was excited and propagating on the surfaces of an aluminium plate and a section of stainless steel tube, respectively. The experimental measurement shows the in practical detection method has good prospect application such as the non-destructive test (NDT), etc.
关键词： pseudo-synchronous method,ultrasound detection,fiber Bragg gratings
更新于2025-09-16 10:30:52
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Fiber-optic ultrasound transmitter based on multi-mode interference in curved adhesive waveguide
摘要： Fiber-optic ultrasound transmitters can be used in structural health monitoring, material characterization, and biomedical imaging. However, the bandwidth of current fiber-optic ultrasound transmitters is tens of MHz which prevents the ultrasound image on cells with resolution of μm level. Here, ultra-compact in-fiber ultrasound transmitter is proposed by using the multi-mode interference in the curved UV-cured adhesive waveguide, which is fabricated between two fiber endfaces over a sandwiched core-offset spliced fiber segment. The curved adhesive waveguide can improve the contrast of device reflection spectrum from 2.7 dB to 21.7 dB. The ultrasound is generated by optical pulse excitation via photoabsorption and thermal expansion of UV-cured adhesive, and then detected via the multi-mode interference of the same waveguide with hundreds of Hz to 306 MHz broad transverse acoustic waves. This ultra-compact and cost-effective device offers new opportunities to the advanced biomedical and ultrasound-based applications.
关键词： Fiber-optic,Ultrasound transmitter,Multi-mode interference
更新于2025-09-16 10:30:52
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Fabrication of Silicon Microfluidic Chips for Acoustic Particle Focusing Using Direct Laser Writing
摘要： We have developed a fast and simple method for fabricating microfluidic channels in silicon using direct laser writing. The laser microfabrication process was optimised to generate microfluidic channels with vertical walls suitable for acoustic particle focusing by bulk acoustic waves. The width of the acoustic resonance channel was designed to be 380 μm, branching into a trifurcation with 127 μm wide side outlet channels. The optimised settings used to make the microfluidic channels were 50% laser radiation power, 10 kHz pulse frequency and 35 passes. With these settings, six chips could be ablated in 5 h. The microfluidic channels were sealed with a glass wafer using adhesive bonding, diced into individual chips, and a piezoelectric transducer was glued to each chip. With acoustic actuation at 2.03 MHz a half wavelength resonance mode was generated in the microfluidic channel, and polystyrene microparticles (10 μm diameter) were focused along the centre‐line of the channel. The presented fabrication process is especially interesting for research purposes as it opens up for rapid prototyping of silicon‐glass microfluidic chips for acoustofluidic applications.
关键词： acoustophoresis,acoustofluidics,ultrasound,laser micromachining,particle manipulation,microfabrication
更新于2025-09-16 10:30:52
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[IEEE 2019 Far East NDT New Technology & Application Forum (FENDT) - Qingdao, Shandong province, China (2019.6.24-2019.6.27)] 2019 Far East NDT New Technology & Application Forum (FENDT) - Visual Detection of AM Surface Defects Based on Laser Ultrasound Technology
摘要： Selective Laser Melting (SLM) process is a kind of Additive Manufacturing (AM) method, which can process parts with arbitrary complex geometry. However, macro-defects will destroy the mechanical properties of metal materials manufactured by SLM. Laser ultrasound can excite broadband surface waves and realize non-contact nondestructive testing of surface defects. In this paper, 316L stainless steel samples are prepared by SLM process are used for laser ultrasonic detection. According to the diffraction phenomenon of surface wave at the defect, a laser ultrasonic B-scan detection platform is built. The B-scan images of different length defects on the sample surface are obtained, and the quantitative detection of surface defects is realized quickly. In order to further improve the signal-to-noise ratio and the accuracy of imaging detection, EEMD (Ensemble Empirical Mode Decomposition) denoising is applied to the collected ultrasonic signal, which improves the accuracy of imaging, makes the signal more stable and realizes the visual detection of surface length defects clearly and intuitively.
关键词： b-scan,additive manufacturing,laser ultrasound technology,EEMD
更新于2025-09-16 10:30:52
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Efficacy and safety of radiofrequency, microwave and laser ablation for treating papillary thyroid microcarcinoma: a systematic review and meta-analysis
摘要： Background: To evaluate the efficacy and safety of radiofrequency ablation (RFA), microwave ablation (MWA) and laser ablation (LA) for treating papillary thyroid microcarcinoma (PTMC). Materials and methods: PUBMED and EMBASE were searched for studies on the efficacy and safety of RFA, MWA and LA for treating PTMC. The standard mean difference of the tumor volume before and after therapy and the proportion of complete disappearance, local recurrence, distant metastasis and complications were assessed using both fixed or random-effects modeling. Heterogeneity among studies was determined using the Q statistic for the pooled estimates and the inconsistency index I2. Results: A total of 12 eligible studies, including a sample size of 1187 patients and 1284 PTMCs, were used. RFA, MWA and LA all showed a significant reduction in tumor volume of PTMCs (p < 0.05). Though MWA demonstrated superior efficacy over the other two therapies for volume reduction, the differences were not statistically significant. Additionally, the pooled proportion of complete disappearance after RFA was the highest (76.2%), and the pooled proportion of recurrence for RFA was the lowest (0.01%) among the three therapeutic methods, but no significant difference was detected. There was no event of distant metastasis during the follow-up in all of these studies. Few major complications were encountered; the pooled proportion of complications for RFA (1.73%), MWA (6.0%) and LA (0.92%) was low, revealing no significant differences (p > 0.05). Conclusion: RFA, MWA and LA are acceptable treatments to manage PTMCs in terms of efficacy and safety for non-surgical candidates.
关键词： radiofrequency ablation,Papillary thyroid microcarcinoma,laser ablation,ultrasound,microwave ablation
更新于2025-09-12 10:27:22
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Direct and Indirect Flap Measurements in Femtosecond Laser–Assisted In Situ Keratomileusis
摘要： To compare direct and indirect LASIK flap thickness measurements using ultrasound and Scheimpflug technology. Eighty-two eyes treated with laser-assisted in situ keratomileusis refractive surgery using a femtosecond laser (IntraLase FS150) were prospectively included in the study. Flap thickness was set to 115 mm. Corneal flap thickness was measured using the direct method—ie, ultrasound pachymetry immediately after flap construction in the presence of cavitation bubbles—and indirect methods, with subtraction of intraoperative post-lift corneal thickness measured using ultrasound pachymetry (intrastroma) from preoperative central corneal thickness using ultrasound (Indirect-US) or Scheimpflug thinnest pachymetry (Indirect-Scheimpflug). Mean flap thickness was overestimated using the indirect methods, Indirect-US and Indirect-Scheimpflug (122.6 6 24.5 mm and 128.1 6 26.1 mm, respectively; P , 0.0060 and P , 0.0001, respectively). There were no significant correlations between the direct and indirect methods. Indirect-Scheimpflug was significantly higher (P = 0.0122) than Indirect-US. The closest average flap thickness compared with the set parameter of 115 mm was that of the direct method (115.6 6 8.6 mm; 95% confidence interval: 21.3 to 2.5; P = 0.5163). The direct method provided the lowest SD of all groups (SD: 8.64). The direct method of flap thickness measurement was the most comparable to the set parameter compared with the indirect subtraction methods. Additional studies are needed to determine which method allows for the most accurate measurement of flap thickness.
关键词： flap thickness,femtosecond laser,laser in situ keratomileusis,Scheimpflug,ultrasound
更新于2025-09-12 10:27:22
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Early tongue carcinomas (clinical stage I and II): echo-guided three-dimensional diode laser mini-invasive surgery with evaluation of histological prognostic parameters. A study of 85 cases with prolonged follow-up
摘要： The management of patients with early stage (cT1–T2) tongue squamous cell carcinoma without clinicoradiologic evidence of neck node metastasis (cN0) has been widely debated over the last 3 decades and still remains controversial. Nevertheless, the identification of patients with low-stage tumours at high-risk for occult cervical metastases is imperative before planning treatments of primary tumours, as well as that of prognostic markers which may possibly select those patients who may benefit of additional workup after surgery in view of the high metastatic potential of the primary tumour. The pre-surgical evaluation of tongue malignant primary tumour (for assessing lateral and deep margins) along with diode laser surgery (with accurate incision, bleeding-free and with reduced/absent post-surgical complications) may lead to a more conservative but equally decisive surgical treatment, also with a greater patient compliance. We studied 85 consecutive cases of cT1–T2 N0 tongue squamous cell carcinoma who had been managed by the following diagnostic/therapeutic protocol: pre-operative high definition ultrasound examination for the evaluation of size and depth, followed by three-dimensional surgical excision by diode laser (wavelength of 800 ± 10 nm, output power of 8 W in continuous wave, flexible optic fibre of 320 μm in contact mode) and detailed histological analyses of well-established prognostic parameters (tumour grade, thickness, depth, front of infiltration and surgical margins) with statistical analysis. No post-surgical photobiomodulation was performed. Overall, 58.82% of patients were stage I, 18% stage II, and the most frequent histotype was squamous cell carcinoma (97.64%). Large nests invasion pattern was observed in 64 cases, expansive pattern in 9, invasion in single cells in 12; front of invasion involved the muscle in 62 cases, vessels in 6, nerves in 15; peritumoural vascular invasion was assessed in 6 patients and perineural invasion in 15. Selective neck lymphadenectomy was performed in 9 cases, and clinically occult node metastases were detected in two cases. At follow-up, 78 patients (98.73%) were alive and free of disease, one patient experienced tumour-related death, while the remaining 6 died for non-disease-related causes. All the histological prognostic parameters were statistically significant (χ2 test; p = 0.05), thus leading to a prognostic weight classification with a three-tiered stratification. On the bases of these results, the authors maintain that the reported diagnostic/therapeutic protocol, including the pre-operative echo-guided three-dimensional evaluation, the following diode laser mini-invasive surgery for tumour excision and the histological examination along with the proposed three-tiered stratification of histological prognostic parameters may allow proper management of clinical stage I and II early tongue carcinomas.
关键词： Ultrasound,Nodal metastasis,Tongue cancer,Diode laser surgery,Neck dissection,Histological prognostic parameters
更新于2025-09-12 10:27:22
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Design of a remote and integrated Sagnac interferometer that can generate narrowband guided wave through the use of laser and effective optics to detect defects occurred in plates
摘要： To inspect the integrity of specimens that are moving or no space available to mount sensors on their surfaces, laser generated guided wave (GW) becomes the only feasible option. However, conventional GW generated by laser-based emission is in broadband frequency range. Hence, unwanted GW modes, along with the emitted desired GW mode, also get produced simultaneously to the inspected specimen. The results generated from reflected GW become chaotic, making the identification of GW signals truly reflected by defects very difficult. Hence, substantial research efforts have been spent on reducing unwanted GW modes by spatially modulating the laser pattern to emit narrowband GW. Previous methods to generate narrowband GW include the use of slit mask, diffractive grating, lenticular array, and interference of laser beam. Among these techniques, each has certain shortcomings. A recent research achievement is the design of the integrated optical Mach-Zehnder system (IOMZ) (J. Chen et al, Opt. Lett., 42, 4255, 2017). It can emit desired narrowband Lamb wave into the aluminum plate by using pulsed laser and the designed optical system. Although the results showed IOMZ’s ability in emitting narrowband GW mode, significant unwanted noise was also generated, making the signal-to-noise ratio (SNR) of the received GW signals rather low. In this study a new optical system to overcome the shortcoming of the above reported devices is proposed. It is called integrated Sagnac interferometer-based optical system (SIOS) which can minimize generation of unwanted noise and substantially improve the SNR of reflected GW signals. A comparison study is also presented to illustrate the effectiveness of SIOS is superior to that of the IOMZ. Experimental results reveal that the proposed SIOS is promising for remote nondestructive testing and evaluation.
关键词： Non-destructive testing,Laser,Optical systems,Narrowband laser generated ultrasound,Guided wave,Optical Sagnac interferometer
更新于2025-09-12 10:27:22
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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Ultrasonically Steerable Graded-Index Optical Waveguides for Deep Tissue Light Delivery: Theory and Applications
摘要： Graded-index (GRIN) fibers have been used as implantable optical waveguides to guide light and relay images through the depth of the tissue. We have recently shown that non-invasive ultrasound can generate refractive index gradients within the tissue that form virtual GRIN lenses for imaging and photostimulation deep into the tissue. Here we present the theory behind this idea by analyzing the coupled acoustic-photonic system that models the interaction of light with the ultrasonically modulated medium. We will discuss how changing the parameters of ultrasound will change the confinement and guiding of light within the modulated medium. We will also demonstrate that using a custom-designed cylindrical ultrasonic array, the pressure interference can be controlled to sculpt complex patterns of light in the medium, such as dipole and quadrupole shapes, suitable for multisite imaging. Finally, we will discuss experimental results corroborating the theoretical predictions to generate single and multisite in situ virtual lenses that can be used for fluorescent imaging of mouse brain tissue that expresses green fluorescent protein (GFP).
关键词： refractive index gradients,fluorescent imaging,Graded-index fibers,acousto-optic system,ultrasound,virtual GRIN lenses,photostimulation
更新于2025-09-12 10:27:22
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Comparison of the effects of low-level laser and pulsed and continuous ultrasound on pain and physical disability in chronic non-specific low back pain: a randomized controlled clinical trial
摘要： Objective: To compare the short-term effects of pulsed laser and pulsed and continuous ultrasound on pain and functional disability in women with chronic non-specific low back pain. Methods: The sample was composed of 100 volunteers randomly allocated into four groups: The Pulsed Laser Group (n = 26) was treated with 3 J/cm2; the Pulsed Ultrasound Group (n = 24; 3 MHz) was treated with 1 W/cm2; the Continuous Ultrasound Group (n = 26; 1 MHz) was treated with 1 W/cm2; and a Control Group (n = 24), where the patients were still waiting for treatment. Before and after 10 sessions of treatment, the intensity of pain was assessed using the visual analogue scale (VAS), the quality of pain was evaluated using the McGill pain questionnaire and functional disability was investigated using the Roland–Morris questionnaire. Results: The three treated groups exhibited a decrease in pain (p < 0.001); the Pulsed Laser Group showed the greater relative gain (91.2%), Meanwhile, the Control Group exhibited a worsening of ? 5.8%. The three treated groups demonstrated improvement in the quality of pain (McGill) in the total, sensory and affective dimensions (p < 0.005; p < 0.002; p < 0.013, respectively). All treated groups showed a decrease in functional disability (p < 0.001), but the Pulsed Ultrasound Group showed the highest relative gain (83.3%). Conclusions: The three modalities have significant effects to decreasing low back pain and improving functional disability in women with non-specific chronic low back pain, but the pulsed low-level laser had the best results on pain while the pulsed ultrasound had the best results on improve the functional disability.
关键词： Laser therapy and ultrasound therapy,Low back pain
更新于2025-09-12 10:27:22