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Fish oil preparation inhibits leukocyte recruitment and bands that characterize inflamed tissue in a model of phenol-induced skin inflammation: percutaneous penetration of a topically applied preparation demonstrated by photoacoustic spectroscopy
摘要： Fish oil (FO) is a natural source of omega-3 fatty acids, with well-established beneficial effects in inflammatory diseases when FO is orally administered. This study investigated the effects of a topically applied FO preparation (FOP) on phenol-induced ear edema and evaluated the percutaneous penetration of FOP in ear tissue. After applying phenol, groups of mice received FOP on the ear. After 1 h, ear tissue was collected to determine the percent inhibition of edema, myeloperoxidase activity, and to perform photoacoustic spectroscopy (PAS). Treatment with FOP did not reduce edema, but reduced myeloperoxidase activity. The FOP decreased the area of bands that characterize inflamed tissue and penetrated into the tissue. These results indicated an inhibitory effect of FOP on leukocyte recruitment in phenol-induced ear edema. These data support the applicability of PAS as a non-destructive method for evaluating the inflammatory response, percutaneous penetration and antiinflammatory activity of compounds.
关键词： ear edema,Fish oil,inflammation,phenol,skin,photoacoustic spectroscopy
更新于2025-09-23 15:22:29
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Advances in Mid-Infrared Spectroscopy-Based Sensing Techniques for Exhaled Breath Diagnostics
摘要： Human exhaled breath consists of more than 3000 volatile organic compounds, many of which are relevant biomarkers for various diseases. Although gas chromatography has been the gold standard for volatile organic compound (VOC) detection in exhaled breath, recent developments in mid-infrared (MIR) laser spectroscopy have led to the promise of compact point-of-care (POC) optical instruments enabling even single breath diagnostics. In this review, we discuss the evolution of MIR sensing technologies with a special focus on photoacoustic spectroscopy, and its application in exhaled breath biomarker detection. While mid-infrared point-of-care instrumentation promises high sensitivity and inherent molecular selectivity, the lack of standardization of the various techniques has to be overcome for translating these techniques into more widespread real-time clinical use.
关键词： point-of-care (POC),infrared lasers,MIR,photoacoustic spectroscopy,biomarkers,exhaled breath analysis,non-invasive diagnostics,QCL,quantum cascade lasers,mid-infrared
更新于2025-09-23 15:21:01
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Operando Analysis of Electron Accumulation in Titanium(IV) Oxide Particles in an Aqueous Suspension Using a Photoacoustic Spectroscopic Method
摘要： The time course of photoabsorption of an aqueous suspension of titanium(IV) oxide (TiO2) particles was studied using photoacoustic (PA) spectroscopy. In the absence of an electron acceptor and the presence of an electron donor, ultraviolet (UV) irradiation increased PA intensity because photoabsorption of the suspension increased due to trivalent titanium (Ti3+) species generated by electron accumulation in TiO2 particles. In contrast, the addition of methylene blue (MB) as an acceptor caused a decrease in PA intensity, indicating that accumulated electrons were consumed by reduction of MB to colorless leuco-MB. The results for various TiO2 particles indicated that Ti3+ density is determined by this method. Moreover, the measurement can be applicable to quantitative operando analysis for accumulated electrons in a photocatalytic reaction.
关键词： photoacoustic spectroscopy,photocatalytic reaction,Ti3+ density,electron accumulation,titanium(IV) oxide
更新于2025-09-23 15:19:57
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Photoacoustic spectroscopy telemetry of airport dangerous goods
摘要： A novel photoacoustic spectroscopy telemetry method of detecting trace acetylene gas using a quartz tuning fork is reported. A 1532-nm CW-DFB, fiber-coupled diode laser with power of 12 mW was used as the excitation source while an astronomical telescope was used to collect laser light scattered on the surface of the detected object at a distance of 6 m and the photoacoustic spectroscopy of acetylene was performed. The detection results are consistent with the standard near-infrared absorption coefficient of acetylene. This study provides a new direction for research in photoacoustic spectroscopy telemetry. Future work will quantitatively analyze acetylene gas.
关键词： Photoacoustic spectroscopy,telemetry,acetylene,dangerous goods.
更新于2025-09-19 17:15:36
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Noninvasive blood glucose detection by Quantum Cascade Laser
摘要： Quantum Cascade Laser (QCL) was invented in late 90s as a promising mid-infrared light source and contributed to the field of industry, military, medicine, and biology. The room temperature operation, watt-level output power, compact size, and wide tuning capability of this laser advanced the field of noninvasive blood glucose detection by exploring transmission, absorption, and photoacoustic spectroscopy. This review provides a complete overview of the recent progress and technical details of these spectroscopy techniques, using QCL as an infrared light source for detecting blood glucose concentration for diabetic patients.
关键词： transmission spectroscopy,Quantum Cascade Laser,mid-infrared,noninvasive blood glucose detection,photoacoustic spectroscopy,absorption spectroscopy
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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Intra-cavity multi-point sensor for C2H2 detection in photoacoustic spectroscopy based on acousto-optic Q-switched fiber laser
摘要： In this paper, we reported a new multi-point sensor for C2H2 detection based on photoacoustic spectroscopy and acousto-optic Q-switched fiber laser. Three transmission-type PAS cells were placed inside the fiber laser cavity and used for C2H2 detection simultaneously to demonstrate the potential of spatially resolved measurements. A maximum pulse peak power of ~544 mW was generated by the acousto-optic Q-switched fiber laser. The signal-to-noise ratios (SNR) calculated from the experimental results was 57.7 dB, 45.1 dB and 57.2 dB. This resulted in a minimum detection limit (MDL) for C2H2 of 1.73 ppmv, 7.82 ppmv and 1.93 ppmv for PAS cell 1, PAS cell 2 and PAS cell 3, respectively.
关键词： multi-point sensor,photoacoustic spectroscopy,fiber laser
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Optical Frequency Comb Photoacoustic Spectroscopy
摘要： Photoacoustic spectroscopy (PAS) based on continuous wave (cw) lasers provides high absorption sensitivity in small sample volume [1, 2] but it is usually restricted to single species detection because of the limited tunability of cw lasers. Broadband PAS has been demonstrated using cantilever-enhanced detectors in combination with incoherent [3] or supercontinuum [4] light sources modulated by conventional Fourier transform spectrometers (FTS), however, the spectral resolution was limited to a few cm-1. Here we report the first demonstration of optical frequency comb photoacoustic spectroscopy (OFC-PAS), which combines the wide spectral coverage and high resolution of frequency combs with the small sample volume of photoacoustic detection [5]. The OFC-PAS setup is based on a doubly-resonant optical parametric oscillator pumped by a femtosecond Tm:fiber laser with a repetition rate of 125 MHz. The intensity of the signal output centered at 3.3 μm is modulated at ~500 Hz using an FTS. One output of the FTS (4.8 mW of signal power) is directed to a 10-cm-long cantilever-enhanced photoacoustic cell with 8 mL volume (Gasera, PA201), while the other is measured with a photodetector and used for normalization of the PA spectrum. Figure 1(a) shows in red the room temperature OFC-PAS spectrum of the C-H stretch band of 100 ppm of CH4 in N2 at 1000 mbar and 1 GHz resolution (left axis) recorded in 200 s (no averaging). The blue curve shows the simulated absorption coefficient, (cid:68), based on the parameters from the HITRAN database (right axis). A zoom-in around the Q-branch region at 1000 mbar and 400 mbar is shown in Figs 1(b) and 1(c), demonstrating the high spectral resolution, no instrumental lineshape distortion, and good agreement with the simulation. The limit of detection (LOD), evaluated from the signal to noise ratio of the methane line at 3058 cm-1 at 1000 mbar, is 0.8 ppm in 200 s for power spectral density of 42 μW/cm-1. While this LOD is comparable to those obtained with other broadband PAS methods [3, 4], the resolution of OFC-PAS is more than two orders of magnitude better. The normalized noise equivalent absorption at 1000 mbar is 8 × 10-10 W cm-1 Hz -1/2, comparable to values reported with PAS based on cw lasers [2]. OFC-PAS thus extends the capability of optical sensors for high-resolution multicomponent trace gas analysis in small sample volumes.
关键词： high-resolution spectroscopy,optical frequency comb,trace gas analysis,Photoacoustic spectroscopy
更新于2025-09-12 10:27:22
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Fully Coupled Model for Frequency Response Simulation of Miniaturized Cantilever-Based Photoacoustic Gas Sensors
摘要： To support the development of miniaturized photoacoustic gas sensors, a fully coupled ?nite element model for a frequency response simulation of cantilever-based photoacoustic gas sensors is introduced in this paper. The model covers the whole photoacoustic process from radiation absorption to pressure transducer vibration, and considers viscous damping loss. After validation with experimental data, the model was further applied to evaluate the possibility of further optimization and miniaturization of a previously reported sensor design.
关键词： photoacoustic spectroscopy,sensor miniaturization,viscous damping,COMSOL
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Photoacoustic Spectroscopy Sensor with a Small-Gap Quartz Tuning Fork
摘要： Quartz tuning fork (QTF), a mature electric device which is widely used in electronic circuits for timing reference, has been investigated in photoacoustic spectroscopy in recent years. Due to the excellent immunity, high Q-factor, and compactness, utilizing a QTF for acoustic wave detection in photoacoustic spectroscopy, namely quartz-enhanced photoacoustic spectroscopy (QEPAS), is a significant innovative spectroscopy. In a QEPAS system, the QTF’s distance of the fork tines, the so-called gap, determines the space for acoustic wave generation. Traditional QTFs with a gap of 300 μm can satisfy the requirement when the excitation source which locates in the near-infrared spectrum range. While, some custom-made QTFs has been investigated to accommodate the mid-infrared laser with beam larger than ~400-500 μm [1,2]. Nevertheless, in the near-infrared range, the diameter of the laser beam is far smaller than that in the mid-infrared spectral range. When a QTF applied in the QEPAS system, the laser beam passes through the fork valley and excites the gas molecules. Notably, the acoustic wave generated by the reaction between the laser beam and the gas molecules can be viewed as spherical wave oscillation. The spherical wave propagation decreases with the cube of the distance, which suggests that the energy of the sound wave will diminish rapidly as the distance from the generation source point of the sound wave increases. So, employing a small-gap QTF can avoid energy losses and therefore improve the signal level of the QEPAS sensor. In this paper, a custom-made QTF with a small-gap of 200 μm used in the QEPAS sensor was demonstrated. A simulation of the optimal vertical position with respect to the QTF and the length of micro-resonator were developed by using the COMSOL Multiphysics. The experiment was also conducted and indicated that such a small-gap QTF has an improved performance in the QEPAS sensor system.
关键词： photoacoustic spectroscopy,acoustic wave detection,QEPAS,quartz tuning fork,small-gap
更新于2025-09-12 10:27:22