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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
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Application of Quartz Tuning Fork in Photodetector Based on Photothermal Effect
摘要： A photodetector with a commercial quartz tuning fork (QTF) based on photothermal effect was demonstrated. Unlike the commonly used thermosensitive elements, a QTF with the mechanical resonance ability and the piezoelectric effect was used to amplify the photothermal signal. Operating at the optimal operating distance and modulation signal duty ratio selected for the photodetector, the photodetector achieved a good linear response at the wavelength of 1550 nm and 980 nm. And the photoresponsivity of the photodetector reach up to 515 mV/mW at the wavelength of 1550 nm. More important, the detection sensitivity of 0.75 pW at 203 s integration time has been achieved by using the Allan deviation analysis.
关键词： photothermal effect,Photodetector,quartz tuning fork
更新于2025-09-12 10:27:22
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Quartz-enhanced conductance spectroscopy for nanomechanical analysis of polymer wire
摘要： Quartz-enhanced conductance spectroscopy is developed as an analytical tool to investigate dynamic nanomechanical behaviors of polymer wires, in order to determine the glass transition temperature (Tg). A polymethyl methacrylate (PMMA) microwire with a diameter of 10 lm was bridged across the prongs of a quartz tuning fork (QTF). With the advantage of QTF self-sensing as compared with micro-cantilevers or other resonators, the resonance frequency and Q factor can be directly determined by means of its electrical conductance spectra with respect to the frequency of the external excitation source (dI/dV vs f), and therefore, no optical beam is required. The Tg of the PMMA microwire was determined by the maximum loss modulus of the QTF, calculated from the resonance frequency and the Q factor as a function of temperature. The measured Tg of the PMMA is 103 (cid:2)C with an error of 62 (cid:2)C. Both heating/cooling and physical aging experiments were carried out, demonstrating that the technique is both reversible and reproducible.
关键词： PMMA,polymer wire,quartz tuning fork,nanomechanical analysis,glass transition temperature,Quartz-enhanced conductance spectroscopy
更新于2025-09-04 15:30:14
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Electrochemical etching of lightweight nanotips for high quality-factor quartz tuning fork force sensor: atomic force microscopy applications
摘要： Commercially available quartz tuning forks (QTFs) can be transformed into self-sensing and actuating force sensors by micro-assembling a sharp tip on the apex of a tine. Mass of the tip is critical in determining the quality (Q)-factor of the sensor, therefore, fabrication of the lightweight nanotips is a precondition for high Q-factor QTF sensors. The work reports fabrication of very lightweight tungsten nanotips with a two-step electrochemical etching technique which can be used to develop high Q-factor QTF force sensor. First, a tungsten wire with protective coating at one end (1–2 mm) is etched with a trapezoidal waveform to form a lengthy (～2–5 mm) and slender (diameter ～10–40 μm) micro-needle. In the second step, sharp tip apex is fabricated with a direct current etching. High Q-factor (6600–8000) QTF force sensors have been developed with the fabricated nanotips. Atomic force microscope scanning of nano-grating and a triblock copolymer surface validates the scanning performance of the developed sensors.
关键词： quartz tuning fork,nanotips,atomic force microscopy,force sensor,electrochemical etching
更新于2025-09-04 15:30:14