Browsing by Author "Lin, Jun"

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    Ppbv-Level Ethane Detection Using Quartz-Enhanced Photoacoustic Spectroscopy with a Continuous-Wave, Room Temperature Interband Cascade Laser
    (MDPI, 2018) Li, Chunguang; Dong, Lei; Zheng, Chuantao; Lin, Jun; Wang, Yiding; Tittel, Frank K.
    A ppbv-level quartz-enhanced photoacoustic spectroscopy (QEPAS)-based ethane (C2H6) sensor was demonstrated by using a 3.3 μm continuous-wave (CW), distributed feedback (DFB) interband cascade laser (ICL). The ICL was employed for targeting a strong C2H6 absorption line located at 2996.88 cm−1 in its fundamental absorption band. Wavelength modulation spectroscopy (WMS) combined with the second harmonic (2f) detection technique was utilized to increase the signal-to-noise ratio (SNR) and simplify data acquisition and processing. Gas pressure and laser frequency modulation depth were optimized to be 100 Torr and 0.106 cm−1, respectively, for maximizing the 2f signal amplitude. Performance of the QEPAS sensor was evaluated using specially prepared C2H6 samples. A detection limit of 11 parts per billion in volume (ppbv) was obtained with a 1-s integration time based on an Allan-Werle variance analysis, and the detection precision can be further improved to ~1.5 ppbv by increasing the integration time up to 230 s.
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    Sharp-peaked lanthanide nanocrystals for near-infrared photoacoustic multiplexed differential imaging
    (Springer Nature, 2024) Loh, Kang Yong; Li, Lei S.; Fan, Jingyue; Goh, Yi Yiing; Liew, Weng Heng; Davis, Samuel; Zhang, Yide; Li, Kai; Liu, Jie; Liang, Liangliang; Feng, Minjun; Yang, Ming; Zhang, Hang; Ma, Ping’an; Feng, Guangxue; Mu, Zhao; Gao, Weibo; Sum, Tze Chien; Liu, Bin; Lin, Jun; Yao, Kui; Wang, Lihong V.; Liu, Xiaogang
    Photoacoustic tomography offers a powerful tool to visualize biologically relevant molecules and understand processes within living systems at high resolution in deep tissue, facilitated by the conversion of incident photons into low-scattering acoustic waves through non-radiative relaxation. Although current endogenous and exogenous photoacoustic contrast agents effectively enable molecular imaging within deep tissues, their broad absorption spectra in the visible to near-infrared (NIR) range limit photoacoustic multiplexed imaging. Here, we exploit the distinct ultrasharp NIR absorption peaks of lanthanides to engineer a series of NIR photoacoustic nanocrystals. This engineering involves precise host and dopant material composition, yielding nanocrystals with sharply peaked photoacoustic absorption spectra (~3.2 nm width) and a ~10-fold enhancement in NIR optical absorption for efficient deep tissue imaging. By combining photoacoustic tomography with these engineered nanocrystals, we demonstrate photoacoustic multiplexed differential imaging with substantially decreased background signals and enhanced precision and contrast.