Zhang Bo, Jiang Jiachen, Zhang Xian, Jia Yunjiang, Zhu Xiaosong, Shi Yiwei
School of Information Science and Technology, Fudan University, Shanghai 200438, China.
Zhongshan - Fudan Joint Innovation Center, Zhongshan 528400, Guangdong Province, China.
Anal Chem. 2023 Aug 29;95(34):12811-12818. doi: 10.1021/acs.analchem.3c01784. Epub 2023 Aug 15.
A low-frequency flexible resonant photoacoustic (PA) gas sensor using an O-shaped multipass cell is demonstrated. The PA sensor employed a flexible gradually tapered leaky hollow core fiber (LHCF). The LHCF was bent to be an end-to-end structure to make full use of the incident light. Additionally, the two ends of the LHCF were put inside a single buffer chamber, yielding an equivalent H-type acoustic resonator. The geometric size was reduced thanks to the bending structure. The geometric length of the LHCF was 500 mm. A micro-electro-mechanical-systems electrical microphone was installed at the center of the resonant tube to detect the PA signal. The proposed PA gas sensor exhibited a first-order longitudinal resonance frequency of 408 Hz. Trace acetylene (CH) was used as the target gas. The minimum detectable limit was calculated to be 25.8 parts-per-billion (ppb) with an average time of 400 s, which was 1.93 times higher than that of a single-pass PA gas sensor. The normalized noise-equivalent absorption coefficient and the PA cell constant were calculated to be 9.6 × 10 W·cm·Hz and 8295 Pa/W·cm, respectively. The PA gas sensor owns a low resonance frequency and can be used for detection of most of the polar gaseous molecules, especially suitable for gas molecules with a long V-T relation time, such as carbon monoxide and carbon dioxide.
展示了一种使用O形多程池的低频柔性共振光声（PA）气体传感器。该PA传感器采用了柔性渐变锥形泄漏空心光纤（LHCF）。将LHCF弯曲成端对端结构以充分利用入射光。此外，将LHCF的两端置于单个缓冲室内，形成等效的H型声谐振器。由于弯曲结构，几何尺寸减小。LHCF的几何长度为500毫米。在谐振管中心安装了一个微机电系统电传声器来检测PA信号。所提出的PA气体传感器表现出408赫兹的一阶纵向共振频率。痕量乙炔（CH）用作目标气体。计算得出的最低可检测限为25.8十亿分之一（ppb），平均时间为400秒，这比单通道PA气体传感器的最低可检测限高1.93倍。归一化噪声等效吸收系数和PA池常数分别计算为9.6×10 W·cm·Hz和8295 Pa/W·cm。该PA气体传感器具有低共振频率，可用于检测大多数极性气态分子，特别适用于具有长V-T关系时间的气体分子，如一氧化碳和二氧化碳。
