Terahertz time-domain attenuated total reflection spectroscopy integrated with a microfluidic chip

Ying Fu; Tunan Chen; Ligang Chen; Yuansen Guo; Zhongbo Yang; Ning Mu; Hua Feng; Mingkun Zhang; Huabin Wang

doi:10.3389/fbioe.2023.1143443

Terahertz time-domain attenuated total reflection spectroscopy integrated with a microfluidic chip

Front Bioeng Biotechnol. 2023 Mar 13:11:1143443. doi: 10.3389/fbioe.2023.1143443. eCollection 2023.

Authors

Ying Fu^{1

2}, Tunan Chen³, Ligang Chen^{1

2}, Yuansen Guo^{1

2}, Zhongbo Yang^{1

2}, Ning Mu³, Hua Feng³, Mingkun Zhang^{1

2}, Huabin Wang^{1

2}

Affiliations

¹ Center of Super-Resolution Optics & Chongqing Engineering Research Center of High-Resolution and Three-Dimensional Dynamic Imaging Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, China.
² Chongqing School, University of Chinese Academy of Sciences, Chongqing, China.
³ Department of Neurosurgery and Key Laboratory of Neurotrauma, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China.

Abstract

The integration of a microfluidic chip into terahertz time-domain attenuated total reflection (THz TD-ATR) spectroscopy is highly demanded for the accurate measurement of aqueous samples. Hitherto, however little work has been reported on this regard. Here, we demonstrate a strategy of fabricating a polydimethylsiloxane microfluidic chip (M-chip) suitable for the measurement of aqueous samples, and investigate the effects of its configuration, particularly the cavity depth of the M-chip on THz spectra. By measuring pure water, we find that the Fresnel formulae of two-interface model should be applied to analyze the THz spectral data when the depth is smaller than 210 μm, but the Fresnel formula of one-interface model can be applied when the depth is no less than 210 μm. We further validate this by measuring physiological solution and protein solution. This work can help promote the application of THz TD-ATR spectroscopy in the study of aqueous biological samples.

Keywords: attenuated total reflection; evanescent field; lactate dehydrogenase; microfluidic chip; terahertz.

Grants and funding

This work is supported by the National Natural Science Foundation of China (62175238), the National Key Research and Development Program of China (2021YFA1301503), the University of Chinese Academy of Sciences Supported Program for Tackling Key Problems in Science and Technology (E029610601), Natural Science Foundation of Chongqing (cstc2019jcyj-msxmX0051), and Youth Innovation Promotion Association CAS (2022390).