• Advanced Photonics
  • Vol. 3, Issue 2, 026003 (2021)
Jiao Li1、†, Yixin Yao1、2、3, Liwen Jiang1、2、3, Shuai Li1, Zhihao Yi1、2、3, Xieyu Chen1、2、3, Zhen Tian1、2、3、*, and Weili Zhang4、*
Author Affiliations
  • 1Tianjin University, School of Precision Instruments and Optoelectronics Engineering, Tianjin, China
  • 2Tianjin University, Center for Terahertz Waves, Tianjin, China
  • 3Ministry of Education, Key Laboratory of Optoelectronics Information and Technology, Tianjin, China
  • 4Oklahoma State University, School of Electrical and Computer Engineering, Stillwater, Oklahoma, United States
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    Radiation at terahertz frequencies can be used to analyze the structural dynamics of water and biomolecules, but applying the technique to aqueous solutions and tissues remains challenging since terahertz radiation is strongly absorbed by water. While this absorption enables certain analyses, such as the structure of water and its interactions with biological solutes, it limits the thickness of samples that can be analyzed, and it drowns out weaker signals from biomolecules of interest. We present a method for analyzing water-rich samples via time-domain terahertz optoacoustics over a 104-fold thickness ranging from microns to centimeters. We demonstrate that adjusting the temperature to alter the terahertz optoacoustic (THz-OA) signal of water improves the sensitivity with which it can be analyzed and, conversely, can reduce or even “silence” its signal. Temperature-manipulated THz-OA signals of aqueous solutions allow detection of solutes such as ions with an order of magnitude greater sensitivity than terahertz time-domain spectroscopy, and potentially provide more characteristic parameters related to both terahertz absorption and ultrasonic propagation. Terahertz optoacoustics may be a powerful tool for spectroscopy and potential imaging of aqueous solutions and tissues to explore molecular interactions and biochemical processes.

    1 Introduction

    Terahertz radiation, with wavelengths between 0.03 and 0.3 mm, can provide unique insights into the composition, structure, and dynamics of inorganic and biological materials unavailable with radiation of other frequencies.15 It can detect numerous rotational and vibrational transitions in proteins, DNA, RNA, and sugars,610 as well as transitions in water that depend on hydrogen bonding, which means that it is sensitive to interactions of water with solutes such as ions.1118 The extremely low energy of terahertz radiation makes it safe for analysis of living samples. Because of these advantages, terahertz spectroscopy and imaging have developed into an effective technique for detecting proteins, DNA, RNA, sugars, and cells in vitro and in vivo,9,10,1923 for analyzing structures and dynamics of water and ion hydration,18,2426 for differentiating tumors from healthy cells based on water content,2731 and for evaluating tissues for the presence of viruses or other pathology.3234

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    Jiao Li, Yixin Yao, Liwen Jiang, Shuai Li, Zhihao Yi, Xieyu Chen, Zhen Tian, Weili Zhang. Time-domain terahertz optoacoustics: manipulable water sensing and dampening[J]. Advanced Photonics, 2021, 3(2): 026003
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    Category: Research Articles
    Received: Dec. 12, 2020
    Accepted: Mar. 1, 2021
    Published Online: Apr. 6, 2021
    The Author Email: Tian Zhen (tianzhen@tju.edu.cn), Zhang Weili (weili.zhang@okstate.edu)