Department of Physics, Incheon National University, Incheon 22012, Korea.
Division of Science Education, Kangwon National University, Chuncheon 24341, Korea.
Sensors (Basel). 2021 May 2;21(9):3161. doi: 10.3390/s21093161.
We report on a prototypical study of the detection of microplastic embedded in table salts by using terahertz time-domain spectroscopy. In the experiment, high-density polyethylene (HDPE) of sizes from 150 to 400 μm are used as a representative microplastic and mixed with table salts. Analyzing terahertz transmittance with an effective medium model, we extract various optical properties such as refractive index, absorption coefficient, and real/imaginary parts of the dielectric constant of the mixture. Consequently, the optical properties exhibit volume-ratio-dependence in 0.1-0.5 THz regimes. Especially, the refractive index and the real part of the dielectric constant possess monotonic frequency dependence, meaning that the quantities can be relevant indicators for the detection of the microplastic in terms of practical applications. Our work proves that terahertz time-domain spectroscopy can pave a way to recognize microplastic mixed with salts and be expanded for detecting various micro-sized particles.
我们报告了一项使用太赫兹时域光谱检测嵌入食盐中的微塑料的原型研究。在实验中，使用尺寸为 150 至 400 μm 的高密度聚乙烯（HDPE）作为代表性的微塑料，并将其与食盐混合。通过有效介质模型分析太赫兹透过率，我们提取了混合物的折射率、吸收系数以及介电常数的实部和虚部等各种光学性质。结果表明，在 0.1-0.5 THz 范围内，光学性质表现出与体积比相关的依赖性。特别是折射率和介电常数的实部具有单调的频率依赖性，这意味着这些量可以作为实际应用中检测微塑料的相关指标。我们的工作证明，太赫兹时域光谱可以为识别与盐混合的微塑料铺平道路，并可扩展用于检测各种微尺寸颗粒。
