The temperature disturbances greatly influence the performances of microfluidic chips during the working process. It is therefore important to evaluate the thermo-optic properties of microfluidic materials. Here, we measure the thermo-optic property by employing a fiber optic surface plasmon resonance (SPR) sensor combined with a thermocouple. This setup can be applied for embedding in microfluidic materials or directly detecting fluidic samples. Three fiber optic SPR sensors were fabricated with a $400~\mu m$ -bare-core, $600~\mu m$ -bare-core and mismatched-core structures. The thermo-optic responses of the three sensors were compared to determine the optimum sensor structure. The thermo-optic property of polydimethylsiloxane was then investigated over the full temperature detection range of 25–200 °C. The thermo-optic coefficient of polydimethylsiloxane was determine to be $- 4.19\times 10^{-4}$ RIU/°C, which agrees well with previous reports. The thermo-optic properties of ethanol and brine were also evaluated to confirm the universality of the proposed measurement method. To our knowledge, this is the first reported detection of thermo-optic properties using a fiber optic SPR sensor.

中文翻译：

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使用基于表面等离子体共振的光纤进行热光特性测量

温度扰动极大地影响微流控芯片在工作过程中的性能。因此，重要的是评估微流体材料的热光特性。在这里，我们通过采用光纤表面等离子体共振 (SPR) 传感器与热电偶相结合来测量热光特性。此设置可用于嵌入微流体材料或直接检测流体样品。三个光纤 SPR 传感器是用一个 $400~\mu m$ - 裸核， $600~\mu m$ -裸核和不匹配的核心结构。比较三个传感器的热光响应以确定最佳传感器结构。然后在 25–200 °C 的全温度检测范围内研究了聚二甲基硅氧烷的热光特性。聚二甲基硅氧烷的热光系数确定为 $- 4.19\times 10^{-4}$ RIU/°C，与之前的报告一致。还评估了乙醇和盐水的热光特性，以确认所提出的测量方法的普遍性。据我们所知，这是首次使用光纤 SPR 传感器检测热光特性。