An in-fiber optofluidic Michelson interferometer fabricated by femtosecond laser micromachining technology was presented. The interferometer structure was prepared by a special optical fiber with two cores and a microchannel. One core was connected to the core of a single-mode fiber (SMF) and functioned as a sensing arm on the microchannel inner wall, the other core worked as a reference arm and was connected to the optical waveguide introduced by femtosecond laser processing. By combining with a ring cavity laser, the detection limit (DL) of the interferometer could be improved. The laser sensor presented a high linear response with a refractive index (RI) sensitivity of 1039.77 nm/RIU and the calculated DL could reach as low as 1.675 × 10⁻⁵ RIU. Then, the sensor measured different concentrations of vitamin C in tablets in the concentration range of 0–10 mg/mL with a detection limit of 0.06 mg/mL. Due to the advantages of optofluidic structure, the volume of the detection solution could be as low as few tens of nanoliters, and the time to replace and detect the solution only took a few seconds. In addition, the laser sensor realized label-free DNA hybridization detection through surface functionalization, and could detect 1 μM target DNA solution with high specificity. This sensing device had great potential for small volume and low concentration sample detection in the biochemical field.

介绍了一种采用飞秒激光微加工技术制造的光纤内光流体迈克尔逊干涉仪。干涉仪结构由具有两个芯和一个微通道的特殊光纤制备。一个纤芯连接到单模光纤 (SMF) 的纤芯，用作微通道内壁上的传感臂，另一个纤芯用作参考臂，连接到飞秒激光加工引入的光波导。通过与环形腔激光器相结合，可以提高干涉仪的检测限（DL）。激光传感器呈现出高线性响应，折射率 (RI) 灵敏度为 1039.77 nm/RIU，计算的 DL 可低至 1.675 × 10 ^-5里乌。然后，传感器测量片剂中不同浓度的维生素 C，浓度范围为 0-10 mg/mL，检测限为 0.06 mg/mL。由于光流控结构的优势，检测溶液的体积可以低至几十纳升，更换和检测溶液的时间只需几秒钟。此外，激光传感器通过表面功能化实现了无标记DNA杂交检测，可对1 μM目标DNA溶液进行高特异性检测。该传感装置在生化领域小体积、低浓度样品检测方面具有巨大潜力。