The ability to sense dynamic biochemical reactions and material processes is particularly crucial for a wide range of applications, such as early-stage disease diagnosis and biomedicine development. Optical microcavities-based label-free biosensors are renowned for ultrahigh sensitivities, and the detection limit has reached a single nanoparticle/molecule level. In particular, a microbubble resonator combined with an ultrahigh quality factor (Q) and inherent microfluidic channel is an intriguing platform for optical biosensing in an aqueous environment. In this work, an ultrahigh Q microbubble resonator-based sensor is used to characterize dynamic phase transition of a thermosensitive hydrogel. Experimentally, by monitoring resonance wavelength shift and linewidth broadening, we (for the first time to our knowledge) reveal that the refractive index is increased and light scattering is enhanced simultaneously during the hydrogel hydrophobic transition process. The platform demonstrated here paves the way to microfluidical biochemical dynamic detection and can be further adapted to investigating single-molecule kinetics.

中文翻译：

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超高Q微泡谐振器中水凝胶凝胶-溶胶转变的实时监测

感知动态生化反应和材料过程的能力对于广泛的应用尤其重要，例如早期疾病诊断和生物医学开发。基于光学微腔的无标记生物传感器以超高灵敏度着称，检测限已达到单个纳米颗粒/分子水平。特别是，结合超高品质因子 (Q) 和固有微流体通道的微泡谐振器是水性环境中光学生物传感的一个有趣平台。在这项工作中，基于超高 Q 微泡谐振器的传感器用于表征热敏水凝胶的动态相变。实验上，通过监测共振波长偏移和线宽展宽，我们（据我们所知第一次）揭示了在水凝胶疏水转变过程中折射率增加和光散射同时增强。这里展示的平台为微流体生化动态检测铺平了道路，可以进一步适应研究单分子动力学。