Future Industries Institute, STEM, University of South Australia, Mawson Lakes, SA 5095, Australia.
ARC Research Hub for Integrated Devices for End-User Analysis at Low-Levels (IDEAL), Future Industries Institute, STEM, University of South Australia, Mawson Lakes, SA 5095, Australia.
Sensors (Basel). 2022 May 29;22(11):4135. doi: 10.3390/s22114135.
The rapid development of optofluidic technologies in recent years has seen the need for sensing platforms with ease-of-use, simple sample manipulation, and high performance and sensitivity. Herein, an integrated optofluidic sensor consisting of a pillar array-based open microfluidic chip and caged dye-doped whispering gallery mode microspheres is demonstrated and shown to have potential for simple real-time monitoring of liquids. The open microfluidic chip allows for the wicking of a thin film of liquid across an open surface with subsequent evaporation-driven flow enabling continuous passive flow for sampling. The active dye-doped whispering gallery mode microspheres placed between pillars, avoid the use of cumbersome fibre tapers to couple light to the resonators as is required for passive microspheres. The performance of this integrated sensor is demonstrated using glucose solutions (0.05-0.3 g/mL) and the sensor response is shown to be dynamic and reversible. The sensor achieves a refractive index sensitivity of 40 nm/RIU, with Q-factors of ~5 × 10 indicating a detection limit of ~3 × 10 RIU (20 mg/mL glucose). Further enhancement of the detection limit is expected by increasing the microsphere Q-factor using high-index materials for the resonators, or alternatively, inducing lasing. The integrated sensors are expected to have significant potential for a host of downstream applications, particularly relating to point-of-care diagnostics.
近年来，光流控技术迅速发展，因此需要具有易用性、简单的样品处理、高性能和高灵敏度的传感平台。在此，展示了一种由基于立柱阵列的开放式微流控芯片和笼状染料掺杂 whispering gallery 模式微球组成的集成光流控传感器，并表明其具有简单实时监测液体的潜力。开放式微流控芯片允许在开放表面上吸润一层薄的液体膜，随后通过蒸发驱动的流动实现连续的被动流动以进行采样。放置在立柱之间的活性染料掺杂 whispering gallery 模式微球避免了使用繁琐的光纤锥将光耦合到谐振器中，这是被动微球所必需的。该集成传感器的性能使用葡萄糖溶液（0.05-0.3 g/mL）进行了演示，并且表明传感器响应是动态和可逆的。传感器实现了约 40nm/RIU 的折射率灵敏度，Q 因子约为 5×10，表明检测限约为 3×10 RIU（~20mg/mL 葡萄糖）。通过使用高折射率材料提高谐振器的微球 Q 因子，或者通过诱导激光，预计可以进一步提高检测限。集成传感器有望在许多下游应用中具有重要的潜力，特别是在即时诊断方面。
