Kumar Rahul, Nguyen Hien, Rente Bruno, Tan Christabel, Sun Tong, Grattan Kenneth T V
Department of Electrical and Electronic Engineering, University of London, London EC1V 0HB, UK.
School of Physics, Engineering and Computer Science, University of Hertfordshire, Hatfield AL10 9AB, UK.
Micromachines (Basel). 2022 Jul 30;13(8):1224. doi: 10.3390/mi13081224.
Microfluidics is used in many applications ranging from chemistry, medicine, biology and biomedical research, and the ability to measure pH values in-situ is an important parameter for creating and monitoring environments within a microfluidic chip for many such applications. We present a portable, optical fibre-based sensor for monitoring the pH based on the fluorescent intensity change of an acrylamidofluorescein dye, immobilized on the tip of a multimode optical fibre, and its performance is evaluated in-situ in a microfluidic channel. The sensor showed a sigmoid response over the pH range of 6.0-8.5, with a maximum sensitivity of 0.2/pH in the mid-range at pH 7.5. Following its evaluation, the sensor developed was used in a single microfluidic PDMS channel and its response was monitored for various flow rates within the channel. The results thus obtained showed that the sensor is sufficiently robust and well-suited to be used for measuring the pH value of the flowing liquid in the microchannel, allowing it to be used for a number of practical applications in 'lab-on-a-chip' applications where microfluidics are used. A key feature of the sensor is its simplicity and the ease of integrating the sensor with the microfluidic channel being probed.
微流控技术应用于许多领域，涵盖化学、医学、生物学和生物医学研究等。对于许多此类应用而言，在微流控芯片内原位测量pH值的能力是创建和监测环境的一个重要参数。我们展示了一种基于光纤的便携式传感器，用于基于固定在多模光纤尖端的丙烯酰胺荧光素染料的荧光强度变化来监测pH值，并在微流控通道中原位评估其性能。该传感器在6.0 - 8.5的pH范围内呈现S形响应，在pH 7.5的中间范围具有0.2/pH的最大灵敏度。评估之后，所开发的传感器用于单个微流控聚二甲基硅氧烷（PDMS）通道，并监测其在通道内不同流速下的响应。由此获得的结果表明，该传感器足够坚固，非常适合用于测量微通道中流动液体的pH值，使其能够用于许多使用微流控技术的“芯片实验室”应用中的实际应用。该传感器的一个关键特性是其简单性以及将传感器与被探测的微流控通道集成的便利性。
