Development of a micro opto-fluidic sensor for continuous selective in-line monitoring of electrolytes

The aim of this work is to investigate a fluorescent micro opto-fluidic sensor based on the principle of photo-induced electron transfer (PET). As a first proof-of-principle, a lab setup has been developed using a low crosstalk 1×2 splitter and a glass tube of 3.2 mm diameter. The laser intensity peak and the emission spectrum of Rhodamine B have been recorded using a spectrometer at 530 nm and 580 nm respectively. As a next step, a micro opto-fluidic device with integrated optical fiber with a core diameter of 50 µm is fabricated using soft lithography technique. Two different designs have been investigated for their optical performances. The influence of flow rate on the sensitivity of the device is measured by varying the flow rate from 0 to 10000 µl/min and plotting it against ratio of the peak intensity of laser and Rhodamine B emission spectrum. It is noticed that, changing the flow rate from still to a flow rate of 300 µL/min the intensity reduces exponentially (~ 84%) and from 300 µL/min till 600 µL/min it reduces gradually (~ 40%) and becomes stable after 600 µL/min onwards.