For fabrication of microfluidic system glass slides (50 x 25 x 1.1 mm) coated with indium tin oxide (ITO) from Delta Technologies, Ltd. were used as a substrate. The electrodes were made by etching in a solution of FeCl3 as described previously in . First, shape of the electrodes was defined by a kapton tape cut using GCC LaserPro C180II Laser Engraver controlled by a computer program. The tape was used to mask the ITO electrodes during the etching process. The width of the working (WE) and counter electrode (CE) was 8 mm and 10 mm, respectively. Next, the CE was covered with gold using a sputtering deposition method to increase its electrochemical activity. A 5 nm layer of Ti was used under the gold film to promote adhesion. Next, for microchannel fabrication a PDMS (Sylgard 184 Silicone, a two-part poly(dimethylsiloxane) elastomer from Dow Corning) was used. Firstly, a matrix for the channel was designed and printed in polylactic acid (PLA) using 3D printer Ultimaker 2+. Then, a microchannel was made by pouring the monomers of PDMS into the matrix and drying for 90 minutes at 65°C. As a result, a 500 µm wide, 180 µm high, and 2 cm long microchannel was received. Holes for the liquid inlet and outlet, as well as the reference electrode were made in the PDMS. Finally, an optical fiber with the microcavity was installed between WE and CE and the PDMS as shown in Fig. .