A colorimetric microfluidic sensor made by a simple instrumental-free prototyping process for sensitive quantitation of copper

A simple, cost-effective, instrumental-free prototyping process has been developed for fabricating flexible, multilayer colorimetric microfluidic sensor. A hand-hold punch was used to make microfluidic sensor pattern with no use of any expensive instruments (laser cutter, cutting plotter, screen printer, wax printer, etc.). Colorimetric analysis was carried out using a smartphone camera as a reader. Sensitive quantitation of copper has been demonstrated on the developed sensor under the optimal parameters. In the presence of copper ion, the Blue channel color values decreased with increasing the Cu2+ concentration. The Blue channel color intensity was linear with the concentration of Cu2+ in the range from 0 to 30mg/L with a detection limit of 0.096mg/L (3 sigma). The developed microfluidic sensor possesses good selectivity, satisfying reproducibility and high recoveries in tap water. Furthermore, through changing hole punch with different hole shape and hole numbers, it is extremely easy to produce microfluidic sensors with different design in quantity at low cost. What's more, the developed sensor could be easily extended to detect other single analyte or multiple analytes, showing promising practical applications in environmental analysis.