Concentration measurement of coloured solution using optofluidic approach

Abstract

In analytical process, measurement of concentration of solution based on colorimetric sensing is normally performed using commercial devices such as colorimeter and spectrophotometer. This approach has several disadvantages such as involving a large volume of reagent and analyte during testing and measurement, unextendible and expensive. Such problem can be solved by replicating its function using a simple optofluidic device with capability of carrying out colorimetric testing with low volume of analyte and reagent. Other benefits of optofluidic devices platforms includes ability to be expanded for automated sensing and mixing for various analytical based reaction. The measurement device works based on the absorbance of absorbance of light, which is related to Beer-Lambert law principles with LED and photodiode as its main optical components. The samples were prepared for concentration ranges between 0.2 to 2.0 M for testing. As a result, it is observed that these concentrations produce a linear voltage calibration curve with correlation coefficient, R2 equal to 0.9944. By using the obtained calibration curve, the final absorbance calculation gives an acceptable linear absorbance concentration with R2 equal to 0.9751 for the tested samples. As a conclusion, these microfluidic platforms not only have a good measurement performance, but also have advantages in terms of its portability and have potential to be implemented for real time application.