Lab-on-a-chip (LoC) technologies are nominated to revolutionize chemical and bio-chemical analysis. Although their great potential, they have not reach the consumer grade market, due to a lack of truly enabled functionality compared to current analytical methods. This works focuses on performing absorbance detection on LoC devices, by an easy to implement set-up. The present work is enclosed in a project which aims to combine, low-price absorption detection, low-cost materials and fast prototyping/fabrication method for developing an affordable and portable diagnostic tool based on enzymatic immunoassays. The obtained results are satisfactory, due to the obtained sensitivity, an order of magnitude higher than a standard microplate reader.