Inkjet printing on transparency films for reagent storage with polyester–toner microdevices

The use of overhead transparencies as substrates for the fabrication of microfluidic devices brings new capabilities in the creation of fully-integrated systems. Here, we describe a reagent storage method through inkjet printing that is complementary to the simple print, cut and laminate (PCL) fabrication technique, which already incorporates printing toner onto commercial off-the-shelf materials for fabrication of polyester–toner microdevices. With the surface of the polyester film dramatically different than paper, substrate optimization was required to increase printability without incorporating additional substrate-coating steps. Functionality for chemical sensing devices, operated centrifugally here, was demonstrated through standard human serum albumin analysis. Quantitative results were obtained through image analysis using a desktop scanner to determine color change in the presence of various total protein and albumin concentrations. Printed devices exhibited a shelf life of at least two months with no loss in activity, resulting in a relative standard deviation of 0.652% for total protein analysis.