Fluidic Manipulation of a Paper Origami for Oil Quality Testing

We designed and fabricated a novel miniaturized multiplex origami paper device for edible oil quality testing. The device consists of 'fin-like' structures, which are designed for accurately manipulating fluid volumes and depositing chemical reagents, to simultaneously evaluate the quality of oils using a colorimetric method. The multiplexing was optimized by fluidic manipulation on the arms of the fins, which functioned as passive valves. This optimization allowed for improved control and regulation of the passive fluid movement within the device. To confirm validity of the results, we also developed a singleplex vertical paper device and conducted peroxide tests on seven different oils. The device was used to titrate the oil samples by manipulating the volume of the titrant, which allowed for the determination of the peroxide value. The obtained brown color gradient and the corresponding peroxide value from the titration process were then correlated to assess the quality of the oil. The implementation of the origami device offered a rapid, efficient, and cost-effective platform for testing the quality of edible oils in the agro-food industry. With the device, the quality of oil can be assessed by observing the brown color gradient, which serves as an indication of the peroxide value. The device allows for simultaneous testing of peroxide levels in edible oils, making it a valuable tool for multiplex testing purposes. In the future, the developed passive assay can be modified for testing pathogens in human body fluids, as a point of care diagnostic tool.