Paper-Based Microfluidics Goes Digital
Due to the passive nature of traditional paper-based microfluidic devices, high precision control of certain parts of multi-step assays can be difficult to acheive. Researchers R. Fobel et al. at the University of Toronto recently published an article in Advanced Materials reporting the invention of a digital paper-based microfluidic device with high precision control of multistep processes on paper.
Digital microfluidics (DMF) is a technology in which nano-to-microliter sized drops are manipulated on an array of electrodes using electric fields. The electrostatic forces can move, split, merge, and dispense drops to and from reservoirs within a device without the use of active pumps or moving parts. Paper-based DMF devices are fabricated by inkjet printing silver electrodes and reservoirs onto smooth paper surfaces. To test the ability of the novel device to perform a multistep process, the group used one of the chips to perform a serial dilution and create a calibration curve for the chemiliuminescence assay of horseradish peroxidase (HRP) mixed with luminol and hydrogen peroxide. Overall, very interesting applications may come from combining these methods with the traditional paper-based diagnostic assay, especially in steps which would be difficult to perform with solely capillary-driven flow.
Demonstration of digital microfluidics on a paper-based device. Fobel, R., Kirby, A. E., Ng, A. H. C., Farnood, R. R. and Wheeler, A. R. (2014), Paper Microfluidics Goes Digital. Adv. Mater.. doi: 10.1002/adma.201305168. © 2014 Advanced Materials.