Spontaneous diffusiophoretic separation in paper-based microfluidic device

Microfluidic paper-based analytical devices (mu PADs) for separating particles have been playing a key role for point-of-care diagnostics in the area of remote settings. While splendid separation methods using mu PADs have been explosively developed, they still require external devices inducing external field. In this work, the spontaneous separation method in mu PADs was suggested by leveraging convective flow (the imbibition of paper and nanoporous medium) and diffusiophoresis by ion exchange medium. Especially, the paper's fast imbibition was utilized as driving particles at the first stage, which results in fast overall processing in contrast to the spontaneous separation method of microfluidic chip integrated with only ion exchange medium. Therefore, our novel spontaneous selective preconcentration method based on mu PADs would have key potential to be used in portable point-of-care devices in remote settings.