Ferro-microfluidic device for pathogen detection

In a previous work, we demonstrated that traveling wave excitations from integrated electrodes can continuously pump magnetic liquids within a microfluidic channel [1]. The optimum excitation frequency of this pumping is strongly dependent on the hydrodynamic size of the magnetic nanoparticles, and the effect can be used to detect whenever a molecule or pathogen binds to the magnetic nanoparticles within a ferrofluid. Here, we demonstrate the bio-functionality and pathogen detection capability of a ferrofluid comprised of cobalt-ferrite-silica nanoparticles through the use of biotinylated genetically engineered peptides for inorganics (GEPI’s) [2]. These biotinylated GEPI’s are specifically engineered to attach to the silica surface of the magnetic nanoparticles. Binding of streptavidin to the biotinylated GEPI’s on the surface of the magnetic nanoparticles shifts the optimum pumping frequency by an amount that corresponds to the increase in the hydrodynamic size of the nanoparticle. The combination of GEPI-enhanced ferrofluids with integrated microfluidic devices finally enables the development of highly sensitive, portable and cheap pathogen sensor chips.