A portable apparatus for extracting and concentrating bioagents within a fluid medium includes a container with sample solution inlet port and traveling wave grids patterned on surfaces of the container. The traveling wave grids cause bioagents to migrate to a specified surface within the container and then to an extraction port. The traveling wave grids include a substrate, across which extend a collection of closely spaced and parallel electrically conductive electrodes, and a collection of buses providing electrical communication with the collection of conductive electrodes. A voltage controller provides a multiphase electrical signal to the collection of buses and electrodes of the traveling wave grids.