Spiral microfluidic devices have been widely used as concentrators and separators for sample preparation. The position of particle focusing is mainly determined by the confinement ratio (CR) which is a ratio of particle diameter to channel hydraulic diameter - smaller channel dimensions enable smaller particles to be focused on the inner wall of the spiral. These devices are widely used as separators for large CR particles but cannot effectively separate small CR particles due to relatively smaller focusing force. To efficiently separate a wider range of CR particles, some devices have two inlets with additional sheath flow. The introduction of two inlets allows the device to achieve increased separation distance, resolution and efficiency, but ultimately increases flow complexity and reduces operating flexibility for a closed-loop system. The present invention is multi-dimensional double spiral (MDDS) device that enables concentration and separation of samples using a single inlet configuration to improve separation resolution and efficiency with a wide target size range.