A short review of spiral microfluidic devices with distinct cross-sectional geometries

The inertial-based spiral microfluidic separation device is the most sought after for a number of medical settings, because of its simplicity, high throughput, and rejection from an external source at a lower cost than other types of devices. Spiral microchannels have shown an optimistic outcome for biological cell manipulations as the hydrodynamic particle–particle interactions in these devices are known to have a significant impact on focusing behavior. There have been a plethora of attempts to decipher the forces and migration principle of particles in these intricate microchannels, but the influence of cross-sectional geometries and its fine control over the dean vortices on effective particle manipulation in optimum microfluidic design is yet to be discussed in detail to the tee. This is the first time to compare dean flow mechanism thereby providing deep insights on distinct cross-sectional areas (rectangular, trapezoidal, hybrid/complex and stair-like) of spiral geometry, biocompatibility and its fabrication methods for effective cell focusing and separation. This study insists on the influence of cross-sectional geometry in spiral separation devices to widen the horizons of the existing applications even though the fabrication of the same is still challenging. The advent of 3D printing and other similar technologies seems promising to address the fabrication issues in the near future. This review enables the researchers to focus on intricate cross sections to tune the dean flow for improving the separation performance which paves the way to a slew of new applications in clinical diagnostics and other research areas in the biomedical field.