Device and methods using porous media in fluidic devices

An apparatus, comprising:

• a fluidic device having a fluidic channel and a cavity, the fluidic channel having a channel diameter to accommodate a fluid flow and the cavity having an open end in proximity to a surface of the fluidic device, wherein the cavity has a dimension that is substantially greater than the channel diameter and wherein the cavity is in fluid communication with the fluidic channel;
• and
• a porous medium comprising a porous material engaged in the cavity of the fluidic device and having a porosity profile, wherein the porosity profile comprises an inner region having a first porosity and an outer region having a second porosity that differs from the first porosity and wherein the inner region and the outer region are aligned along a common axial reference location.

An apparatus, comprising:

• a fluidic device having a fluidic channel and a cavity, wherein the cavity is in fluid communication with the fluidic channel;
• and
• a porous medium disposed in the cavity of the fluidic device, the porous medium having a non-uniform porosity profile that provides different porosities at different radial displacements from a common reference location along a fluid axis, wherein the non-uniform porosity profile is selected for directing a fluid flow along the fluid axis through the porous medium in proximity to an opening of the fluidic channel to reduce fluid dispersion, wherein the non-uniformity porosity profile comprises a first region of the porous medium at a first radial displacement from the common reference location along the fluid axis having a higher porosity than a second region of the porous material at a second radial displacement from the common reference location along the fluid axis, wherein the first region is in proximity to the opening of the fluidic channel, wherein the second region is remote from the opening of the fluidic channel, and wherein the first region extends from a top surface of the porous medium to a bottom surface of the porous medium.