Filter media having an optimized gradient

A filter media having a gradient in mean pore size across at least a portion of the thickness of the filter media, wherein the gradient is represented by an exponential function fit to four numerical values of the mean pore size determined at different points across at least the portion of the thickness of the filter media, the exponential function having the form:

• mean pore size(x)=a*exp(k*x)
• wherein x corresponds to a location along the thickness of the portion of the filter media and is normalized to have a value greater than or equal to 0 and less than or equal to 1, and
• wherein k is greater than or equal to 0.1 and less than or equal to 1.75;
• wherein a is greater than or equal to 0.1 microns and less than or equal to 100 microns;
• wherein the exponential function is determined using a least squares linear regression model;
• and
• wherein a coefficient of determination of the exponential function is greater than or equal to about 0.9.

A filter media having a gradient in mean pore size across at least a portion of the thickness of the filter media, wherein the gradient is represented by an exponential function fit to at least four numerical values of the mean pore size determined at different points across at least the portion of the thickness of the filter media, the exponential function having the form:

• mean pore size(x)=a*exp(k*x)
• wherein x corresponds to a location along the thickness of the portion of the filter media and is normalized to have a value greater than or equal to 0 and less than or equal to 1, and
• wherein k is greater than or equal to 0.1 and less than or equal to 1.75;
• wherein a is greater than or equal to 0.1 microns and less than or equal to 100 microns;
• wherein the exponential function is determined using a least squares linear regression model;
• wherein a coefficient of determination of the exponential function is greater than or equal to about 0.7;
• and
• wherein the coefficient of determination of the exponential function is greater than all coefficient of determinations for linear functions fit to the at least four numerical values of the mean pore size using the least squares linear regression model.