Abstract: Many hand-held diagnostics are limited in their functionality due to the challenging physics associated with small dimensional systems. An example of this is capillary forces in hydrophilic systems, such as the tight retention of liquid passing through a small pore filtration membrane, or capillary force driven microfluidics where, to keep liquid flowing the dimensions of the system become so small that the flow rates are too low to be useful, or the manufacturing of such devices becomes uneconomical. This disclosure details methods to ‘reset’ the capillary force condition to avoid the requirement of transient pressure spikes associated with the breakthrough pressure of small pore membranes, and avoid the necessity of extremely small microfluidic channels, which can be useful in applications such as filtration of whole blood to plasma using only suction pressure or passive capillary pressure.

Abstract: Many hand-held diagnostics are limited in their functionality due to the challenging physics associated with small dimensional systems. An example of this is capillary forces in hydrophilic systems, such as the tight retention of liquid passing through a small pore filtration membrane, or capillary force driven microfluidics where, to keep liquid flowing the dimensions of the system become so small that the flow rates are too low to be useful, or the manufacturing of such devices becomes uneconomical. This disclosure details methods to ‘reset’ the capillary force condition to avoid the requirement of transient pressure spikes associated with the breakthrough pressure of small pore membranes, and avoid the necessity of extremely small microfluidic channels, which can be useful in applications such as filtration of whole blood to plasma using only suction pressure or passive capillary pressure.