Abstract: A method of controlling fluid flow within a microfluidic circuit using external valves and pumps connected to the circuit is disclosed. The external valves and pumps, which are not a part of the microfluidic substrate, control fluid pumping pressure and the displacement of air out of the fluid circuit as fluid enters into the circuit. If a valve is closed, air cannot be displaced out of circuit, which creates a pneumatic barrier that prevents fluid from advancing within the circuit (under normal operating pressures). Applications of this method of fluid control are explained.

Abstract: A method and system are disclosed for manipulating the flow of gases into and out of a microfluidic circuit to regulate pressure within the circuit or to provide for the delivery of gases to or removal of gases from the circuit. Pressure within the microfluidic circuit may be increased or decreased to modify physical or chemical properties of fluid within the circuit, or to modify reaction kinetics. Gaseous reactants may be added to the circuit, and reaction products or excess reactant gases may be removed the circuit according to the invention. Warm or cool air or other gas may be flowed over liquid reactants within the circuit to perform a warming or cooling function. Various biochemical reactions or processes, including for example polymerase chain reaction (PCR) and ligand-receptor binding, may be performed with the use of the inventive method and system.

Abstract: Methods of controlling fluid flow through microchannels by use of passive valves or stopping means in the microchannels is presented. The passive valves act as pressure barriers impeding flow of solution past the stopping means until enough force is built up to overcome the force of the pressure barrier. Well planned use of such stopping means acting as passive valves allows the flow of fluids through microchannels to be regulated so as to allow fluids to be mixed or diluted after being introduced via a single channel, or to be split into multiple channels without the need for individual pipetting. Flow through the multiple channels can be regulated to allow a series of sister wells or chambers to all fill prior to the fluid flowing beyond any one of the sister wells or chambers. The filling of sister wells or chambers in this manner allows all wells or chambers to undergo reactions in unison. The use of air ducts to prevent trapping of air in the microchannels is also presented.

Abstract: Methods and apparatus for controlling fluid flow through microchannels by use of passive valves or stopping means comprised of abrupt microchannel widenings in the microchannels are presented. Such passive fluid flow barriers create pressure barriers impeding flow of solution past the passive fluid flow barriers until enough force is built up to overcome the force of the pressure barrier. Use of such stopping means acting as passive barriers or valves allows the flow of fluids through microchannels to be regulated so as to allow fluids to be mixed or diluted after being introduced via a single channel, or to be split into multiple channels without the need for individual pipetting. Flow through the multiple channels can be regulated to allow a series of sister wells or chambers to all fill prior to the fluid flowing beyond any one of the sister wells or chambers. The filling of sister wells or chambers in this manner allows all wells or chambers to undergo reactions in unison.

Abstract: A method and system are disclosed for manipulating the flow of gases into and out of a microfluidic circuit to regulate pressure within the circuit or to provide for the delivery of gases to or removal of gases from the circuit. Pressure within the microfluidic circuit may be increased or decreased to modify physical or chemical properties of fluid within the circuit, or to modify reaction kinetics. Gaseous reactants may be added to the circuit, and reaction products or excess reactant gases may be removed the circuit according to the invention. Warm or cool air or other gas may be flowed over liquid reactants within the circuit to perform a warming or cooling function. Various biochemical reactions or processes, including for example polymerase chain reaction (PCR) and ligand-receptor binding, may be performed with the use of the inventive method and system.

Abstract: Methods of controlling fluid flow through microchannels by use of passive valves or stopping means in the microchannels is presented. The passive valves act as pressure barriers impeding flow of solution past the stopping means until enough force is built up to overcome the force of the pressure barrier. Well planned use of such stopping means acting as passive valves allows the flow of fluids through microchannels to be regulated so as to allow fluids to be mixed or diluted after being introduced via a single channel, or to be split into multiple channels without the need for individual pipetting. Flow through the multiple channels can be regulated to allow a series of sister wells or chambers to all fill prior to the fluid flowing beyond any one of the sister wells or chambers. The filling of sister wells or chambers in this manner allows all wells or chambers to undergo reactions in unison. The use of air ducts to prevent trapping of air in the microchannels is also presented.

Abstract: A method of controlling fluid flow within a microfluidic circuit using external valves and pumps connected to the circuit is disclosed. The external valves and pumps, which are not a part of the microfluidic substrate, control fluid pumping pressure and the displacement of air out of the fluid circuit as fluid enters into the circuit. If a valve is closed, air cannot be displaced out of circuit, which creates a pneumatic barrier that prevents fluid from advancing within the circuit (under normal operating pressures). Applications of this method of fluid control are explained.

Abstract: Methods of controlling fluid flow through microchannels by use of passive valves or stopping means in the microchannels is presented. The passive valves act as pressure barriers impeding flow of solution past the stopping means until enough force is built up to overcome the force of the pressure barrier. Well planned use of such stopping means acting as passive valves allows the flow of fluids through microchannels to be regulated so as to allow fluids to be mixed or diluted after being introduced via a single channel, or to be split into multiple channels without the need for individual pipetting. Flow through the multiple channels can be regulated to allow a series of sister wells or chambers to all fill prior to the fluid flowing beyond any one of the sister wells or chambers. The filling of sister wells or chambers in this manner allows all wells or chambers to undergo reactions in unison. The use of air ducts to prevent trapping of air in the microchannels is also presented.