Method and apparatus for controlling fluid flow rate in a microfluidic circuit

The method of claim 10, wherein the second fluid is configured to insulate the first fluid from contact with an internal surface of the microfluidic channel.

A method of controlling a flow of a fluid sample, comprising:

• providing a first fluid as a flow in a microfluidic channel, the first fluid having an unknown or variable viscosity;
• and
• sheathing the first fluid with a second fluid having a known viscosity, such that the first fluid has a flow rate that is substantially equal to a flow rate of the second fluid at the interface with the first fluid.

An apparatus for controlling a flow of a fluid samples in a microfluidic channel, comprising:

• a first fluid, provided as a flow in the microfluidic channel;
• a second fluid, provided as a flow between an internal surface of the channel and the first fluid, the second fluid having a known viscosity tailored to achieve a constant flow rate at a the interface with the first fluid, such that the first fluid achieves substantially the constant flow rate independent of a viscosity associated with the first fluid.

A method of controlling a flow of a fluid sample, comprising:

• providing a first fluid as a flow in a microfluidic channel;
• and
• providing a second fluid as a flow in the microfluidic channel between the first fluid and an internal surface of the channel, the second fluid having a known viscosity, such that the first fluid has a flow rate that is substantially equal to a flow rate of the second fluid at the interface with the first fluid.

A system for performing a microfluidic process, comprising:

• a microfluidic channel, having a first inlet for receiving a first fluid flow and a second inlet for receiving a second fluid flow in between the first fluid flow and an internal surface of the channel, the second fluid having a viscosity that is selected for achieving a particular, constant flow rate at the interface with the first fluid, such that the first fluid flow achieves a flow rate that is substantially equal to the flow rate of the second fluid at the interface with the first fluid.

A method of controlling a flow of a fluid sample, comprising:

• injecting a first fluid into a microfluidic channel;
• and
• injecting a second fluid into the channel adjacent to the first fluid, the second fluid having a known viscosity, such that the first fluid has a flow rate that is substantially equal to a flow rate of the second fluid at the interface between the first and second fluid.

A method of controlling a flow of a fluid sample, comprising:

• providing a first fluid as a flow in a microfluidic channel, the first fluid containing non-dissolved particles that are susceptible to forces which affect the flow of the first fluid;
• and
• sheathing the first fluid within a second fluid having a controlled flow, so as to substantially insulate the first fluid from the forces.

A method of controlling a flow of a fluid sample, comprising:

• providing a first fluid as a flow in a microfluidic channel, the first fluid containing non-dissolved particles that are susceptible to forces which affect the flow of said non-dissolved particles within said microfluidic channel;
• and
• sheathing the first fluid within a second fluid having a controlled flow, so as to substantially insulate said first fluid from the forces.

A method of controlling a flow of a fluid sample, comprising:

• providing a first fluid as a flow in a microfluidic channel, the first fluid containing non-dissolved particles that are susceptible to forces which are substantially perpendicular to the direction of flow within said microfluidic channel;
• and
• sheathing the first fluid within a second fluid having a controlled flow, so as to substantially insulate said first fluid from the forces.