Low-dead volume microfluidic circuit and methods

• US 8,230,744 B2
• Filed: 05/06/2009
• Issued: 07/31/2012
• Est. Priority Date: 05/06/2009
• Status: Active Grant

• Current Assignee: CeQur SA
• Original Assignee: CeQur SA
• Inventors: Gravesen, Peter, Arndt, Heiko
• Primary Examiner(s): THOMPSON, JEWEL VERGIE
• Application Number:
  US12/436,365
• Publication Number:
  US 20100281990A1
• Time in Patent Office: 1,182 Days
• Field of Search: 737/15, 73/405, 600/347
• US Class Current: 73/715
• CPC Class Codes: A61M 2005/1405 Patient controlled analgesia [PCA]
• CPC Class Codes: A61M 2005/14252 with needle insertion means
• CPC Class Codes: A61M 2206/20 having means for promoting or enhancing the flow, actively or passively
• CPC Class Codes: A61M 5/141 with capillaries for restricting fluid flow
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps
• CPC Class Codes: A61M 5/14248 of the skin patch type
• CPC Class Codes: A61M 5/152 pressurised by contraction of elastic reservoirs containers for dispensing contents by contraction of an elastic bag provided therein, in general B65D83/0061
• CPC Class Codes: A61M 5/158 Needles for infusions; Accessories therefor, e.g. for inserting infusion needles, or for holding them on the body
• CPC Class Codes: B01L 2200/0605 Metering of fluids
• CPC Class Codes: B01L 2300/14 Means for pressure control
• CPC Class Codes: B01L 2400/0633 with moving parts
• CPC Class Codes: F04B 19/006 Micropumps F04B43/043 and F04B43/095 take precedence
• CPC Class Codes: G01L 19/0007 Fluidic connecting means
• CPC Class Codes: Y10T 137/0402 Cleaning, repairing, or assembling

Abstract

A method is described for reducing a dead volume of a microfluidic circuit that includes, in one embodiment, a reservoir, an outlet, and a microfluidic flowpath fluidly connecting the reservoir and the outlet. The method includes providing a microfluidic flow component between the reservoir and the outlet for performing a function and in fluidic communication with the microfluidic flowpath, wherein the microfluidic flow component includes a total volume including a working volume and a dead volume. The working volume is a volume necessary for the microfluidic flow component to perform the function and the dead volume is a volume unnecessary for the microfluidic flow component to perform the function. The method includes configuring at least one of the reservoir, the microfluidic flowpath, and the microfluidic flow component to reduce the dead volume, such that the working volume of the component is substantially the same as the total volume.

Claims

1. A method for reducing a dead volume of a microfluidic circuit comprising a reservoir, an outlet, and a microfluidic flowpath fluidly connecting the reservoir and the outlet, the method comprising:

providing a microfluidic flow component located between the reservoir and the outlet for performing a function and in fluidic communication with the microfluidic flowpath,

wherein the microfluidic flow component comprises a total volume comprising a working volume and a dead volume, wherein the working volume comprises a volume necessary for the microfluidic flow component to perform the function and the dead volume comprises a volume unnecessary for the microfluidic flow component to perform the function; and

configuring at least one of the reservoir, the microfluidic flowpath, and the microfluidic flow component to reduce the dead volume, such that the working volume is substantially the same as the total volume.

2. The method of claim 1, wherein the configuring step results in the total volume being substantially the same as the working volume.

3. The method of claim 1, wherein the microfluidic flow component comprises at least one of a flowpath transition, a valve, a constant-volume fluid chamber, a pressure sensor, and a variable-volume fluid chamber.

4. The method of claim 3, wherein the microfluidic flow component comprises a constant-volume fluid chamber defining an internal chamber, a chamber inlet in fluidic communication with the internal chamber, and a chamber outlet in fluidic communication with the internal chamber, wherein the internal chamber comprises the total volume, and wherein the configuring step comprises:

providing a volume reduction element within the internal chamber so as to define a reduced volume flow path from the chamber inlet to the chamber outlet, wherein the reduced volume flow path substantially defines the working volume.

5. The method of claim 4, wherein the working volume comprises about 14% of the total volume prior to the configuring step.

6. The method of claim 3 wherein the microfluidic flow component comprises a valve, the valve comprising a housing defining a valve chamber therein, the valve chamber defined at least in part by a sidewall and a valve seat, the valve seat comprising at least one of a base surface and a raised plateau defining a valve inlet and a plateau wall extending from the raised plateau to the base surface, the base surface defining a valve outlet, and a seal member having a surface corresponding substantially to the sidewall and the raised plateau, and wherein the configuring step comprises:

providing a volume reduction element within the valve chamber such that the seal member corresponds substantially to the base surface and the plateau wall.

7. The method of claim 6, wherein the working volume comprises about 0% of the total volume prior to the configuring step.

8. The method of claim 3 wherein the microfluidic flow component comprises a pressure sensor comprising a flexible membrane and a base surface disposed in opposition to the flexible membrane, wherein a volume located between the flexible membrane and the base surface defines the total volume, and wherein the configuring step comprises:

providing two raised structures disposed between the flexible membrane and the base surface, wherein top surfaces of the raised structures are proximate to, but not in contact with, the flexible membrane, wherein the side surfaces of the raised structures intersect the base surface, and wherein the side surfaces of the raised structures, the base surface, and the flexible membrane at least partially define a flow channel, and wherein the flow channel defines the working volume.

9. The method of claim 8, wherein the working volume comprises about 40% of the total volume prior to the configuring step.

10. The method of claim 3, wherein the variable-volume fluid chamber comprises a base surface, an inlet, and a separate outlet, and wherein the configuring step comprises:

providing a flexible membrane wherein the base surface and the membrane define a first volume when the membrane is proximate the base surface, wherein the base surface and the membrane define a second volume when the membrane is displaced by a fluid pressure away from the base surface, and wherein the membrane is biased towards the base surface.

11. The method of claim 10, wherein the working volume comprises about 5% of the total volume prior to the configuring step.