# US 10,307,756 B2 · Capillary junction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,307,756 B2 - Document ID: US10307756B2 - Status: Granted - Kind: B2 - Application number: 15/928,215 - Filed: 2018-03-22 - Published: 2018-07-26 - Granted: 2019-06-04 - Earliest claimed: 2015-06-19 - Assignees: Biosurfit, S.A. - Applicants: Biosurfit, S.A. - Inventors: Ricardo Manuel Marques Caleiro Cabeça; André Do Rosário Magalhães; Andreia Andrade Dos Santos; Sandra Cristina Sarmento Donato Dos Santos E Silva; João Manuel De Oliveira Garcia Da Fonseca - Web page: https://patentgrep.com/patent/US10307756B2 ## CPC - B01L 3/502723: {characterised by venting arrangements} - B01L 3/50273: {characterised by the means or forces applied to move the fluids} - B01L 3/502746: {characterised by the means for controlling flow resistance, e.g. flow controllers, baffles or throttle valves} - F04B 19/006: {Micropumps (F04B43/043 and F04B43/095 take precedence)} - B01L 2200/0621: Control of the sequence of chambers filled or emptied - B01L 2300/0816: Cards, e.g. flat sample carriers usually with flow in two horizontal directions - B01L 2300/0864: comprising only one inlet and multiple receiving wells, e.g. for separation, splitting - B01L 2400/0406: capillary forces - B01L 2400/0688: surface tension valves, capillary stop, capillary break - B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE - F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F) ## Abstract A microfluidic device with reduced risk of bubble formation at a capillary junction between two conduits is provided. In some embodiments, the microfluidic device comprises a supply reservoir, a first conduit and a second conduit. The first conduit is configured such that liquid flows by capillary effect from the supply reservoir into the first conduit. The second conduit is connected to the first conduit through an opening in a wall of the first conduit and is configured such that liquid flows from the first conduit to the second conduit by capillary effect. A width of the second conduit, along a direction of liquid flow in the first conduit, is greater than a depth of the second conduit and a depth of the second conduit is less than a depth of the first conduit. ## Claims ### Claim 1 A microfluidic device comprising: a supply reservoir; a first vented conduit in fluidic communication with the supply reservoir such that liquid flows by capillary effect from the supply reservoir into the first conduit; and a second unvented conduit connected to the first vented conduit through an opening in a wall of the first vented conduit and configured such that liquid flows from the first vented conduit to the second unvented conduit by capillary effect; wherein a width of the second unvented conduit, along a direction of liquid flow in the first vented conduit, is greater than a depth of the second unvented conduit; and wherein the depth of the second unvented conduit is less than a depth of the first vented conduit. ### Claim 2 (depends on 1) A device as claimed in claim 1, further comprising: a first vent structure comprising an air channel connecting the first vented conduit to the supply reservoir, the first vent structure enabling gas in the first vented conduit displaced by flow of liquid from the supply reservoir into the first vented conduit to escape from the first vented conduit and into the supply reservoir. ### Claim 3 (depends on 1) A device as claimed in claim 1, wherein a ratio of a depth of the first vented conduit upstream of a junction between the first vented conduit and second unvented conduit to the depth of the second unvented conduit is greater than or equal to 3. ### Claim 4 (depends on 1) A device as claimed in claim 1, wherein the first vented conduit comprises a surface tension barrier downstream of a junction between the first vented conduit and second unvented conduit. ### Claim 5 (depends on 1) A device as claimed in claim 1, wherein a portion of the first vented conduit downstream of a junction between the first vented conduit and second unvented conduit has a transverse dimension greater than a depth of the first vented conduit upstream of the junction between the first vented conduit and second unvented conduit. ### Claim 6 (depends on 5) A device as claimed in claim 5, wherein a ratio of the depth of the first vented conduit upstream of the junction between the first vented conduit and second unvented conduit to a depth of the aforesaid portion of the first vented conduit downstream of the junction between the first vented conduit and second unvented conduit is less than or equal to 0.75. ### Claim 7 (depends on 1) A device as claimed in claim 1, wherein a portion of the first vented conduit downstream of a junction between the first vented conduit and second unvented conduit has a depth greater than a depth of the first vented conduit upstream of the junction between the first vented conduit and second unvented conduit. ### Claim 8 (depends on 1) A device as claimed in claim 1, wherein a depth decrease from the first vented conduit to the second unvented conduit is configured as a step. ### Claim 9 (depends on 1) A device as claimed in claim 1, wherein a ratio of the width of the second unvented conduit to the depth of the second unvented conduit is greater than or equal to 42.5. ### Claim 10 (depends on 1) A device as claimed in claim 1, wherein at least one of the first vented conduit and second unvented conduit contains a dry reagent. ### Claim 11 (depends on 1) A device as claimed in claim 1, wherein the second unvented conduit is configured as a detection conduit to allow liquid to be imaged as it flows through the second unvented conduit. ### Claim 12 (depends on 11) A device as claimed in claim 11, wherein a wall of the second unvented conduit is substantially transparent. ### Claim 13 (depends on 1) A device as claimed in claim 1, wherein the second unvented conduit is substantially perpendicular to the first vented conduit.