Systems and methods for particle focusing in microchannels
Inventors
Aguirre, Gerson • Xia, Zheng • Kamalakshakurup, Gopakumar
Assignees
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Publication Number
US-11331670-B2
Publication Date
2022-05-17
Expiration Date
Abstract
A microfluidic system configured to focus particles suspended in a fluid. One general aspect includes a microfluidic system comprising one or more substrates and a focusing channel formed in the one or more substrates and spanning a length from an inlet to an outlet for receiving a flow of particles suspended in fluid, wherein the particles have a diameter (a) and the focusing channel has a hydraulic diameter (dh).
Core Innovation
The invention relates to a microfluidic system and a method for focusing sperm cells suspended in a fluid for flow-cytometry-based semen sexing. A focusing channel formed in one or more substrates receives a flow of sperm cells suspended in the fluid and spans a length from an inlet to an outlet.
The focusing is defined using geometric relationships between a cell diameter (a) and a hydraulic diameter (Dh) of the channel, together with a curvature-related critical parameter (r) defined by 2r a^2 / Dh^3. The focusing channel is dimensioned such that a ratio of the cell diameter to the hydraulic diameter (a/Dh) is between about 0.03 and about 0.06, and the ratio of curvature (critical parameter “r”) to the hydraulic diameter (Dh), defined by 2r a^2 / Dh^3, is less than about 0.03.
Within these constraints, the sperm cells form a focused flow of sperm cells as they are flowed through the focusing channel. The focusing channel includes, in certain embodiments, a microchannel having a repetitively curved segment formed by a repeating series of identically-shaped curved sections, and some embodiments further characterize the identically-shaped curved sections as asymmetrically shaped.
Claims Coverage
The partial content identifies three independent claims that focus on geometric constraints for a microfluidic sperm focusing channel and a method of forming a focused flow. Across the independent claims, the main inventive features are the ratios a/Dh and 2r a^2 / Dh^3, together with repetitively curved microchannel segments and related refinements.
Geometric constraints on focusing channel ratios
A focusing channel spanning a length from an inlet to an outlet has a hydraulic diameter (Dh) such that a ratio of the cell diameter to the hydraulic diameter (a/Dh) is between about 0.03 and about 0.06 and a ratio of curvature (critical parameter “r”) to the hydraulic diameter (Dh), defined by 2r a^2 / Dh^3, is less than about 0.03.
Repetitively curved focusing channel segment
A focusing channel includes a microchannel having a repetitively curved segment comprising a repeating series of identically-shaped curved sections.
Curved section asymmetry and sperm type limitation
The identically-shaped curved sections are asymmetrically shaped and the sperm cells comprise bovine sperm.
Focused flow formation through constrained focusing channel
Providing a microfluidic chip comprising a focusing channel having a hydraulic diameter (Dh) and a ratio of curvature (critical parameter “r”) to the hydraulic diameter (Dh), defined by 2r a^2 / Dh^3, that is less than about 0.03, and flowing the sperm cells suspended in the fluid through the focusing channel to form a focused flow of sperm cells.
Claim coverage centers on microfluidic sperm focusing using a channel constrained by the geometric ratios a/Dh and 2r a^2 / Dh^3 to less than about 0.03. Dependent refinements further specify a repetitively curved microchannel segment with repeating identically-shaped curved sections, asymmetrically shaped curved sections in some embodiments, and bovine sperm as the sperm source. A method claim mirrors the chip geometry constraint and requires flowing sperm cells to form a focused flow.
Stated Advantages
Not explicitly described in patent.
Documented Applications
flow-cytometry-based semen sexing
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