Microfluidic systems including three-dimensionally arrayed channel networks

A microfluidic network comprising:

• an elastomeric structure including therein at least a one fluid flow path, with the flow path comprising a series of interconnected channels within the structure, the series of interconnected channels including at least one first channel disposed within a first level of the structure, at least one second channel disposed within a second level of the structure, and at least one connecting channel fluidically interconnecting the first channel and the second channel,
• where at least one channel within the structure has cross-sectional dimension not exceeding about 500 μm,
• where the structure includes at least one channel disposed within the first level of the structure that is non-parallel to at least one channel disposed within the second level of the structure;
• wherein the structure is comprised of at least two discrete layers of polymeric material, each layer including at least one channel therein, the layers being stacked one upon each other;
• wherein a first discrete layer of the structure includes a surface defining the first level of the structure and having the at least one first channel disposed therein and further includes at least one channel traversing a thickness of the layer and forming the at least one connecting channel;
• and
• wherein a second discrete layer of the structure includes a surface defining the second level of the structure and having the at least one second channel disposed therein.

A microfluidic network comprising:

• an elastomeric structure including therein at least a one fluid flow path, with the flow path comprising a series of interconnected channels within the structure, the series of interconnected channels including at least one first channel disposed within a first level of the structure, at least one second channel disposed within a second level of the structure, and at least one connecting channel fluidically interconnecting the first channel and the second channel,
• where at least one channel within the structure has cross-sectional dimension not exceeding about 500 μm, and
• where the structure includes at least one channel disposed within the first level of the structure that is non-parallel to at least one channel disposed within the second level of the structure;
• wherein the structure is comprised of at least one discrete layer of polymeric material;
• wherein the at least one discrete layer comprises a polymeric membrane including a first surface defining the first level of the structure and having the at least one first channel disposed therein, a second surface defining the second level of the structure and having the at least one second channel disposed therein, and a polymeric region intermediate the first surface and the second surface, the region including the at least one connecting channel therethrough fluidically interconnecting the first channel disposed in the first surface and the second channel disposed in the second surface of the membrane.

A polymeric membrane comprising:

• a first surface including at least one channel disposed therein;
• a second surface including at least one channel disposed therein;
• and
• a polymeric region intermediate the first surface and the second surface, the region including at least one connecting channel therethrough fluidically interconnecting the channel disposed in the first surface and the channel disposed in the second surface of the membrane, where
• at least one channel has a cross-sectional dimension not exceeding about 500 μm.

A method for forming a microfluidic network structure comprising:

• providing at least one mold substrate;
• forming at least one topological feature on a surface of the mold substrate to form a first mold master, where at least one of said at least one topological feature is a two-level topological feature characterized by a first portion having a first depth or height with respect to a region of the surface adjacent to the feature and a second portion, integrally connected to the first portion, having a second depth or height with respect to the region of the surface adjacent to the feature, which is greater than the first depth or height;
• contacting the surface with a first hardenable liquid;
• hardening the liquid thereby creating a first molded replica of the surface;
• removing the first molded replica from the first mold master;
• and assembling the first molded replica into a structure comprising a microfluidic network having at least a one fluid flow path comprising a series of interconnected channels within the structure, the series of interconnected channels including at least one first channel disposed within a first level of the structure, at least one second channel disposed within a second level of the structure, and at least one connecting channel fluidically interconnecting the first channel and the second channel, where at least one of which channels has a cross-sectional dimension not exceeding about 500 μm and where the structure includes at least one channel disposed within the first level of the structure that is non-parallel to at least one channel disposed within the second level of the structure.

A method for forming a molded structure comprising:

• providing at least one mold substrate;
• forming at least one two-level topological feature having at least one cross-sectional dimension not exceeding about 500 μm on a surface of the substrate to form a mold master, which two-level topological feature is characterized by a first portion having a first depth or height with respect to a region of the surface adjacent to the feature and a second portion, integrally connected to the first portion, having a second depth or height with respect to the region of the surface adjacent to the feature, which is greater than the first depth or height;
• contacting the surface with a hardenable liquid;
• hardening the liquid thereby creating a molded replica of the surface;
• and
• removing the molded replica from the mold master.

A method for forming topological features on a surface of a material comprising:

• exposing portions of surface of a first layer of photoresist to radiation in a first pattern;
• coating the surface of the first layer of photoresist with a second layer of photoresist;
• exposing portions of a surface of the second layer of photoresist to radiation in a second pattern different from the first pattern;
• and
• developing the first and second photoresist layers with a developing agent to yield a positive relief pattern in photoresist, the positive relief pattern including at least one two-level topological feature having at least one cross-sectional dimension not exceeding about 500 μm, which two-level topological feature is characterized by a first portion having a first height with respect to the surface of the material and a second portion, integrally connected to the first portion, having a second height with respect to the surface of the material.

A method for forming a molded structure comprising:

• providing a first mold master having a surface formed of an elastomeric material and including at least one topological feature with at least one cross-sectional dimension not exceeding about 500 μm thereon;
• providing a second mold master having a surface including at least one topological feature with at least one cross-sectional dimension not exceeding about 500 μm thereon;
• placing a hardenable liquid in contact with the surface of at least one of the first and second mold master;
• bringing the surface of the first mold master into at least partial contact with the surface of the second mold master;
• hardening the liquid thereby creating a molded replica of the surface of the first mold master and the surface of the second mold master;
• and
• removing the molded replica from at least one of the mold masters.

A method for forming a molded structure comprising:

• providing a first mold master having a surface including at least a first topological feature with at least one cross-sectional dimension not exceeding about 500 μm thereon and at least a second topological feature comprising a first alignment element;
• providing a second mold master having a surface including at least a first topological feature with at least one cross-sectional dimension not exceeding about 500 μm thereon and at least a second topological feature comprising a second alignment element having a shape that is matable to the shape of the first alignment element;
• placing a hardenable liquid in contact with the surface of at least one of the first and second mold master;
• bringing the surface of the first mold master into at least partial contact with the surface of the second mold master;
• aligning the first topological features of the first and second mold masters with respect to each other by adjusting a position of the first mold master with respect to a position of the second mold master until the first alignment element matingly engages the second alignment element;
• hardening the liquid thereby creating a molded replica of the surface of the first mold master and the surface of the second mold master;
• and
• removing the molded replica from at least one of the mold masters.

A method for aligning and sealing together surfaces comprising:

• disposing two surfaces comprised of different materials, at least one of which surfaces is oxidized, adjacent to each other such that they are separated from each other by a continuous layer of a liquid that is essentially non-reactive with the surfaces;
• aligning the surfaces with respect to each other;
• and
• removing the liquid from between the surfaces, thereby sealing the surfaces together via a chemical reaction between the surfaces.

A method for molding an article comprising:

• providing a first mold master having a surface with a first set of surface properties;
• providing a second mold master having a surface with a second set of surface properties, wherein the surface of at least the first mold master is formed of an elastomeric material, and wherein at least one of the first and second mold master has a surface including at least one topological feature with at least one cross-sectional dimension not exceeding about 500 μm thereon;
• placing a hardenable liquid in contact with the surface of at least one of the first and second mold master;
• bringing the surface of the first mold master into at least partial contact with the surface of the second mold master;
• hardening the liquid thereby creating a molded replica of the surface of the first mold master and the surface of the second mold master;
• separating the masters from each other;
• and
• removing the molded replica from the surface of the first mold master while leaving the molded replica in contact with and supported by the surface of the second mold master.