Thermally cross-linkable photo-hydrolyzable inkjet printable polymers for microfluidic channels

Patent metadata

Field	Value
Publication number	US-2019210352-A1
Application number	US-201916357037-A
Country	US
Kind code	A1
Filing date	Mar 18, 2019
Priority date	Sep 12, 2012
Publication date	Jul 11, 2019
Grant date	—

Abstract

Thermally cross-linkable photo-hydrolyzable inkjet printable polymers are used to print microfluidic channels layer-by-layer on a substrate. In one embodiment, for each layer, an inkjet head deposits droplets of a mixture of hydrophobic polymer and cross-linking agent in a pattern lying outside a two-dimensional layout of the channels, and another inkjet head deposits droplets of a mixture of poly(tetrahydropyranyl methacrylate) PTHPMA (or another hydrophobic polymer which hydrolyzes to form a hydrophilic material), cross-linking agent, and a photoacid generator (PAG) in a pattern lying inside the two-dimensional layout of the channels. After all layers are printed, flood exposure of the entire substrate to UV radiation releases acid from the PAG which hydrolyzes PTHPMA to form hydrophilic poly(methacrylic acid) PMAA, thereby rendering the PTHPMA regions hydrophilic. The layers of these now-hydrophilic patterned regions together define the microfluidic channels. The cross-linking agent (e.g., triallyl isocyanurate TAIC) forms covalent cross-links between the two polymer phases.

First claim

What is claimed is:

1 . An apparatus for fabricating one or more microfluidic channels in a substrate body, comprising:
a print bed for receiving a substrate; a first mixture containing a first hydrophobic polymer and a first cross-linking agent; a second mixture containing a second hydrophobic polymer, a second cross-linking agent, and a photoacid generator, wherein the second hydrophobic polymer contains a hydrolyzable group and hydrolyzes to form a hydrophilic material; a first inkjet head configured to deliver a stream of droplets of the first mixture directed at a surface of the substrate; a second inkjet head configured to deliver a stream of droplets of the second mixture directed at the surface of the substrate; an x-y plane drive mechanism configured to produce relative movement between the first and second inkjet heads and the substrate in an x-y plane of the substrate, wherein the x-y plane drive mechanism, for each of a plurality of layers, moves the first inkjet head relative to the substrate so as to deposit droplets of the first mixture on the surface of the substrate in a first pattern lying outside a two-dimensional layout of the one or more microfluidic channels and moves the second inkjet head relative to the substrate so as to deposit droplets of the second mixture on the surface of the substrate in a second pattern lying inside the two-dimensional layout of the one or more microfluidic channels; wherein the first cross-linking agent and the second cross-linking agent each includes a multi-functional thermally cross-linkable monomer that copolymerizes with both the first hydrophobic polymer and the second hydrophobic polymer to form covalent cross-links between the first hydrophobic polymer and the second hydrophobic polymer after the droplets are deposited on the surface of the substrate and exposed to heat.

2 . The apparatus as recited in claim 1 , further comprising:
a heat source configured to heat the substrate having the plurality of layers deposited thereon to copolymerize each of the first cross-linking agent and the second cross-linking agent with both the first hydrophobic polymer and the second hydrophobic polymer to form covalent cross-links between the first hydrophobic polymer and the second hydrophobic polymer; a UV light source configured to expose the substrate having the plurality of layers deposited thereon and rendering the second hydrophobic polymer hydrophilic.

3 . The apparatus as recited in claim 1 , further comprising:
a z-axis drive mechanism configured to produce relative movement between the first and second inkjet heads and the substrate in a z direction of the substrate, wherein the z-axis drive mechanism, for each of the plurality of layers, after the droplets are deposited on the surface of the substrate moves the print bed by a predetermined distance in a direction away from the first and second inkjet heads, wherein the predetermined distance is the deposit depth of the droplets in that layer.

4 . The apparatus as recited in claim 1 , further comprising:
a computer system in which reside three-dimensional printing software and a microfluidic channel data file that comprises a three-dimensional representation of the one or more microfluidic channels; wherein the three-dimensional printing software is operative, for each of a plurality of layers, to develop the two-dimensional layout of the one or more microfluidic channels based on the microfluidic channel data file.

5 . The apparatus as recited in claim 1 , wherein the first and second inkjet heads are piezoelectric inkjet heads configured to deliver droplets having a volume of approximately 500-2000 femtoliters.

6 . The apparatus as recited in claim 1 , wherein the second hydrophobic polymer is selected from a group consisting of poly(tetrahydropyranyl methacrylate) (PTHPMA), poly(methyl methacrylate) (PMMA), and combinations thereof, and wherein the second cross-linking agent includes triallyl isocyanurate (TAIC).

7 . The apparatus as recited in claim 6 , wherein the first hydrophobic polymer is selected from a group consisting of poly(tetrahydropyranyl methacrylate) (PTHPMA), poly(methyl methacrylate) (PMMA), and combinations thereof, and wherein the first cross-linking agent includes triallyl isocyanurate (TAIC).

8 . The apparatus as recited in claim 6 , wherein the first hydrophobic polymer is selected from a group consisting of polystyrene, polyisobutylene, and combinations thereof, and wherein the first cross-linking agent includes triallyl isocyanurate (TAIC).

9 . A substrate body having one or more microfluidic channels fabricated therein made by a method of fabricating one or more microfluidic channels in a substrate body, the method comprising the steps of:
placing a substrate on a print bed; directing a stream of droplets of a first mixture from a first inkjet head at a surface of the substrate, wherein the first mixture contains a first hydrophobic polymer and a first cross-linking agent; directing a stream of droplets of a second mixture from a second inkjet head at the surface of the substrate, wherein the second mixture contains a second hydrophobic polymer, a second cross-linking agent, and a photoacid generator, and wherein the second hydrophobic polymer contains a hydrolyzable group and hydrolyzes to form a hydrophilic material; moving the first and second inkjet heads relative to the substrate in an x-y plane of the substrate, wherein the step of moving the first and second inkjet heads relative to the substrate in the x-y plane of the substrate, for each of a plurality of layers, includes the steps of:
moving the first inkjet head relative to the substrate so as to deposit droplets of the first mixture on the surface of the substrate in a first pattern based on a two-dimensional layout of the one or more microfluidic channels; and
moving the second inkjet head relative to the substrate so as to deposit droplets of the second mixture on the surface of the substrate in a second pattern based on the two-dimensional layout of the one or more microfluidic channels;
heating the substrate to copolymerize each of the first cross-linking agent and the second cross-linking agent with both the first hydrophobic polymer and the second hydrophobic polymer to form covalent cross-links between the first hydrophobic polymer and the second hydrophobic polymer; exposing the substrate having the plurality of layers deposited thereon to UV light to render the second hydrophobic polymer hydrophilic; wherein a concatenation of the second pattern of each respective one of the plurality of layers defines the one or more microfluidic channels.

10 . The substrate body as recited in claim 9 , wherein the covalent cross-links extend across an interface between the first mixture and the second mixture deposited on the substrate sufficiently to avoid phase separation and maintain the one or more microfluidic channels in a well-defined state.

11 . The substrate body as recited in claim 10 , wherein the second hydrophobic polymer is selected from a group consisting of poly(tetrahydropyranyl methacrylate) (PTHPMA), poly(methyl methacrylate) (PMMA), and combinations thereof, wherein the second cross-linking agent includes triallyl isocyanurate (TAIC), wherein the first hydrophobic polymer is selected from a group consisting of poly(tetrahydropyranyl methacrylate) (PTHPMA), poly(methyl methacrylate) (PMMA), and combinations thereof, and wherein the first cross-linking agent includes triallyl isocyanurate (TAIC).

12 . The substrate body as recited in claim 10 , wherein the second hydrophobic polymer is selected from a group consisting of poly(tetrahy

Assignees

• IBM

Inventors

• Boday Dylan J
• Kuczynski Joseph
• Meyer Iii Robert E

Classifications

• C09D11/106 Primary

  containing macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• B29C64/112

  using individual droplets, e.g. from jetting heads · CPC title

• B33Y50/02

  for controlling or regulating additive manufacturing processes · CPC title

• C09D4/06

  {Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond} in combination with a macromolecular compound other than an unsaturated polymer of groups C09D159/00 - C09D187/00 · CPC title

• B33Y30/00

  Apparatus for additive manufacturing; Details thereof or accessories therefor · CPC title