Fabrication method of microfluidic circuit, and microfluidic circuit fabricated by method thereof

• US 8,377,391 B2
• Filed: 06/13/2011
• Issued: 02/19/2013
• Est. Priority Date: 05/16/2006
• Status: Active Grant

• Current Assignee: Horiba Limited
• Original Assignee: ROHM Co., Ltd.
• Inventors: Momose, Shun
• Primary Examiner(s): KWAK, DEAN P
• Application Number:
  US13/158,957
• Publication Number:
  US 20110244559A1
• Time in Patent Office: 617 Days
• Field of Search: 422500-504, 436/180
• US Class Current: 422/503
• CPC Class Codes: B01L 3/5027 by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29C 65/14 using wave energy , i.e. electromagnetic radiation, or particle radiation using mechanical waves B29C65/06; using ultrasonic waves B29C65/08; pressing means transparent to electromagnetic radiation B29C66/81267
• CPC Class Codes: B29C 65/1406 Ultraviolet [UV] radiation
• CPC Class Codes: B29C 65/1435 at least passing through one of the parts to be joined, i.e. transmission welding
• CPC Class Codes: B29C 65/149 being a part of the joined article
• CPC Class Codes: B29C 65/1493 in the form of a cavity
• CPC Class Codes: B29C 65/1496 making use of masks B29C65/1696 takes precedence
• CPC Class Codes: B29C 65/1616 Near infrared radiation [NIR], e.g. by YAG lasers
• CPC Class Codes: B29C 65/1635 at least passing through one of the parts to be joined, i.e. laser transmission welding
• CPC Class Codes: B29C 65/1654 scanning at least one of the parts to be joined
• CPC Class Codes: B29C 65/169 being a part of the joined article
• CPC Class Codes: B29C 65/1693 in the form of a cavity
• CPC Class Codes: B29C 65/1696 making use of masks
• CPC Class Codes: B29C 66/112 Single lapped joints
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/114 Single butt joints
• CPC Class Codes: B29C 66/5346 said single elements being substantially flat
• CPC Class Codes: B29C 66/53461 joining substantially flat covers and/or substantially flat bottoms to open ends of container bodies
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/73161 : Roughness or rugosity
• CPC Class Codes: B29C 66/73341 : at least one of the parts to be joined being glossy or reflective
• CPC Class Codes: B29C 66/73343 : at least one of the parts to be joined being matt or refractive
• CPC Class Codes: B29C 66/73365 : at least one of the parts to be joined being transparent or translucent to visible light
• CPC Class Codes: B29C 66/73521 : of different thickness, i.e. the thickness of one of the parts to be joined being different from the thickness of the other part
• CPC Class Codes: B29C 66/73921 : characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/836 : Moving relative to and tangentially to the parts to be joined, e.g. transversely to the displacement of the parts to be joined, e.g. using a X-Y table B29C66/65 takes precedence
• CPC Class Codes: B29K 2023/12 : PP, i.e. polypropylene
• CPC Class Codes: B29K 2023/38 : Polymers of cycloalkenes, e.g. norbornene or cyclopentene
• CPC Class Codes: B29K 2025/00 : Use of polymers of vinyl-aromatic compounds or derivatives thereof as moulding material
• CPC Class Codes: B29K 2025/06 : PS, i.e. polystyrene
• CPC Class Codes: B29K 2027/06 : PVC, i.e. polyvinylchloride
• CPC Class Codes: B29K 2033/12 : Polymers of methacrylic acid esters, e.g. PMMA, i.e. polymethylmethacrylate
• CPC Class Codes: B29K 2067/00 : Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2067/003 : PET, i.e. poylethylene terephthalate
• CPC Class Codes: B29K 2069/00 : Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2995/0027 : for light outside the visible spectrum
• CPC Class Codes: B29K 2995/0072 : Roughness, e.g. anti-slip
• CPC Class Codes: B29L 2031/756 : Microarticles, nanoarticles
• CPC Class Codes: B81B 2201/058 : Microfluidics not provided for in B81B2201/051 - B81B2201/054
• CPC Class Codes: B81C 3/001 : Bonding of two components
• CPC Class Codes: Y10T 29/49826 : Assembling or joining
• CPC Class Codes: Y10T 436/2575 : Volumetric liquid transfer

Abstract

A fabrication method of a microfluidic circuit is provided, dispensable of mask registration, absent of deviation in mask positioning, and inexpensive in fabrication cost. The fabrication method of a microfluidic circuit has a light transmissive substrate stacked on a light absorptive substrate, and the light transmissive substrate welded with the light absorptive substrate for bonding by directing light through the light transmissive substrate. The microfluidic circuit includes a microchannel at the bottom face of the light transmissive substrate and/or at the top face of the light absorptive substrate. The method includes the step of forming, at the light transmissive substrate, a light attenuation region attenuating transmittance of light towards the microchannel when light is directed through the light transmissive substrate.

Claims

1. A fabrication method of a microfluidic circuit having a light transmissive substrate that is composed of thermoplastic resin and that is stacked on a light absorptive substrate, said microfluidic circuit including a microchannel at a bottom face of said light transmissive substrate and/or at a top face of said light absorptive substrate, said method comprising:

forming, at said light transmissive substrate, a light attenuation region attenuating an amount of light to not more than 80%, wherein said light attenuation region contains a light blocking material composed of carbon black,

after forming the light attenuation region, welding the light transmissive substrate to the light absorptive substrate by directing light through the light transmissive substrate, wherein the amount of light transmitted toward said microchannel is attenuated, by said light attenuation region, to not more than 80% of an amount of light directed to said light transmissive substrate,

wherein said light transmissive substrate has a thickness d and a refraction index n, and includes a microchannel of a width w at a bottom face, and a value of (d/w) tan [90−

θ

−

sin<sup>−

1</sup>{(sin(90−

θ

))/n}] is at least 0.1, where θ

is an incident angle of directed light transmitted to said microchannel.

2. The fabrication method of a microfluidic circuit according to claim 1, wherein said light attenuation region at said light transmissive substrate includes a surface having an arithmetical mean roughness Ra of 1 μ

m to 50 μ

m.

3. The fabrication method of a microfluidic circuit according to claim 1, wherein said light attenuation region at said light transmissive substrate includes a cavity having a face such that light directed substantially perpendicularly with respect to a top face of the light transmissive substrate does not enter perpendicularly to the face of the cavity.

4. A microfluidic circuit fabricated by the method of claim 1.