A versatile and flexible low-temperature full-wafer bonding process of monolithic 3D microfluidic structures in SU-8

We present a versatile fabrication process for the precise fabrication of embedded three-dimensional microfluidic structures in SU-8 photoresist. The full-wafer bond process based on a polyester (PET) handling layer enhances the previous low-temperature bonding technology. We achieved an extremely high bond strength of 45 MPa while requiring only small anchoring structures. Small channel structures with an aspect ratio >2 as well as wide membranes with an aspect ratio 80%) and enables the integration of microelectronics. The flexibility of the fabrication process is presented in two contrary applications. A completely freestanding and transparent SU-8 foil with a thickness of 225 µm featuring embedded 3D microchannels was fabricated. Also, high quality ink-jet dispensers were successfully fabricated whereas the dispenser quality mainly depends on the channel quality.

[1]  Jan C T Eijkel,et al.  Nanochannels in SU-8 with floor and ceiling metal electrodes and integrated microchannels. , 2008, Lab on a chip.

[2]  G M Whitesides,et al.  Fabrication of topologically complex three-dimensional microfluidic systems in PDMS by rapid prototyping. , 2000, Analytical chemistry.

[3]  Yong Huang,et al.  Flow-through micro-electroporation chip for high efficiency single-cell genetic manipulation , 2003 .

[4]  Jane M. Shaw,et al.  Micromachining applications of a high resolution ultrathick photoresist , 1995 .

[5]  Bernhard H Weigl,et al.  Microfluidic technologies in clinical diagnostics. , 2002, Clinica chimica acta; international journal of clinical chemistry.

[6]  R. Zengerle,et al.  Rapid prototyping of microfluidic chips in COC , 2007 .

[7]  David Paul Steenson,et al.  Microfabrication of channels using an embedded mask in negative resist , 2001 .

[8]  P. Renaud,et al.  Polyimide and SU-8 microfluidic devices manufactured by heat-depolymerizable sacrificial material technique. , 2004, Lab on a chip.

[9]  D. Jenkins,et al.  Comparative assessment of different sacrificial materials for releasing SU-8 structures , 2005 .

[10]  Roland Zengerle,et al.  Discrete Chemical Release From a microfluidic Chip , 2006 .

[11]  Roland Zengerle,et al.  Rapid prototyping of microfluidic chips in COC , 2007 .

[12]  Hsiharng Yang,et al.  A low-temperature wafer bonding technique using patternable materials , 2002 .

[13]  Stéphane Colin,et al.  A novel fabrication method of flexible and monolithic 3D microfluidic structures using lamination of SU-8 films , 2005 .

[14]  Robert C. White,et al.  Fabrication of a fluid encapsulated dermal patch using multilayered SU-8 , 2004 .

[15]  Wei-Keng Lin,et al.  A novel fabrication method of embedded micro-channels by using SU-8 thick-film photoresists , 2003 .

[16]  Robert M. Young,et al.  Fabrication of micronozzles using low-temperature wafer-level bonding with SU-8 , 2003 .

[17]  R. Ghodssi,et al.  Microfluidic systems with on-line UV detection fabricated in photodefinable epoxy , 2001 .

[18]  Rebecca S. Shawgo,et al.  Biocompatibility and biofouling of MEMS drug delivery devices. , 2003, Biomaterials.

[19]  Masayoshi Esashi,et al.  Fabrication and high-speed characterization of SU-8 shrouded two-dimensional microimpellers , 2007 .

[20]  Roland Zengerle,et al.  Multi-layer SU-8 lift-off technology for microfluidic devices , 2005 .

[21]  S. Quake,et al.  Microfluidic Large-Scale Integration , 2002, Science.

[22]  Francis E. H. Tay,et al.  A novel micro-machining method for the fabrication of thick-film SU-8 embedded micro-channels , 2001 .

[23]  Daniel Bertrand,et al.  Buried microchannels in photopolymer for delivering of solutions to neurons in a network , 1998 .

[24]  G. Liu,et al.  Fabrication of microchannels in negative resist , 2003 .

[25]  N. Fabre,et al.  Surface micromachining technology with two SU-8 structural layers and sol–gel, SU-8 or SiO2/sol–gel sacrificial layers , 2007 .

[26]  Mark G. Allen,et al.  Uncrosslinked SU-8 as a sacrificial material , 2005 .

[27]  S. Quake,et al.  Monolithic microfabricated valves and pumps by multilayer soft lithography. , 2000, Science.

[28]  P. Svaseka,et al.  Fabrication of miniaturized fluidic devices using SU-8 based lithography and low temperature wafer bonding , 2004 .

[29]  M. Despont,et al.  SU-8: a low-cost negative resist for MEMS , 1997 .

[30]  Steve Arscott,et al.  Integrated microfluidics based on multi-layered SU-8 for mass spectrometry analysis , 2004 .

[31]  Roland Zengerle,et al.  Microfluidic platforms for lab-on-a-chip applications. , 2007, Lab on a chip.

[32]  M. Tijero,et al.  Novel three-dimensional embedded SU-8 microchannels fabricated using a low temperature full wafer adhesive bonding , 2004 .

[33]  B. Roberds,et al.  Low temperature Si3N4 direct bonding , 1993 .

[34]  Anders Kristensen,et al.  PMMA to SU-8 bonding for polymer based lab-on-a-chip systems with integrated optics , 2004 .

[35]  F J Blanco,et al.  Fabrication of SU-8 multilayer microstructures based on successive CMOS compatible adhesive bonding and releasing steps. , 2005, Lab on a chip.

[36]  S. Franssila,et al.  Free-standing SU-8 microfluidic chips by adhesive bonding and release etching , 2005 .

[37]  Pratul K. Ajmera,et al.  Use of a photoresist sacrificial layer with SU-8 electroplating mould in MEMS fabrication , 2003 .