Method for improving the bonding properties of microstructured substrates, and devices prepared with this method

Abstract

A method for treating the surface of a polymeric substrate, including the following steps: providing a first polymeric substrate; contracting at least one part of one face of the first substrate with some liquid solvent system, the liquid solvent system containing at least a first volatile compound and at least a second compound having a low molecular weight and able to swell and/or soften the polymeric material forming the face; letting at least the volatile compound to evaporate from the face of the first substrate and; contacting the so-treated face of first substrate with a third material.

1 . A method for treating the surface of a polymeric substrate, comprising the following steps:
 a/ providing a first polymeric substrate,   b/ contacting at least one part of one face of said first substrate with some liquid solvent system, said liquid solvent system containing at least a first volatile compound and at least a second compound having a low molecular weight and able to swell and/or soften the polymeric material forming said face,   c/ letting at least said volatile compound to evaporate from said face of said first substrate and   d/ contacting the so-treated face of first substrate with a third material.   
     
     
         2 . The method according to  claim 1  wherein the first substrate is formed from a polymeric material selected from the group consisting of thermoplastic polymers, crosslinked or non-crosslinked elastomers, and chemically crosslinked resins. 
     
     
         3 . The method according to  claim 1  wherein the first substrate is formed from a polymer selected from cyclic olefin polymers, cyclic olefin copolymers, polymers containing norbomene moieties, polymethylmethacrylate, acrylic polymers or copolymers, polystyrene, substituted polystyrene, polycarbonate, polyimide, silicone elastomers, fluoropolymers, polyolefins, epoxies, polyurethanes, polyesters, polyethylene terephtalate, polypersulfone, and polyether ketones. 
     
     
         4 . The method according to  claim 1  wherein, said first substrate is rigid. 
     
     
         5 . The method according to  claim 1  wherein said first substrate is flexible. 
     
     
         6 . The method according to  claim 1  wherein said first substrate is a sheetlike substrate. 
     
     
         7 . The method according to  claim 1  wherein the proportion of said first compound in said liquid solvent system is higher than 50%. 
     
     
         8 . The method according to  claim 1  wherein the proportion of said second compound in said liquid solvent system is comprised between 1% and 45%. 
     
     
         9 . The method according to  claim 1  wherein said first compound is a poor solvent of the polymeric material forming the first substrate. 
     
     
         10 . The method according to  claim 1  wherein said first compound is more volatile than said second compound. 
     
     
         11 . The method according to  claim 1  wherein said first and second compound are miscible. 
     
     
         12 . The method according to  claim 1  wherein the liquid solvent system is a mixture of toluene/acetone for a first substrate based on polydimethylsiloxane (PDMS), a mixture of chloroforme/ethanol for a first substrate based on polymethylmethacrylate (PMMA), a mixture of chloroforme/methanol for a first substrate based on polycarbonate; a mixture of phenol/ethanol for a first substrate based on PolyEthylene Terephtalate (PET), a mixture of dichloromethane/ethyl acetate or of hexadecane/isopropanol for a first substrate based on cyclic olefin copolymers (COC) and a mixture of ethyl acetate/acetone for a first substrate based on Polystyrene. 
     
     
         13 . The method according to  claim 1  wherein the third material is a template bearing a negative of microstructures to be transferred into said first substrate. 
     
     
         14 . The method according to  claim 13  wherein the transfer is performed at a temperature below the glass transition of said first substrate. 
     
     
         15 . The method according to  claim 13  wherein the transfer is performed at a temperature above the glass transition of the first substrate, typically no more than 30° C. above said glass transition temperature. 
     
     
         16 . The method according to  claim 1  wherein the third material is selected from the group consisting of polymers, monomers, biological macromolecules such as nucleic acids, nucleic acids analogs, proteins, peptides, polysaccharides, proteoglycans, organic, inorganic or composite organic/inorganic microparticles or nanoparticles. 
     
     
         17 . The method according to  claim 1  wherein the third material is a second substrate to be bonded to the first substrate. 
     
     
         18 . The method according to  claim 17  wherein the second substrate is a sheetlike substrate. 
     
     
         19 . The method according to  claim 18  wherein either said first substrate or said second substrate or both, bear on their surfaces to be bonded, microstructures defining an integrated microchannel network, or an integrated microreservoir. 
     
     
         20 . Flexible microsystem comprising at least one embedded microchannels network, wherein said network involves at least one microchannel with a length larger than 10 cm, and does not involve in-plane turns with a radius of gyration smaller than 1/10th of the microchannel length. 
     
     
         21 . The microsystem of  claim 20  obtained according to the method of  claim 1 . 
     
     
         22 . The microsystem according to  claim 20  wherein said microchannel has a depth smaller than 60 μm. 
     
     
         23 . The microsystem according to  claim 20  wherein said microchannel has a length of at least 8 cm. 
     
     
         24 . A microfluidic device comprising a flexible microsystem according to  claim 20 , and at least two functional elements wherein said functional elements are independently aligned with regards to two different parts of said microchannel network, and wherein said parts can be moved with regards to each other without altering the integrity of said microchannels network or microchannels array. 
     
     
         25 . The microfluidic device of  claim 24  wherein the two functional elements collectively comprise a detector and a fluidic connection, or a detector and a fluidic sampler.