Microfluidic structure

Abstract

A microfluidic structure comprising a thermoplastic portion defining a microfluidic recess, a bonding layer on the thermoplastic portion and a siloxane elastomer portion covalently bonded to the bonding layer to seal the microfluidic recess. The microfluidic recess can therefore be formed simply, quickly and cheaply using known injection molding techniques, which are not hampered by the need for a curing step. However, the positive qualities associated with elastomers can be brought to the structure by using this to seal the microchannels. The bonding layer can be formed by silica deposited on the thermoplastic portion using techniques known in the field of optics.

1 . A microfluidic structure comprising a thermoplastic portion defining a microfluidic recess, a bonding layer on the thermoplastic portion and a siloxane elastomer portion covalently bonded to the bonding layer to seal the microfluidic recess. 
     
     
         2 . A microfluidic structure as claimed in  claim 1  wherein the bonding layer is formed from silica. 
     
     
         3 . A microfluidic structure as claimed in  claim 2  wherein the silica and siloxane elastomer are oxidised and form a covalent bond. 
     
     
         4 . A microfluidic structure as claimed in  claim 1 ,  2  or  3  wherein the siloxane elastomer portion is additionally bonded to another material. 
     
     
         5 . A microfluidic structure as claimed in  claim 4  wherein the siloxane elastomer portion is covalently bonded to two thermoplastic portions each having a microfluidic recess. 
     
     
         6 . A microfluidic structure as claimed in  claim 5  wherein the siloxane elastomer is (poly)dimethylsiloxane (PDMS). 
     
     
         7 . A microfluidic structure comprising a thermoplastic portion defining a microfluidic recess, a layer of silica on the thermoplastic portion and a PDMS portion covalently bonded to the silica layer such that it seals the microfluidic recess. 
     
     
         8 . A method of manufacturing a microfluidic structure comprising the steps of
 providing a thermoplastic portion having a microfluidic recess;   depositing a layer of silica on the thermoplastic portion;   oxidising the silica layer; and   bringing the oxidised layer of silica into contact with an oxidised portion of PDMS to create an covalent bond.   
     
     
         9 . A method as claimed in  claim 8 , wherein the silica is deposited using electron beam evaporation. 
     
     
         10 . A method as claimed in  claim 8 , wherein the silica is deposited by liquid phase deposition. 
     
     
         11 . A method as claimed in  claim 8 , wherein the silica is deposited by chemical vapour deposition. 
     
     
         12 . A method as claimed in any of  claims 8  to  11 , wherein the bonding step does not involve external pressure. 
     
     
         13 . A method as claimed in any of  claims 8  to  12 , wherein the thermoplastic portion is injection moulded. 
     
     
         14 . A thermoplastic portion having a microfluidic recess in its upper surface and a layer of silica deposited on the upper surface. 
     
     
         15 . A method of preparing a thermoplastic portion, comprising forming a microfluidic recess in its upper surface and depositing a layer of silica on the upper surface. 
     
     
         16 . A method of manufacturing a microfluidic structure comprising the steps of forming a substrate having a microfluidic recess and depositing a layer of silica on the substrate by liquid phase deposition. 
     
     
         17 . Use of the microfluidic structure as claimed in any of  claims 1  to  7  for fluorescence detection. 
     
     
         18 . Use as claimed in  claim 17  wherein the fluorescence is provided by labeled cells or concatemeric DNA molecules. 
     
     
         19 . Use of the microfluidic structure as claimed in any of  claims 1  to  7  for cell culture. 
     
     
         20 . Use of the microfluidic structure as claimed in any of  claims 1  to  7  for construction of valves and pumps.