Microfabricated devices with coated or modified surface and method of making same

Abstract

A microfabricated device or component thereof, such as microfluidics or nanofluidics device having a uniform non-wetting or non-absorbing polymeric coating or surface modification formed on a surface thereof by ionisation or activation technology such as plasma processing, to produce a surface energy of less than 15 mNm −l . The treatment enhances the free-flowing properties of a liquid through the device during use.

1 . A method for enhancing the free-flowing properties of liquid through a microfluidic device with chambers and tunnels for the containment and flow of fluid, said method comprising using microfluidic device wherein at least a liquid contacting surface thereof has a surface energy value of less than 15 mNm −1  as a result of the presence of a uniform non-wetting or non-absorbing coating or surface modification formed thereon by plasma processing, wherein to produce the coating or surface modification the device or an element, component or sub-assembly thereof is exposed to a preliminary continuous plasma to pre-treat the liquid contacting surface so a monomer or monomers can attach to the surface, followed by a plasma to allow polymerization of the monomer(s) to proceed so the coating grows on the surface as a uniform coating. 
     
     
         2 . The method according to  claim 1 , wherein the plasma to allow the polymerization of the monomer(s) is a pulsed plasma. 
     
     
         3 . The method according to  claim 1 , wherein the said liquid contacting surface has deposited thereon a polymeric coating formed by exposing said surface to a pulsed plasma comprising a compound of formula (I) 
       
         
           
           
               
               
           
         
       
       where R 1 , R 2  and R 3  are independently selected from hydrogen, alkyl, haloalkyl or aryl optionally substituted by halo; and R 4  is a group —X—R 5  where R 5  is an alkyl or haloalkyl group and X is a bond; a group of formula —C(O)O—, a group of formula —C(O)O(CH 2 ) n Y— where n is an integer of from 1 to 10 and Y is a sulphonamide group; or a group —(O) p R 6 (O) q (CH 2 ) t — where R 6  is aryl optionally substituted by halo, p is 0 or 1, q is 0 or 1 and t is 0 or an integer of from 1 to 10, provided that where q is 1, t is other than 0,
 in a gaseous state for a sufficient period of time to allow a polymeric layer to form on the surface. 
 
     
     
         4 . The method according to  claim 1 , wherein the device or an element, component or sub-assembly thereof is placed in a plasma deposition chamber, a glow discharge is ignited within said chamber, and a voltage applied as a pulsed field. 
     
     
         5 . The method according to  claim 4 , wherein applied voltage is at a power of from 5 to 500 W. 
     
     
         6 . The method according to  claim 4 , wherein the voltage is pulsed in a sequence in which the ratio of the time on:time off is in the range of from 1:500 to 1:1500. 
     
     
         7 . The method according to  claim 6  wherein the voltage is pulsed in a sequence where power is on for 20-50 μs, and off for from 1000 μs to 30000 μs. 
     
     
         8 . The method according to  claim 4  wherein the voltage is applied as a pulsed field at for a period of from 30 seconds to 90 minutes. 
     
     
         9 . The method according to  claim 8  wherein the voltage is applied as a pulsed field for from 5 to 60 minutes. 
     
     
         10 . The method according to  claim 1 , wherein in a preliminary step, a continuous power plasma is applied to the microfluidic device or an element, component or sub-assembly thereof. 
     
     
         11 . The method according to  claim 10 , wherein the preliminary step is conducted in the presence of an inert gas. 
     
     
         12 . The method according to  claim 3 , wherein the compound of formula (I) in gaseous form is fed into the plasma at a rate of from 80-300 mg/minute, while the pulsed voltage is applied. 
     
     
         13 . The method according to  claim 3 , wherein the plasma is created with a voltage at an average power of from 0.001 to 500w/m 3 . 
     
     
         14 . The method according to  claim 13 , wherein the plasma is created with a voltage at an average power of from 0.001 to 100w/m 3 . 
     
     
         15 . The method according to  claim 14 , wherein the plasma is created with a voltage at an average power of from 0.005 to 0.5w/m 3 . 
     
     
         16 . The method according to  claim 3 , wherein the compound of formula (I) is a compound of formula (II)
   CH 2 ═CH—R 5   (II)
   where R 5  is as defined in  claim 5 , or a compound of formula (III)
   CH 2 ═CR 7 C(O)O(CH 2 ) n R 5   (III)
 
   
       where n and R 5  as defined in  claim 5  and R 7  is hydrogen, C 1-10  alkyl, or C 1-10 haloalkyl. 
     
     
         17 . The method according to  claim 16 , wherein the compound of formula (I) is a compound of formula (III). 
     
     
         18 . The method according to  claim 17 , wherein the compound of formula (III) is a compound of formula (IV) 
       
         
           
           
               
               
           
         
       
       where R 7  is as defined in  claim 16 , and x is an integer of from 1 to 9. 
     
     
         19 . The method according to  claim 18 , wherein the compound of formula (IV) is 1H, 1H, 2H, 2H-heptadecafluorodecyl acrylate. 
     
     
         20 . A method for enhancing the free-flowing properties of liquid through a nanofluidic device with chambers and tunnels for the containment and flow of fluid, said method comprising using nanofluidic device wherein at least a liquid contacting surface thereof has a surface energy value of less than 15 mNm −1  as a result of the presence of a uniform non-wetting or non-absorbing coating or surface modification formed thereon by plasma processing, wherein to produce the coating or surface modification the device or an element, component or sub-assembly thereof is exposed to a preliminary continuous plasma to pre-treat the liquid contacting surface so a monomer or monomers can attach to the surface, followed by a plasma to allow polymerization of the monomer(s) to proceed so the coating grows on the surface as a uniform coating. 
     
     
         21 . The method according to  claim 20 , wherein the plasma to allow the polymerization of the monomer(s) is a pulsed plasma. 
     
     
         22 . The method according to  claim 20 , wherein the said liquid contacting surface has deposited thereon a polymeric coating formed by exposing said surface to a pulsed plasma comprising a compound of formula (I) 
       
         
           
           
               
               
           
         
         where R 1 , R 2  and R 3  are independently selected from hydrogen, alkyl, haloalkyl or aryl optionally substituted by halo; and R 4  is a group —X—R 5  where R 5  is an alkyl or haloalkyl group and X is a bond; a group of formula —C(O)O—, a group of formula —C(O)O(CH 2 ) n Y— where n is an integer of from 1 to 10 and Y is a sulphonamide group; or a group —(O) p R 6 (O) q (CH 2 ) t — where R 6  is aryl optionally substituted by halo, p is 0 or 1, q is 0 or 1 and t is 0 or an integer of from 1 to 10, provided that where q is 1, t is other than 0, 
         in a gaseous state for a sufficient period of time to allow a polymeric layer to form on the surface. 
       
     
     
         23 . The method according to  claim 20 , wherein the device or an element, component or sub-assembly thereof is placed in a plasma deposition chamber, a glow discharge is ignited within said chamber, and a voltage applied as a pulsed field. 
     
     
         24 . The method according to  claim 23 , wherein applied voltage is at a power of from 5 to 500 W. 
     
     
         25 . The method according to  claim 23 , wherein the voltage is pulsed in a sequence in which the ratio of the time on:time off is in the range of from 1:500 to 1:1500. 
     
     
         26 . The method according to  claim 25 , wherein the voltage is pulsed in a sequence where power is on for 20-50 μs, and off for from 1000 μs to 30000 μs. 
     
     
         27 . The method according to  claim 23 , wherein the voltage is applied as a pulsed field at for a period of from 30 seconds to 90 minutes. 
     
     
         28 . The method according to  claim 27 , wherein the voltage is applied as a pulsed field for from 5 to 60 minutes. 
     
     
         29 . The method according to  claim 20 , wherein in a preliminary step, a continuous power plasma is applied to the nanofluidic device or an element, component or sub-assembly thereof. 
     
     
         30 . The method according to  claim 29 , wherein the preliminary step is conducted in the presence of an inert gas. 
     
     
         31 . The method according to  claim 22 , wherein the compound of formula (I) in gaseous form is fed into the plasma at a rate of from 80-300 mg/minute, while the pulsed voltage is applied. 
     
     
         32 . The method according to  claim 22 , wherein the plasma is created with a voltage at an average power of from 0.001 to 500w/m 3 . 
     
     
         33 . The method according to  claim 32 , wherein the plasma is created with a voltage at an average power of from 0.001 to 100w/m 3 . 
     
     
         34 . The method according to  claim 33 , wherein the plasma is created with a voltage at an average power of from 0.005 to 0.5w/m 3 . 
     
     
         35 . The method according to  claim 22 , wherein the compound of formula (I) is a compound of formula (II)
   CH 2 ═CH—R 5   (II)
   
       where R 5  is as defined in  claim 5 , or a compound of formula (III)
   CH 2 ═CR 7 C(O)O(CH 2 ) n R 5   (III)
 
 where n and R 5  as defined in  claim 5  and R 7  is hydrogen, C 1-10  alkyl, or C 1-10 haloalkyl. 
 
     
     
         36 . The method according to  claim 35 , wherein the compound of formula (I) is a compound of formula (III). 
     
     
         37 . The method according to  claim 36 , wherein the compound of formula (III) is a compound of formula (IV) 
       
         
           
           
               
               
           
         
         where R 7  is as defined in  claim 35 , and x is an integer of from 1 to 9. 
       
     
     
         38 . The method according to  claim 37 , wherein the compound of formula (IV) is 1H, 1H, 2H, 2H-heptadecafluorodecyl acrylate. 
     
     
         39 . A microfluidic device with a uniform coating on an element, component or sub-assembly thereof made by the method of  claim 1 . 
     
     
         40 . A nanofluidic device with a uniform coating on an element, component or sub-assembly thereof made by the method of  claim 20 .