WO 01/07159
`
`PCT/IB00/01137
`
`2 8
`
`- the microfluidic device comprises a substrate into which the one or more channels are formed: and
`
`- the substrate comprises, consists essentially of or consists of silicon, glass, quartz andlor plastic.
`
`A process is also provided according to the invention for carrying out chemical or biochemical reactions
`
`involving thermal cycling, in which at least one channel is fed continuously with a solution, and the solution is provided
`
`with at least two predetermined temperatures such that the solution is adjusted to the desired temperatures when it
`
`runs through the channel once, and in which the channel is transferred from one to another of the temperatures over
`
`time while the solution runs through the channel.
`
`in one embodiment, the process has at least one of the following properties:
`
`- the reaction comprises DNA or DNA fragments:
`
`- the reaction implements a synthesis of DNA or of a fragment of DNA: and
`
`- the reaction comprises a polymerase chain reaction.
`
`A product is also provided according to the invention, which has undergone a chemical or biochemical
`
`reaction which is carried out according to a process in accordance with the invention.
`
`We will describe, with reference to Figures 13 to 17, the principles of five embodiments of the device of the
`
`invention, applied herein to the implementation of a PCR protocol with thermal cycling.
`
`In the first embodiment illustrated in Figure 13, the device 101 comprises a thermal cycling unit 102
`
`comprising a substrate 103. The substrate will be described below in greater detail with reference to Figures 18 to
`
`20. The substrate 103 has a channel 108 which is in fluid communication, via its upstream end, with an upstream
`
`feed pipe 116 and, via its downstream end, with a downstream outlet pipe 1 18.
`
`The device 101 comprises components 105 for continuously running through the channel 108 a solution
`
`which is supplied via the pipe 116 and which leaves via the pipe 118, the solution thus running through the channel
`
`108 a single time throughout its length during the entire protocol. The solution contains the reagents required for
`
`carrying out the PCR.
`
`The unit 102 comprises components for heating or cooling the substrate 103 at will, these components
`
`being conventional and known per se. In some embodiments, the heating components comprise reservoirs containing
`
`solutions at the desired temperatures which are in fluid communication with channels in a metal bar which contacts
`
`the microfluidic substrate as illustrated in Figures 1 and 2.
`
`In the following and for simplicity, these components will
`
`be termed heating components, it being understood that they are used for heating and for cooling, and thus make it
`
`possible to raise or to lower the temperature of the substrate and of the channel. The heating components are
`
`constructed so as to heat or cool the substrate 103 in its entirety, such that whatever the temperature that they
`
`confer on the channel 108 at a given instant, all the segments of the channel 108 are at the same temperature.
`
`The unit 102 comprises components for controlling the heating components, so that they provide the
`
`channel 108 with different successive temperatures over time. These temperatures herein number three, and are
`
`those which are known and which are used during the PCR. Thus, the channel 108 is first placed at a temperature
`
`T1, then cooled to a temperature T2, then reheated to an intermediate temperature T3. This temporal series forms a
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`