Fluidic devices and methods using them

A method of modulating flow of a fluid in a chromatography system including a microfluidic device comprising a laminated wafer body comprising an internal microchannel fluidically coupled to a first port and a second port, wherein the microfluidic device is fluidically coupled to a first switching valve through the first port of the microfluidic device and to a second switching valve through the second port of the microfluidic device, the method comprising:

• independently actuating the first switching valve and the second switching valve between a first position and a second position, the first position of the first switching valve permitting fluid flow from a switching gas source to the first port of the microfluidic device, the first position of the second switching valve permitting fluid flow from the gas source to the second port of the microfluidic device, in which the actuation of the first switching valve and the second switching valve is configured to provide three-way switching using the microfluidic device;
• and
• altering fluid pressure to permit a sample to flow to a first outlet port of the microfluidic device in a first state of the microfluidic device, in which the first outlet port is fluidically coupled to the first port and the second port through the internal microchannel, and to permit the sample to flow to a second outlet port of the microfluidic device in a second state of the microfluidic device, in which the second outlet port is fluidically coupled to the first port and the second port through the internal microchannel.