Chromatography systems and methods using them
Certain embodiments described herein are directed to chromatography systems that include a microfluidic device. The microfluidic device can be fluidically coupled to a switching valve to provide for selective control of fluid flow in the chromatography system. In some examples, the microfluidic device may include a charging chamber, a bypass restrictor or other features that can provide for added control of the fluid flow in the system. Methods of using the devices and methods of calculating lengths and diameters to provide a desired flow rate are also described.
1. A microfluidic device comprising:
a laminated wafer comprising an internal microchannel formed from laminating individual metal layers to each other, the laminated wafer comprising a first port, a second port and a third port each fluidically coupled to the internal microchannel, wherein each of the first port, the second port and the third port permits fluid flow into and out of the internal microchannel; and
a bypass restrictor that fluidically couples the second port and the third port to each other and is configured to restrict fluid flow;
wherein a first end of the bypass restrictor is fluidically coupled to the internal microchannel at a first location of the internal microchannel that is between the first port and the second port; and
wherein a second end of the bypass restrictor is fluidically coupled to the internal microchannel at a second location of the internal microchannel that is between the first port and the third port.
2. The microfluidic device of claim 1 , wherein the bypass restrictor is external to the laminated wafer.
3. The microfluidic device of claim 2 , wherein the bypass restrictor comprises a solenoid valve.
4. The microfluidic device of claim 2 , wherein the first port is configured to provide effluent from a chromatography column into the internal microchannel.
5. The microfluidic device of claim 2 , wherein the bypass restrictor is configured to bypass another port of the laminated wafer.
6. The microfluidic device of claim 2 , wherein a diameter of the internal microchannel is different than a diameter of the bypass restrictor.
7. The microfluidic device of claim 6 , wherein a diameter of the internal microchannel is greater than the diameter of the bypass restrictor.
8. The microfluidic device of claim 7 , wherein the diameter of the internal microchannel is at least two times larger than the diameter of the bypass restrictor.
9. The microfluidic device of claim 8 , wherein a diameter of the diameter of the internal microchannel is at least four times larger than the diameter of the bypass restrictor.
10. The microfluidic device of claim 7 , wherein the diameter of the internal microchannel is between 300 and 700 microns.
11. The microfluidic device of claim 7 , wherein the diameter of the internal microchannel is between 100 and 200 microns.
12. The microfluidic device of claim 7 , wherein the length of the bypass restrictor is between 5 and 30 mm.
13. The microfluidic device of claim 1 , wherein the third port is configured to receive a switching gas.
14. The microfluidic device of claim 13 , further comprising a fourth port configured to provide sample exiting the laminated wafer to a downstream component fluidically coupled to the fourth port.
15. The microfluidic device of claim 1 , wherein the laminated wafer further comprises a fourth port and a fifth port.
16. The microfluidic device of claim 15 , wherein each of the second port and the third port is configured to receive a switching gas from a gas source.
17. The microfluidic device of claim 16 , wherein the microfluidic device is configured, at a first pressure provided using the switching gas introduced into the second port and the third port, to provide sample from the fourth port of the laminated wafer to a downstream component fluidically coupled to the fourth port.
18. The microfluidic device of claim 1 , wherein each layer of the laminated wafer comprises stainless steel.
19. The microfluidic device of claim 1 , wherein a length of the bypass restrictor (L r ) is calculated using the following equation:
L
r
=
[
π
×
T
a
×
d
r
4
256
×
F
a
×
p
a
×
(
p
i
2
-
p
or
2
)
-
T
r
2
×
η
r
2
×
L
r
2
]
T
r
1
×
η
r
1
+
L
r
2
where T a is ambient temperature, d r is an internal diameter of the bypass restrictor, F a is the flow rate, P a is ambient pressure, p i is inlet pressure, p or is outlet pressure, T r2 is a temperature of a detector, η r2 is a viscosity of carrier gas at the temperature of the detector, L r2 is a length of the bypass restrictor inside the detector, T r1 is a temperature of the bypass restrictor, and η r1 is a viscosity of carrier gas at the temperature of the bypass restrictor.
20. A laminated wafer microfluidic device configured to provide a received sample to a plurality of different ports of the laminated wafer microfluidic device depending on a gas pressure within the laminated wafer microfluidic device, wherein the laminated wafer microfluidic device comprises:
an internal microchannel;
an external fluid connection that fluidically couples at least two ports of the laminated wafer microfluidic device;
a sample inlet port fluidically coupled to the internal microchannel; and
at least one switching gas port fluidically coupled to the internal microchannel, the switching gas port configured to provide a gas into the internal microchannel to control the gas pressure within the laminated wafer microfluidic device to direct flow of the received sample;
wherein an end of the external fluid connection is fluidically coupled to the internal microchannel at a location of the internal microchannel that is between the inlet port and the switching gas port.