Parallel sample loading and injection device for multichannel microfluidic devices
A sample load and injection device ( 10 ) includes sample introduction capillaries ( 11 ) attached to a microfluidic device ( 12 ). Sample introduction capillaries ( 11 ) are connected to sample introduction channels ( 18 ). Sample introduction capillaries ( 18 ) are connected to separation channels ( 20 ) at connection points ( 21 ). At a defined distance along the separation channels ( 20 ), auxilliary channels ( 23 ) originate at connection points ( 24 ). The sample load and injection device includes cover plate ( 28 ) which has connecting channels ( 26, 32 ). Connecting channel ( 26 ) is associated with ends ( 24 ) of sample introduction channels ( 18 ). Connecting channel ( 32 ) is associated with ends ( 20 ).
1. A sample load and injection device for the parallel transfer of liquid samples into channels of a multichannel microfluidic device, said sample load and injection device comprising:
multiple sample introduction capillaries, each said introduction capillary having an inlet end and an outlet end, the inlet end of each said individual capillary being external to said sample load and injection device and capable of being placed in alignment with one of multiple samples in a sample holder, and the outlet end of each said introduction capillary opening to an introduction channel in said sample load and injection device, said introduction channel having an introduction channel end in said sample load and injection device;
a sample channel originating at each said introduction channel;
an auxiliary channel originating at each said sample channel and ending at an auxiliary channel end in said sample load and injection device;
a connecting channel connecting said introduction channel ends; and
a connecting channel connecting said auxiliary channel ends, said connecting channel for said introduction channel ends and said connecting channel for said auxiliary channel ends each terminating at one end at a surface of said sample load and injection device, wherein each said connecting channel is configured for connection to a source of positive or negative pressure or to a source for applying an electric field across any channel segment.
2. The sample load and injection device of claim 1 , wherein said sample channels and said auxiliary channels are smaller in internal diameter than are said introduction channels.
3. The sample load and injection device of claim 1 , wherein said connecting channels are resident in a cover plate that is separable from the main body of said sample load and injection device.
4. The sample load and injection device of claim 1 , wherein said one or more of said sample channels is configured for separation of a loaded sample.
5. The sample load and injection device of claim 1 , wherein said sample load and injection device is integral with a multichannel microfluidic device.
6. The sample load and injection device of claim 1 , wherein said sample load and injection device is separable from but attachable to a multichannel microfluidic device.
7. A method for the parallel injection of samples into separate channel systems within a microfluidic device, said method comprising the steps of:
providing the sample load and injection device of claim 1 ;
positioning said sample load and injection device adjacent a sample holder having multiple individual samples so that individual sample introduction capillaries of said device are immersed into individual samples in said sample holder;
applying a vacuum to said connecting channel connecting said auxiliary channel ends, wherein said individual samples are pulled through said introduction channels and a portion of each of said separation channels and into said auxiliary channels; and
replacing said individual samples in said sample holder by a reservoir containing a background electrolyte and applying a vacuum to said connecting channel connecting said introduction channel ends, whereby the portions of said samples remaining in said introduction capillaries and said introduction channels are replaced by said background electrolyte.
8. The method of claim 7 , wherein, prior to the step of applying a vacuum to said connecting channel connecting said auxiliary channel ends, said method further comprises the step of applying a vacuum to said connecting channel connecting said introduction channel ends, wherein said individual samples simultaneously fill said individual sample introduction capillaries and associated sample introduction channels.
9. The method of claim 7 or claim 8 , wherein, prior to said positioning step, said method further comprises the step of flushing said channels of said device with background electrolyte.
10. The method of claim 7 or claim 8 , wherein said sample introduction capillaries comprise a coating or a packing material and said samples are exposed to said coating or to said packing material during passage through said introduction capillaries.
11. The method of claim 7 or claim 8 , wherein samples in said introduction capillaries are subjected to an isoelectrofocusing step.