Microfluidic devices for electrophoretic analysis of materials
The present invention provides a microfluidic system for electrophoretic analysis of materials in the fields of chemistry, biochemistry, biotechnology, molecular biology and numerous other fields. Light absorbance signals are received by a photodetector from periodically spaced regions along a channel in the microfluidic system. The signals received by the photodetector are modulated by the movement of species bands through the channel under electrophoretic forces. By Fourier analysis, the velocity of each species band is determined, and identification of the species is made based on its electrophoretic mobility in the channel.
1 . A method of detecting species bands in a separation conduit, comprising:
directing light from a light source through a mask at a plurality of discrete regions of the separation conduit, the plurality of discrete regions containing a plurality of species bands, the light source selected to radiate at a wavelength that is absorbed by the species bands; and
simultaneously detecting light absorbance from said plurality of species bands in said plurality of discrete regions.
2 . The method of claim 1 , wherein the plurality of species bands are electrophoresed through the separation conduit during said directing and simultaneously detecting steps.
3 . The method of claim 2 , wherein light absorbance from the plurality of species bands moving in the separation conduit causes a varying signal to be detected.
4 . The method of claim 3 , further comprising determining a rate at which the plurality of species bands are moving in the separation conduit by monitoring a frequency at which light absorbance is detected in the plurality of regions of the separation conduit.
5 . The method of claim 1 , wherein the separation conduit comprises a channel in a microfluidic device.
6 . The method of claim 1 , wherein the species bands comprise nucleic acids.
7 . The method of claim 6 , wherein the light source is selected to radiate at a wavelength of 280 nm.
8 . The method of claim 1 , wherein the species bands comprise polynucleotides.
9 . The method of claim 8 , wherein the light source is selected to radiate at a wavelength of 260 nm.
10 . A method of detecting species bands in a separation conduit, comprising:
directing light from a light source at a plurality of discrete regions of the separation conduit, the plurality of discrete regions containing a plurality of species bands, the light source selected to radiate at a wavelength that is absorbed by the species bands; and
simultaneously detecting light absorbance from said plurality of species bands in said plurality of discrete regions.
11 . The method of claim 10 , wherein the plurality of discrete regions are each between about 50 μm and 500 μm long along the separation conduit.
12 . The method of claim 10 , wherein the light is direct through a pair of slits.
13 . The method of claim 12 , wherein the slits are parallel to each other and perpendicular to the length of the separation conduit.
14 . The method of claim 12 , wherein the light source is a coherent light source.
15 . The method of claim 10 , wherein the separation conduit comprises a channel in a microfluidic device.
16 . A system for detecting separated species bands, comprising:
a separation conduit for separating species bands;
a light absorbance detection system, comprising:
a light source for directing light at a plurality of regions of the separation conduit at a wavelength that is absorbed by the species bands;
a mask positioned between the light source and the separation conduit for directing the light at a plurality of discrete regions of the separation conduit; and
a detector oriented to simultaneously detect light absorbance from the plurality of regions of the separation conduit.
17 . The system of claim 16 , wherein the separation conduit comprises a channel in a microfluidic device.
18 . The system of claim 16 , wherein the detector is selected from a group consisting of a photomultiplier tube, a photodiode, and a CCD array.
19 . The system of claim 16 , further comprising:
a computer unit for determining a rate at which the plurality of species bands are moving in the separation conduit by monitoring a frequency at which light absorbance is detected in the plurality of regions of the separation conduit.
20 . The system of claim 16 , further comprising:
a computer unit with a calibrated look-up table.