Optical approach for microfluidic DNA electrophoresis detection

• US 20110229897A1
• Filed: 03/04/2011
• Published: 09/22/2011
• Est. Priority Date: 06/04/2009
• Status: Active Grant

• Current Assignee: Leidos Innovations Technology, Inc., Microgem NZ Limited, University of Virginia Patent Foundation (University of Virginia)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Root, Brian E., Bell, H.Randall, Landers, James P., Pettit, John W., Scott, Orion N., Bienvenue, Joan M., Marchiarullo, Daniel J.
• Granted Patent: US 9,067,207 B2
• Time in Patent Office: Days
• US Class Current: 435/6.12
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/087 Multiple sequential chambers
• CPC Class Codes: B01L 2400/0421 electrophoretic flow
• CPC Class Codes: B01L 3/502753 characterised by bulk separation arrangements on lab-on-a-chip devices, e.g. for filtration or centrifugation separation in general B01D; microapparatus for analysis using electrophoresis G01N27/44791; sample preparation G01N1/28
• CPC Class Codes: B01L 7/525 with physical movement of samples between temperature zones
• CPC Class Codes: G01N 2021/4186 Phase modulation imaging
• CPC Class Codes: G01N 27/44791 Microapparatus sample containers with integrated microfluidic structures B01L3/5027
• CPC Class Codes: G01N 29/32 Arrangements for suppressing undesired influences, e.g. temperature or pressure variations , compensating for signal noise

Abstract

Aspects of the disclosure provides a DNA analyzer to facilitate an integrated single-chip DNA analysis. The DNA analyzer includes an interface for coupling a microfluidic chip to the DNA analyzer. The microfluidic chip includes a first domain configured for polymerase chain reaction (PCR) amplification of DNA fragments, and a second domain fluidically coupled to the first domain to receive the DNA fragments and perform electrophoretic separation of the DNA fragments. The DNA fragments are tagged with fluorescent labels. The DNA analyzer includes a detection module to excite the fluorescent labels to emit fluorescence and detect the emitted fluorescence. The detection module includes a laser source, a set of optical elements, a filter module and a photo-detector.

Claims

1. A DNA analyzer, comprising:

an interface for coupling a microfluidic chip to the DNA analyzer, wherein the microfluidic chip includes;

a first domain configured for polymerase chain reaction (PCR) amplification of DNA fragments, the DNA fragments being tagged with fluorescent labels; and

a second domain fluidically coupled to the first domain to receive the DNA fragments, the second domain having a separation channel for electrophoretic separation of the DNA fragments; and

a detection module optically coupled with the microfluidic chip that includes;

a laser source configured to generate a laser beam;

a set of optical elements configured to direct the laser beam to the separation channel to excite the fluorescent labels to emit fluorescence while the DNA fragments migrate in the separation channel, and to collect the emitted fluorescence into an optical signal;

a filter module configured to filter the optical signal to allow a first portion of the optical signal having a first wavelength to pass; and

a photo-detector configured to generate an electrical detection signal in response to the filtered optical signal.

2. The DNA analyzer of claim 1, wherein the photo-detector further comprises:

a photo-multiplier tube configured to generate the electrical detection signal in response to the filtered optical signal.

3. The DNA analyzer of claim 1, wherein the set of optical elements further comprise:

an objective lens aligned with the separation channel to direct the laser beam to the separation channel and to collect the emitted fluorescence from the separation channel.

4. The DNA analyzer of claim 3, further comprising

a motor configured to align the objective lens to the separation channel.

5. The DNA analyzer of claim 1, wherein the filter module further comprises:

an acousto-optic tunable filter (AOTF) configured to filter the optical signal to allow the first portion of the optical signal having the first wavelength to pass based on an electrical tuning signal having a first tuning frequency, the first wavelength satisfying a matching condition of the AOTF with the first tuning frequency.

6. The DNA analyzer of claim 5, further comprising:

a controller configured to generate a control signal indicative of the first tuning frequency; and

a synthesizer configured to generate the electrical tuning signal having the first tuning frequency based on the control signal.

7. The DNA analyzer of claim 6, wherein

the controller adjusts the control signal to be indicative of a second tuning frequency, and that causes:

the synthesizer generates the electrical tuning signal having the second tuning frequency based on the control signal; and

the AOTF filters the optical signal to allow a second portion of the optical signal having a second wavelength to pass based on the electrical tuning signal, the second wavelength satisfying the matching condition of the AOTF with the second tuning frequency.

8. The DNA analyzer of claim 5, further comprising:

a modulation signal generator configured to generate a modulation signal having a modulation frequency, and a reference signal having the modulation frequency, the modulation signal being used by the AOTF to modulate the filtered optical signal; and

a phase-sensitive detector configured to receive the reference signal and the electrical detection signal corresponding to the modulated filtered optical signal, and demodulate the electrical detection signal based on the reference signal.

9. The DNA analyzer of claim 1, further comprising:

a pressure module configured to flow liquid in the microfluidic chip;

a thermal module configured to induce thermal cycling at the first domain of the microfluidic chip for the PCR amplification;

a power module configured to generate voltages to be applied to the second domain of the microfluidic chip for the electrophoretic separation; and

a controller module configured to control the pressure module, the thermal module, the power module, and the detection module according to a control procedure to act on the microfluidic chip for a single-chip DNA analysis.

10. A method of DNA analysis, comprising:

selecting a first wavelength corresponding to a first fluorescent label used to label DNA fragments during polymerase chain reaction (PCR) amplification in a first domain of a microfluidic chip, the DNA fragments having been fluidically directed from the first domain to a second domain of the microfluidic chip having a separation channel for electrophoretic separation;

exciting at least the first fluorescent label to emit fluorescence in the second domain; and

tuning a detection module to detect the emitted fluorescence having the first wavelength.

11. The method of claim 10, wherein exciting the first fluorescent label to emit the fluorescence in the second domain further comprises:

generating a laser beam; and

directing the laser beam to the separation channel to excite the first fluorescent label to emit the fluorescence while the DNA fragments migrate in the separation channel.

12. The method of claim 11, further comprising:

collecting the emitted fluorescence into an optical signal.

13. The method of claim 12, wherein tuning the detection module to detect the emitted fluorescence having the first wavelength, further comprises:

generating an electrical tuning signal having a first tuning frequency;

providing the electrical tuning signal to an acousto-optic tunable filter (AOTF) in the detection module to filter the optical signal and pass a first portion of the optical signal having the first wavelength, the first wavelength satisfying a matching condition of the AOTF with the first tuning frequency; and

detecting the filtered optical signal.

14. The method of claim 13, further comprising:

selecting a second wavelength corresponding to a second fluorescent label used to label the DNA fragments during the (PCR) amplification in the first domain;

adjusting the electrical tuning signal to have a second tuning frequency; and

causing the AOTF to filter the optical signal and pass a second portion of the optical signal having the second wavelength, the second wavelength satisfying the matching condition of the AOTF with the second tuning frequency.

15. A DNA analyzer, comprising:

an interface for coupling a microfluidic chip to the DNA analyzer, wherein the microfluidic chip includes;

a first domain configured for polymerase chain reaction (PCR) amplification of DNA fragments, the DNA fragments being tagged with fluorescent labels; and

a second domain fluidically coupled to the first domain to receive the DNA fragments, the second domain having a separation channel for electrophoretic separation of the DNA fragments;

a detection module optically coupled with the microfluidic chip that includes;

a laser source configured to generate a laser beam;

a passive optics module including passive units that are pre-configured to receive the laser beam and transmit the laser beam; and

an active optics module including at least an active unit to focus the laser beam to the separation channel to excite the fluorescent labels to emit fluorescence while the DNA fragments migrate in the separation channel, and to collect the emitted fluorescence from the separation channel into an optical signal for return, wherein the passive optics module includes;

a filter module configured to filter the optical signal to allow a first portion of the optical signal having a first wavelength to pass; and

a photo-detector configured to generate an electrical detection signal in response to filtered optical signal.

16. The DNA analyzer of claim 15, wherein the photo-detector further comprises:

a photo-multiplier tube configured to generate the electrical detection signal in response to the filtered optical signal.

17. The DNA analyzer of claim 15, wherein the active optics module further comprises:

an objective lens aligned with the separation channel to direct the laser beam to the separation channel and to collect the emitted fluorescence from the separation channel.

18. The DNA analyzer of claim 17, wherein the active optics module further comprises:

a motor configured to align the objective lens to the separation channel.

19. The DNA analyzer of claim 15, wherein the filter module further comprises:

an acousto-optic tunable filter (AOTF) configured to filter the optical signal to allow the first portion of the optical signal having the first wavelength to pass based on an electrical tuning signal having a first tuning frequency, the first wavelength satisfying a matching condition of the AOTF with the first tuning frequency.

20. The DNA analyzer of claim 19, further comprising:

a controller configured to generate a control signal indicative of the first tuning frequency; and

a synthesizer configured to generate the electrical tuning signal having the first tuning frequency based on the control signal.

21. The DNA analyzer of claim 20, wherein

the controller adjusts the control signal to be indicative of a second tuning frequency, and that causes:

the synthesizer generates the electrical tuning signal having the second tuning frequency; and

the AOTF filters the optical signal to allow a second portion of the optical signal having a second wavelength to pass based on the electrical tuning signal, the second wavelength satisfying the matching condition of the AOTF with the second tuning frequency.

22. The DNA analyzer of claim 19, further comprising:

a modulation signal generator configured to generate a modulation signal having a modulation frequency, and a reference signal having the modulation frequency, the modulation signal being used by the AOTF to modulate the filtered optical signal; and

a phase-sensitive detector configured to receive the reference signal and the electrical detection signal corresponding to the modulated filtered optical signal, and demodulate the electrical detection signal based on the reference signal.

23. The DNA analyzer of claim 15, further comprising:

a pressure module configured to flow liquid in the microfluidic chip;

a thermal module configured to induce thermal cycling at the first domain of the microfluidic chip for the PCR amplification;

a power module configured to generate voltages to be applied to the second domain of the microfluidic chip for the electrophoretic separation; and

a controller module configured to control the pressure module, the thermal module, the power module, and the detection module according to a control procedure to act on the microfluidic chip for a single-chip DNA analysis.