Method of improving sensor detection of target molcules in a sample within a fluidic system

• US 7,919,330 B2
• Filed: 06/15/2006
• Issued: 04/05/2011
• Est. Priority Date: 06/16/2005
• Status: Expired due to Fees

• Current Assignee: Advanced Liquid Logic, Inc. (Illumina Incorporated)
• Original Assignee: Advanced Liquid Logic, Inc. (Illumina Incorporated)
• Inventors: de Guzman, Peter Patrick, Kim, Chang-Jin, Yi, Uichong Brandon, Liu, Wayne Po-Wen
• Primary Examiner(s): Chin; Christopher L
• Application Number:
  US11/917,655
• Publication Number:
  US 20090042319A1
• Time in Patent Office: 1,755 Days
• Field of Search: None
• US Class Current: 436/514
• CPC Class Codes: B01F 33/3021 the components to be mixed being combined in a single independent droplet, e.g. these droplets being divided by a non-miscible fluid or consisting of independent droplets
• CPC Class Codes: B01F 33/3031 using electro-hydrodynamic [EHD] or electro-kinetic [EKI] phenomena to mix or move the fluids
• CPC Class Codes: B01L 2200/0605 Metering of fluids
• CPC Class Codes: B01L 2200/0678 Facilitating or initiating evaporation
• CPC Class Codes: B01L 2200/10 Integrating sample preparation and analysis in single entity, e.g. lab-on-a-chip concept
• CPC Class Codes: B01L 2300/0627 Sensor or part of a sensor is integrated
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2400/0427 Electrowetting
• CPC Class Codes: B01L 3/502792 for moving individual droplets on a plate, e.g. by locally altering surface tension
• CPC Class Codes: G01N 33/54373 involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
• CPC Class Codes: Y10T 436/10 Composition for standardization, calibration, simulation, stabilization, preparation or preservation; processes of use in preparation for chemical testing
• CPC Class Codes: Y10T 436/25 including sample preparation

Abstract

Methods of improving microfluidic assays are disclosed. Assays can be improved (better signal to noise ratio) by using sessile drop evaporation as an analyte concentration step (enhanced signal) and repeated passes of wash droplets as a means to reduce non-specific binding (noise reduction). In addition multiple massively parallel analyses improve the statistical precision of the analyses.

Claims

1. A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor; and

washing the sensing site by moving at least one droplet of a wash solution over the sensing site, wherein moving each discrete droplet comprises electrowetting.

2. The method according to claim 1, wherein the step of moving each droplet does not require valves, pumps or acoustic effects.

3. The method according to claim 1, wherein the target molecules are not denatured by the method.

4. The method according to claim 1, wherein a plurality of sensing sites are provided in parallel and a plurality of identical activities are undertaken simultaneously, one activity for each sensing site.

5. The method according to claim 4, wherein the activities at the plurality of parallel sensing sites improve statistical accuracy of detection of target molecules.

6. The method of claim 1, wherein moving each discrete droplet over a sensing site comprises transporting each discrete droplet to interact with each sensing site in a controlled manner.

7. The method of claim 1, further comprising moving droplets of wash to, and agitating over, sensor surfaces to remove non-target and unbound target molecules.

8. The method of claim 1, further comprising repeated driving of droplets of wash over the sensor.

14. The method of claim 1, A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor, wherein each discrete droplet is comparable in size to the sensing site, and wherein moving each discrete droplet comprises electrowetting.

9. A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor; and

moving at least one droplet of a substrate reaction solution or marker second antibody solution over the sensing site, wherein moving each discrete droplet comprises electrowetting.

10. A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor; and

agitating said droplet at the sensing site, wherein moving each discrete droplet comprises electrowetting.

11. A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor; and

concentrating said droplet at the sensing site by means of evaporation, wherein moving each discrete droplet comprises electrowetting.

12. The method according to claim 11, wherein the step of concentrating comprises creating a residual sessile droplet at the sensing site.

13. A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor; and

moving at least one droplet containing non-specific molecules over the sensing site to act as a reference for non-specific binding, wherein moving each discrete droplet comprises electrowetting.

15. A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor, wherein moving each discrete droplet over a sensing site comprises moving each discrete droplet over the sensor in a plurality of directions, and wherein moving each discrete droplet further comprises electrowetting.

16. A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor, wherein moving each discrete droplet over a sensing site comprises holding the discrete droplet stationary over the sensor for a given time and moving the discrete droplet over the sensor at various velocities, and wherein moving each discrete droplet further comprises electrowetting.

17. A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor, wherein moving each discrete droplet over a sensing site comprises driving each discrete droplet over the sensor in a manner which produces localized agitation effects, and wherein moving each discrete droplet further comprises electrowetting.

18. A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor, wherein moving each discrete droplet over a sensing site comprises driving each discrete droplet over the sensor in a manner which brings particles in free suspension or molecules dissolved within the discrete droplet and/or residing on the liquid/air and liquid/surface interfaces of the discrete droplet into proximity to the sensor, and wherein moving each discrete droplet further comprises electrowetting.

19. A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor, wherein moving each discrete droplet over a sensing site comprises driving each discrete droplet over the sensor in a manner which mitigates adsorption of non-target molecules at the sensor site, and wherein moving each discrete droplet further comprises electrowetting.

20. A method for improving sensor detection of target molecules in a sample within a fluidic system comprising the steps of breaking the sample into a series of discrete droplets;

moving each discrete droplet over a sensing site of a sensor thereby improving detection by furnishing multiple signals from the sensor, the method further comprising formation and evaporation of a sessile droplet, and wherein moving each discrete droplet comprises electrowetting.