Droplet Actuator Devices, Configurations, and Methods for Improving Absorbance Detection

• US 20100118307A1
• Filed: 03/13/2008
• Published: 05/13/2010
• Est. Priority Date: 03/13/2007
• Status: Active Grant

• Current Assignee: Advanced Liquid Logic, Inc. (Illumina Incorporated)
• Original Assignee: Advanced Liquid Logic, Inc. (Illumina Incorporated)
• Inventors: Wang, Tih-Hong, Pamula, Vamsee K., Srinivasan, Vijay, Pollack, Michael G.
• Granted Patent: US 8,208,146 B2
• Time in Patent Office: Days
• US Class Current: 356/436
• CPC Class Codes: G01N 2021/035 Supports for sample drops
• CPC Class Codes: G01N 2021/036 transformable, modifiable
• CPC Class Codes: G01N 21/0303 Optical path conditioning in cuvettes, e.g. windows; adapted optical elements or systems; path modifying or adjustment G01N21/031 - G01N21/15 take precedence
• CPC Class Codes: G01N 21/031 Multipass arrangements
• CPC Class Codes: G01N 2201/08 Optical fibres; light guides

Abstract

Devices, configurations and methods for improving absorbance detection are provided. For example, methods and devices are provided for determining the absorbance of a droplet, e.g., a droplet on a droplet actuator, by providing an elongated light path through the droplet.

Claims

1. A method of determining the absorbance of a droplet, the method comprising:

(a) providing a droplet actuator comprising;

(i) two substrates separated to form a gap; and

(ii) a droplet positioned in the gap and having a droplet height established by surfaces of the two substrates;

(b) providing a light source arranged to transmit light through the droplet and a sensor arranged to sense light from the droplet, thereby creating a light path through the droplet and substantially parallel with the surfaces of the substrates wherein the light path through the droplet is greater than the droplet height;

(c) directing light from the light source through the droplet and to the sensor;

(d) sensing the light energy at the sensor; and

(e) determining from the sensed light energy an optical property of the droplet.

2. The method of claim 1 wherein the path through the droplet is less than 1 cm.

3. A method of determining the absorbance of a droplet, the method comprising:

(a) providing a droplet actuator comprising;

(i) two substrates separated to form a gap; and

(ii) a droplet positioned in the gap and having a droplet height established by surfaces of the two substrates;

(b) providing a light source arranged to transmit light through the droplet and a sensor arranged to sense light from the droplet, thereby creating a light path through the droplet wherein the light path through the droplet is greater than the droplet height;

(c) conducting droplet operations to elongate the droplet along the light path through the droplet;

(d) directing light from the light source through the droplet and to the sensor;

(e) sensing the light energy at the sensor; and

(f) determining from the sensed light energy an optical property of the droplet.

4. The method of claim 3 wherein the path through the droplet is less than 1 cm.

5. The method of claim 3 further comprising positioning the droplet within an aperture of a substrate, thereby increasing the droplet height.

6. The method of claim 3 further comprising elongating the droplet along a central vertical axis of the droplet defined by the path of light using an electrode.

7. The method of claim 3 wherein the light path through the droplet is substantially perpendicular to the droplet height and/or surfaces of the substrates.

8. The method of claim 3 wherein the light path through the droplet is at an angle that is substantially acute with respect to one of the surfaces establishing the droplet height.

9. The method of claim 3 further comprising conducting a droplet operation and/or adding additional droplet to the droplet in order to increase the height of the droplet.

10. The method of claim 3 further comprising a droplet arranged in the gap in a path of the light source, wherein:

(a) the droplet comprises beads; and

(b) the optical property of the droplet is indicative of an optical property of the beads.

11. The method of claim 3 further comprising a droplet arranged in the gap in a path of the light source, wherein:

(a) the droplet comprises biological cells; and

(b) the optical property of the droplet is indicative of an optical property of the biological cells.

12. The method of claim 3 further comprising:

(a) a droplet in the gap in a path of the light source; and

(b) filler fluid surrounding the droplet.

13. The method of claim 3 wherein the droplet comprises beads, and the optical property of the droplet is indicative of an optical property of the beads.

14. The method of claim 3 wherein the droplet comprises biological cells, and the optical property of the droplet is indicative of an optical property of the biological cells.

15. The method of claim 3 further comprising providing the droplet in a filler fluid having different light refractive characteristics than light refractive characteristics of the droplet, that light incident upon the filler fluid does not reach the sensor.

16. The method of claim 3 further comprising providing the droplet in a filler fluid having different light absorbing characteristics than light absorbing characteristics of the droplet, that light in a wavelength of interest passes through the droplet to the sensor but does not pass through the filler fluid to the sensor.

17. A method of determining the absorbance of a droplet, the method comprising:

(a) providing a droplet actuator comprising;

(i) two substrates separated to form a gap; and

(ii) a droplet positioned in the gap and having a droplet height established by surfaces of the two substrates;

(b) providing a light source arranged to transmit light through the droplet and a sensor arranged to sense light from the droplet, thereby creating a light path through the droplet wherein the light path through the droplet is greater than the droplet height, wherein the source and the sensor are offset from a central vertical axis of the droplet and the source and the sensor are arranged on opposite sides of the droplet actuator;

(c) directing light from the light source through the droplet and to the sensor;

(d) sensing the light energy at the sensor; and

(e) determining from the sensed light energy an optical property of the droplet.

18. The method of claim 17 wherein the path through the droplet is less than 1 cm.

19. The method of claim 17 further comprising providing the light source and the sensor are offset from one another in relation to a central vertical axis of the droplet.

20. The method of claim 17 wherein the light path through the droplet is at least two times greater than the droplet height.

21. A method of determining the absorbance of a droplet, the method comprising:

(a) providing a droplet actuator comprising;

(i) two substrates separated to form a gap; and

(ii) a droplet positioned in the gap and having a droplet height established by surfaces of the two substrates;

(b) providing a light source arranged to transmit light through the droplet and a sensor arranged to sense light from the droplet, thereby creating a light path through the droplet wherein the light path through the droplet is greater than the droplet height;

(c) using diffractive material to direct light from the light source through the droplet and to the sensor;

(d) sensing the light energy at the sensor; and

(e) determining from the sensed light energy an optical property of the droplet.

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30. A method of determining the absorbance of a droplet, the method comprising:

(a) providing a droplet actuator comprising;

(i) two substrates separated to form a gap; and

(ii) a droplet positioned in the gap and having a droplet height established by surfaces of the two substrates, wherein the droplet is mixed with a reagent at a location remote from the substrate;

(b) providing a light source arranged to transmit light through the droplet and a sensor arranged to sense light from the droplet, thereby creating a light path through the droplet wherein the light path through the droplet is greater than the droplet height.

(c) directing light from the light source through the droplet and to the sensor;

(d) sensing the light energy at the sensor; and

(e) determining from the sensed light energy an optical property of the droplet.

31. The method of claim 30 wherein the light path through the droplet is less than 1 cm.

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