Droplet actuator devices, configurations, and methods for improving absorbance detection

• US 8,208,146 B2
• Filed: 03/13/2008
• Issued: 06/26/2012
• Est. Priority Date: 03/13/2007
• Status: Expired due to Fees

• Current Assignee: Advanced Liquid Logic, Inc. (Illumina Incorporated)
• Original Assignee: Advanced Liquid Logic, Inc. (Illumina Incorporated)
• Inventors: Srinivasan, Vijay, Pamula, Vamsee K., Pollack, Michael G., Wang, Tih-Hong
• Primary Examiner(s): NGUYEN, SANG H
• Application Number:
  US12/529,025
• Publication Number:
  US 20100118307A1
• Time in Patent Office: 1,566 Days
• Field of Search: 356432-437, 250/459.1, 250/458.1, 437/19, 422/82.05, 422/81, 422/89, 435/6, 435/91.1, 435/91.2
• 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, and further wherein the droplet is arranged in the gap in the ligth path of the light source, wherein;

(i) the droplet comprises beads; and

ii) the optical property of the droplet is indicative of an optical property of the beads;

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

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

(e) using a processor, 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, and further wherein the droplet is arranged in the gap in the light path of the light source, wherein;

(i) the droplet comprises biological cells; and

(ii) the optical property of the droplet is indicative of an optical property of the biological cells;

(c) conducting droplet operations which 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) using a processor, 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 wherein the elongating comprises 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 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 wherein the elongating comprises conducting a droplet operation which increases the height of the droplet.

10. 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.

11. 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.

12. 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.