Non-destructive read operations with dynamically growing images

Patent metadata

Field	Value
Publication number	US-10104307-B2
Application number	US-201715667435-A
Country	US
Kind code	B2
Filing date	Aug 2, 2017
Priority date	Dec 13, 2013
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

Methods and digital imaging devices disclosed herein are adapted to capture images of a specimen in a chemical reaction using a series of short exposures of light emissions from the specimen over a period of time. The series of short exposures is captured using an array of pixels of an image sensor in the digital imaging device that are configured for performing continuous non-destructive read operations to read out a set of non-destructive read images of the specimen from the pixel array. In one embodiment, images are captured by delaying the read out until at or near the end of the chemical reaction to reduce read noise in the images. The signals read out from the image sensor can be continuously monitored and the capturing of images can be discontinued either automatically or based on a command from a user. The captured images can then be displayed in a graphical display.

First claim

What is claimed is:

1. A method of capturing digital images of a specimen in a chemical reaction comprising:
capturing, by an imaging device, a series of short exposures of light emissions from the specimen over a period of time during the reaction, wherein captured images of the specimen grow dynamically over the period of time as the number of exposures increases,
wherein the series of short exposures is captured using an array of pixels of an image sensor of a digital imaging device configured to perform continuous non-destructive read operations to read out a set of signals representing non-destructive read images of the specimen from the array of pixels of the image sensor, and wherein reading out the set of signals is delayed until the end of the period of time to reduce read noise in the set of non-destructive read images;
storing in a memory of the digital imaging device emission profile data of multiple different assays including information relating to when an emission for a particular assay will begin rapidly declining;
monitoring, by the imaging device, the set of signals read out from the image sensor; and
discontinuing capturing images of the specimen, by the imaging device, upon receiving a command, wherein the command is generated automatically based at least in part on the emission profile for the particular assay in which the chemical reaction occurs, or is based on input from a user of the digital imaging device.

2. The method of claim 1 further comprising displaying the captured images of the specimen in a graphical display.

3. The method of claim 1 wherein the digital imaging device comprises a complementary metal-oxide-semiconductor (“CMOS”) digital imaging device capable of performing non-destructive read operations.

4. The method of claim 3 wherein images captured using the CMOS digital imaging device exhibit minimal blooming due to over-saturation from bright pixels, and wherein long exposures of bright bands of light emitted from the specimen are performed even if the bright bands are located in proximity to faint bands emitted from the specimen.

5. The method of claim 1 further comprising increasing a dynamic range of the captured images of the specimen by combining data from shorter-time read images of the set of non-destructive read images for brighter areas of the specimen with data from longer-time read images of the set of non-destructive read images for dimmer areas of the specimen.

6. The method of claim 1 further comprising:
expanding bit depth of the captured images; and
calculating a signal for one or more bright bands of emissions from the specimen based on a ratio of the period of time of exposure of emissions from the specimen taken by the digital imaging device to a total time of the exposure of emissions from the specimen obtained from the emission profile data.

7. The method of claim 1 wherein the emission profile data is either known beforehand or measured by a user of the digital imaging device.

8. The method of claim 1 further comprising using the emission profile data to improve auto-exposure of the particular specimen.

9. The method of claim 1 further comprising querying the user of the digital imaging device when an emission of a specimen is at or near its peak based on the emission profile data to ask the user whether to discontinue capturing images of the specimen.

10. The method of claim 1 wherein different weights are assigned to different frames of the series of non-destructive read images based on the emission profile data.

11. The method of claim 1 , further comprising:
capturing images of the specimen at a high frame rate using the non-destructive read operations; and
averaging frames captured at the end of the period of time to reduce read noise.

12. The method of claim 1 further comprising averaging or applying curve fitting methods of each signal read out from the image sensor as a function of time to estimate an amount of signal present to increase sensitivity of the image sensor in the digital imaging device.

13. The method of claim 1 further comprising:
calculating intensity of each signal read out from the image sensor based on location of the signal in the array of pixels, wherein a time profile of each signal is location dependent;
averaging each signal as a function of time to estimate an amount of signal present; and
shifting locations of the averaged signals to a same time instance as if each of the signals at each location started simultaneously.

14. The method of claim 1 wherein the reaction is a chemiluminscence reaction, a fluorescence reaction, or an absorbance reaction.

15. The method of claim 1 further comprising:
measuring a first time profile of the light emitted from the specimen using the non-destructive read images;
measuring a second time profile of a background region close to one or more bands of interest in the captured images; and
discriminating the light emitted from the specimen from the background of the images using a temporal difference between the first and second time profiles to discriminate the signals read out from the image sensor from unwanted background noise.

16. The method of claim 1 further comprising:
utilizing black pixels in a background region in proximity to a band of interest in the captured images to measure dark current noise for each exposure; and
eliminating local offsets and gain variations arising from temperature variations based on the dark current noise measurements.

17. The method of claim 16 further comprising improving fixed pattern dark noise reduction within the captured images based on the dark current noise measurements.

18. A digital imaging device for capturing digital images of a specimen in a chemical reaction comprising:
a processor;
a memory coupled with the processor via an interconnect bus;
an image sensor comprising an array of pixels for capturing a series of short exposures of light emissions from the specimen over a period of time during the reaction, wherein captured images of the specimen grow dynamically over the period of time as the number of exposures increases,
wherein the image sensor is configured to perform continuous non-destructive read operations to read out a set of signals representing non-destructive read images of the specimen from the array of pixels, and wherein reading out the signals is delayed until the end of the period of time to reduce read noise in the set of non-destructive read images,
and wherein the digital imaging device is configured to store in a memory of the digital imaging device emission profile data of multiple different assays including information relating to when an emission for a particular assay will begin rapidly declining; and
a monitoring module configured to continuously monitor the signals read out from the image sensor and discontinue capturing images of the specimen either automatically based at least in part on the emission profile of the particular assay in which the chemical reaction occurs, or based on input from a user of the digital imaging device.

19. The digital imaging device of claim 18 further comprising a graphical display configured to display the captured images of the specimen.

20. A method of capturing digital images of a specimen in a chemical reaction comprising:
capturing, by an imaging device, a series of short exposures of light emissions from the specimen over a period of time during the reaction, wherein captured images of the specimen grow dynamically over the period of

Assignees

• Bio Rad Laboratories

Inventors

• Swihart Steve
• Thrush Evan
• Ran Boaz

Classifications

• H04N25/581

  acquired simultaneously · CPC title

• G01N21/76 Primary

  Chemiluminescence; Bioluminescence · CPC title

• H04N23/73

  by influencing the exposure time · CPC title

• H04N25/67

  applied to fixed-pattern noise, e.g. non-uniformity of response · CPC title

• H04N23/741 Primary

  by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors · CPC title