Manipulation of microfluidic droplets
View Patent ↗The invention provides methods for assessing one or more predetermined characteristics or properties of a microfluidic droplet within a microfluidic channel, and regulating one or more fluid flow rates within that channel to selectively alter the predetermined microdroplet characteristic or property using a feedback control.
1. A method for measuring droplet frequency comprising the steps of:
a) flowing a plurality of droplets in a stream of immiscible fluid;
b) exposing the droplets to a plurality of pulses of illumination, wherein the pulses of illumination are separated by a first duration of time;
c) capturing an image of the droplets over the plurality of pulses of illumination, wherein the image comprises an exposure from each of the pulses of illumination; and
d) calculating a droplet frequency for the plurality of droplets from the captured image.
2. The method of claim 1 , wherein:
the first duration of time is shorter than a time period between the droplets.
3. The method of claim 1 , wherein
the step of calculating the droplet frequency comprises calculating a first fundamental frequency using a Fourier transformation calculation.
4. The method of claim 3 , further comprising the step of:
e) exposing the droplets to a plurality of second pulses of illumination, wherein the second pulses of illumination are separated by a second duration of time that is greater than the first duration of time;
f) capturing an image of the droplets over the plurality of second pulses of illumination, wherein the image comprises an exposure from each of the second pulses of illumination;
g) calculating a second fundamental frequency for the plurality of droplets using a Fourier transformation calculation; and
h) comparing an amplitude of the first fundamental frequency to an amplitude of the second fundamental frequency to identify a temporal frequency of the droplets.
5. The method of claim 4 , wherein:
repeating steps e)-g) a plurality of times with incremental increases in the duration of time, wherein the temporal frequency of step h) is identified by a comparison of each of the fundamental frequencies.
6. The method of claim 5 , wherein:
the temporal frequency is calculated using a Fourier transformation calculation.
7. The method of claim 5 , wherein:
the duration of time is incrementally increased to a point where the plurality of droplets in a first image are not present in a second image.
8. The method of claim 1 , wherein:
the time period between droplets is associated with a spacing distance between droplets and a rate of the flow of the immiscible fluid.
9. The method of claim 1 , wherein:
the time period between droplets corresponds to the time between arrival of the droplets at a detector.
10. The method of claim 1 , wherein:
the pulses of illumination are provided by an LED source.
11. The method of claim 1 , wherein:
the droplets comprise an aqueous fluid.
12. The method of claim 1 , wherein:
the immiscible fluid comprises an oil.
13. The method of claim 12 , wherein:
the oil comprises a fluorinated oil.
14. The method of claim 1 , wherein:
calculating a droplet volume value from the droplet frequency.
15. The method of claim 14 , further comprising the step of adjusting droplet volume using a droplet volume value.
16. The method of claim 1 , wherein:
calculating a droplet count value from the droplet frequency.
17. The method of claim 1 , wherein:
the droplets are flowed in a channel of a microfluidic device.
18. The method of claim 1 , wherein:
the image is captured by a detector.
19. The method of claim 18 , wherein:
the detector comprises a camera.
20. The method of claim 18 , wherein:
the detector comprises a linear sensor array.