Temperature control on digital microfluidics device

1. A microfluidic device, comprising:

a first substrate structure having a first substrate surface;

a second substrate structure having a second substrate surface facing the first substrate surface and spaced apart from the first substrate surface to form multiple fluid channels for one or more droplets between the first substrate structure and the second substrate structure; and

a plurality of electrodes adjacent to the multiple fluid channels for moving the droplets by electrowetting;

wherein the multiple fluid channels comprise:

a first region including a first fluid channel for receiving a droplet;

a second region including a second fluid channel for receiving one or more reagents;

a third region in communication with the first region and the second region, the third region including a third fluid channel configured to mix the droplet with the one or more reagents to obtain a mixed droplet; and

a fourth region in communication with the third region, the fourth region including a fourth fluid channel configured to process the mixed droplet;

wherein the microfluidic device further comprises:

a first heating element and a second heating element disposed on either side, respectively, of the third region of the fluid channel; and

a third heating element and a fourth heating element disposed on either side, respectively, of the fourth region of the fluid channel.

2. The microfluidic device of claim 1 , wherein the microfluidic device is configured to perform droplet amplification in the fourth region.

3. A microfluidic device, comprising:

a first substrate structure having a first substrate surface;

a second substrate structure having a second substrate surface facing the first substrate surface and spaced apart from the first substrate surface to form multiple fluid channels for one or more droplets between the first substrate structure and the second substrate structure; and

a plurality of electrodes adjacent to the multiple fluid channels for moving the droplets by electrowetting;

wherein the multiple fluid channels comprise:

a first region including a first fluid channel for receiving a droplet;

a second region including a second fluid channel for receiving one or more reagents;

a third region in communication with the first region and the second region, the third region including a third fluid channel configured to mix the droplet with the one or more reagents to obtain a mixed droplet; and

a fourth region in communication with the third region, the fourth region including a fourth fluid channel configured to process the mixed droplet;

wherein the microfluidic device further comprises:

a first heating element and a second heating element disposed on either side, respectively, of the third region of the fluid channel;

a third heating element and a fourth heating element disposed on either side, respectively, of the fourth region of the fluid channel; and

wherein the fourth region comprises a plurality of hydrophilic surface regions spaced apart from one another by hydrophobic surface regions, the fourth region configured to process the mixed droplet such that a portion of the droplet forms a plurality of microdroplets on the hydrophilic surface regions when the droplet moves over the hydrophilic surface regions.

4. The microfluidic device of claim 1 , wherein the fourth region comprises a hydrophobic surface region and configured for droplet digital PCR (Polymerase Chain Reaction).

5. The microfluidic device of claim 1 ,

wherein the first substrate structure comprises a first base substrate and a first dielectric layer disposed over the first base substrate, with the first substrate surface overlying the first dielectric layer; and

wherein the plurality of electrodes are disposed in the first dielectric layer.

6. The microfluidic device of claim 1 , wherein the plurality of electrodes in the first substrate structure comprises a plurality of actuation electrodes; and

wherein the second substrate structure comprises a second base substrate and a common electrode.

7. The microfluidic device of claim 1 , further comprising one or more temperature sensors disposed on the first substrate surface.

8. The microfluidic device of claim 7 , wherein the each of the one or more temperature sensors comprises an NTC (native temperature coefficient) thermistor.

9. The microfluidic device of claim 1 , further comprising one or more temperature sensors disposed on the second substrate surface.

10. A microfluidic device, comprising:

a first substrate structure having a first substrate surface, the first substrate surface configured to receive a droplet, wherein the first substrate surface comprises a plurality of hydrophilic surface regions spaced apart from one another by hydrophobic surface regions, the first substrate surface configured to process the droplet such that a portion of the droplet forms a plurality of microdroplets on the hydrophilic surface regions when the droplet moves over the hydrophilic surface regions;

a plurality of electrodes disposed in the first substrate structure and configured to apply an electric field to the one or more droplets;

a second substrate structure having a second substrate surface facing the first substrate surface and spaced apart from the first substrate surface to form a fluid channel between the first substrate structure and the second substrate structure, at least a portion of the second substrate surface being hydrophobic;

and

one or more temperature sensors disposed adjacent to the fluid channel between the first substrate structure and the second substrate structure.

11. The microfluidic device of claim 10 , further comprising

a first heating element adjacent to the first substrate structure and disposed on an opposite side of the first substrate surface;

a second heating element adjacent to the second substrate structure and disposed on an opposite side of the second substrate surface

wherein:

the first heating element is a TEC (thermoelectric cooler) Peltier heater; and

the second heating element is a resistive heater.

12. The microfluidic device of claim 10 ,

wherein the first substrate structure comprises a first base substrate and a first dielectric layer disposed over the first base substrate, with the first substrate surface overlying the first dielectric layer; and

wherein the plurality of electrodes are disposed in the first dielectric layer.

13. The microfluidic device of claim 10 , wherein the plurality of electrodes in the first substrate structure comprises a plurality of actuation electrodes; and

wherein the second substrate structure comprises a second base substrate and a common electrode.

14. The microfluidic device of claim 10 , wherein the each of the one or more temperature sensors comprises an NTC (native temperature coefficient) thermistor.

15. The microfluidic device of claim 10 , further comprising one or more temperature sensors disposed on the second substrate surface in the space between the first substrate structure and the second substrate structure.

16. A method for controlling a microfluidic device, comprising:

providing a first substrate structure and a second substrate structure, the first substrate structure having a first substrate surface and the second substrate structure having a second substrate surface, the second substrate surface facing the first substrate surface and spaced apart from the first substrate surface by a distance to form a fluid channel for one or more droplets;

determining fluid channel temperature from one or more temperature sensors disposed on the first substrate surface; and

controlling the temperature of the fluid channel by:

controlling a first heating element disposed adjacent to the first substrate surface based on the fluid channel temperature in the fluid channel; and

controlling a second heating element disposed adjacent to the second substrate surface based on the fluid channel temperature in the fluid channel.

17. The method of claim 16 , wherein the each of the one or more temperature sensors comprises an NTC (native temperature coefficient) thermistor.

18. The method of claim 16 , wherein:

the first heating element is a TEC (thermoelectric cooler) Peltier heater; and

the second heating element is a resistive heater.

19. The method of claim 16 , wherein controlling the temperature of the fluid channel comprises:

controlling the first heating element to heat the fluid channel to a first temperature for a first time duration for droplet amplification;

controlling the first heating element to heat the fluid channel at a second temperature for a second time duration for droplet annealing; and

setting the second heating element at a preset third temperature.

20. The method of claim 16 , further comprising sensing temperature of the fluid channel using one or more temperature sensors disposed on the second substrate surface in the fluid channel.