Droplet generation method, system and application
Disclosed are a droplet generation method, system and application thereof. The method breaks through the limitation that the existing nanoliter scale droplet generation technology must use micro-channels below 0.1 mm, and can realize the preparation of small-volume uniform droplets at a reduced cost. The system includes a droplet generation device and a droplet receiver, the droplet generation device includes an accommodating cavity with a variable volume, a control mechanism for controlling the volume of the accommodating cavity to change periodically, and a droplet generation tube, which has a wide range of applications in clinical diagnosis, gene expression analysis, microorganism detection and other fields.
1 . A droplet generation method, using a droplet generation device and a droplet receiver, wherein, a first liquid is placed in the droplet receiver, the droplet generation device comprises a fluid passage, an accommodating cavity having a volume which is variable and in liquid communication with the fluid passage, and a droplet generation tube having a first port and a second port, wherein the first port is in liquid communication with the accommodating cavity, an inner diameter of the second port is greater than 0.2 mm; wherein the droplet generation method comprises:
S1, transferring a second liquid into the droplet generation tube, wherein the second liquid is a liquid immiscible with the first liquid;
S2, inserting the droplet generation tube into the first liquid, and keeping the second port of the droplet generation tube being below the a liquid surface of the first liquid; and
S3, while having the droplet generation tube and the droplet receiver remain stationary with respect to each other, controlling the volume of the accommodating cavity by subjecting the accommodating cavity to a periodic change while simultaneously injecting a driving fluid into the fluid passage to drive the second liquid to move, thereby generating droplets of the second liquid;
wherein at least a part of a wall constituting the accommodating cavity is a movable part, a vibration mechanism is connected with the movable part, to subject the periodic change by making the movable part vibrate;
wherein the periodic change is a compression-recovery reciprocating change, or an expansion-recovery reciprocating change, or a compression-recovery-expansion-recovery reciprocating change.
2 . The droplet generation method according to claim 1 , wherein, in step S3, droplets are formed in the droplet generation tube, and then flow out through the second port and enter the droplet receiver.
3 . The droplet generation method according to claim 1 , wherein, in step S3, the generated droplets are formed in the droplet generation tube, and then flow out through the second port and enter the droplet receiver.
4 . The droplet generation method according to claim 1 , wherein a frequency of the periodic change is 10 Hz to 1 KHz.
5 . The droplet generation method according to claim 4 , wherein, the frequency of the periodic change is 100 Hz to 600 Hz.
6 . The droplet generation method according to claim 1 , wherein the movable part is composed of a metal or non-metal diaphragm; and/or, one or more of a top or the surrounding side walls of the accommodating cavity are provided with the movable part.
7 . The droplet generation method according to claim 1 , wherein the movable part is connected with the vibration mechanism through a connecting mechanism, and in step S3, the vibration mechanism drives the movable part to vibrate reciprocally and synchronously to control the volume of the accommodating cavity to change periodically.
8 . The droplet generation method according to claim 7 , wherein a direction of the reciprocating vibration of the vibrating mechanism is vertical direction; and
a vibration amplitude is 5 μm to 1000 μm.
9 . The droplet generation method according to claim 1 , wherein the droplet generation method comprises a step of cleaning of the accommodating cavity and the droplet generation tube after step S3 or before step S3.
10 . The droplet generation method according to claim 9 , a first plunger pump is used in the step of cleaning, and a second plunger pump is used in the step of injecting the driving fluid into the fluid passage in S3, the first plunger pump has a volume larger than a volume of the second plunger pump, and the fluid passage is connected to the first plunger pump and the second plunger pump through a three-way valve.
11 . The droplet generation method according to claim 1 , wherein an inner diameter of the first port is larger than the inner diameter of the second port.
12 . The droplet generation method according to claim 1 , wherein the inner diameter of the second port is 0.2 mm to 1 mm.
13 . The droplet generation method according to claim 1 , wherein the inner diameter of the second port is 0.3 mm to 0.6 mm.
14 . The droplet generation method according to claim 1 , wherein a frequency of the periodic change is 150 Hz to 300 Hz.
15 . The droplet generation method according to claim 1 , wherein a vibrating mechanism is set abutted against the movable part, and in step S3, the vibrating mechanism transmits a reciprocating vibration to the movable part to make the movable part vibrate, so as to control the volume of the accommodating cavity to change periodically.
16 . The droplet generation method according to claim 1 , wherein the droplet generation tube comprises a tapered tube portion, and two ends of the tapered tube portion respectively form the first port and the second port; and
a taper angle of the tapered tube portion is 0.05 to 0.1, a vibration frequency of the movable part is 100 Hz to 600 Hz, and a vibration amplitude is 10 μm to 300 μm; or
a taper angle of the tapered tube portion is 0.1 to 0.2, a vibration frequency of the movable part is 100 to 300 Hz, and a vibration amplitude is 10 μm to 600 μm.
17 . The droplet generation method according to claim 1 , wherein in step S3, the driving fluid is a liquid and has an injection speed of 2 to 200 μL/min.
18 . The droplet generation method according to claim 1 , wherein the accommodating cavity is an annular cavity with an inner diameter of 4 to 6 mm, and an inner peripheral side wall of the accommodating cavity extends in a vertical direction.
19 . The droplet generation method according to claim 1 , wherein in step S1, the second liquid is sucked into the droplet generation tube through the second port of the droplet generation tube, which is followed or not followed by sucking a portion of first liquid into the droplet generation tube;
before step S3, the driving fluid and the second liquid are located in the droplet generation tube in sequence from top to bottom; or, the driving fluid, the second liquid and the portion of first liquid are located in the droplet generation tube in sequence from top to bottom.
20 . The droplet generation method according to claim 1 , wherein the first liquid contains a surfactant, the second liquid is an aqueous phase containing biological or chemical substances to be detected, a diameter of the droplets is 50 μm to 250 μm.