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1、,Multiple and High-Throughput Droplet Reactions via Combination of Microsampling Technique and Microfluidic Chip,Members: 李娜 冯双霞 徐秋燕 刘婷婷 聂怀军,Contents,Background,Experiment,ABSTRACT,Discussion,ABSTRACT,Microdroplets oer unique compartments for accommodating a large number of chemical and biological r
2、eactions in tiny volume with precise control. A major concern in droplet-based microuidics is the diculty to address droplets individually and achieve high throughput at the same time.,Here, we have combined an improved cartridge sampling technique with a microuidic chip to perform droplet screening
3、s and aggressive reaction with reagent consumption. Our combined device provides a simple model to utilize multiple droplets for various reactions with low reagent consumption and high throughput.,Background,A large number of reactions can be independently miniaturized into tiny droplets ranging fro
4、m nanoliter to picoliter sizes without having to increase the chip size and complexity.,Microfluidic chips have provided a powerful platform for accomplishing droplet formation and manipulation within one chip of only a few square centimeters in size.,Advantages,Over the past few years, droplet-base
5、d microuidics has attracted increasing attention.,Background,Droplet generation for multiple samples is limited by the “world-to-chip” interface problem and cannot be addressed individually,Droplet generation and manipulation functions within one chip can easily interfere with each other and are dif
6、ficult To balance, despite being separated by a long, winding channel.,Drawback,Passive droplet formation methods:,Innovate,This context shows a hybrid device :the cartridge droplet generation technique combined with a microfluidic chip. They improved the cartridge technique with a novel movement sc
7、heme: the capillary, instead of the multiwell plate,was moved by a digital and automatic manipulator to aspirate different samples or the covering oil.,The hybrid droplet device for generation and manipulation consists of four major components . (a) manipulator (b)multiwell plate (c) capillary (d) P
8、DMS chip,Three general steps,load the multiwell plate with different samples, cover with a layer of oil, and input the parameters of the desired droplet array into the controller via a PC,start the controller to aspirate certain volumes of samples and oil into the Capillary sequentially,introduce th
9、e generated droplets into the PDMS chip for merging, mixing, detection, or other manipulation.,Laboratory reagent,silicone oil , FeCl24H2O (SigmaAldrich), FeCl36H2O (Acros Organics), ammonium hydroxide solution (28% NH3 Fluka), and hydrochloric acid (37% HCl, Acros Organics),Improved Sampling Techni
10、que,Combined Droplet Device Performance,High-Throughput Droplet Screening,Aggressive Droplet Reaction,Improved Sampling Technique,The capillary aspirates the oil when the cantilever remains in the “ up” state. When the cantilever is triggered to stay in the “down ” state, the capillary aspirates the
11、 sample. The residence time in the oil ( TO ) and sample (TS ) could be adjusted respectively to generate droplets with desired distance and volume.,(c) Relative intensity was measured along the channel starting from top right corner. The intensity of fluorescein and DI water droplet does not decrea
12、se or increase, which indicates that no cross- contamination between these two samples was detected.,(b) Droplet array was generated by sequentially aspirating 50 uM fluorescein and DI water.,Combined Droplet Device Performance,Here, the merging of droplets was demonstrated in a PDMS chip. The dropl
13、ets fusion does not depend on droplet distance but droplet velocity and Vd/Vc. After mixing completely, the merged droplet was output to a sinuous channel for display and detection.,In the rst application, a series of Ai and Bm,n ( i =1 2, m =1 3, and n=1 6) were generated. A1and A 2 are Fluo-4 and
14、Rhod-2 solutions with the same concentration (10.8 M), which are indicators that exhibit an increase in uorescence (green/red)upon metal ion bonding. A value of m =1 3 represent metalsion solutions of LaIII,Yb III, and YIII, respectively, while n =1 6 are six dierent metal ion concentrations (0, 2.5
15、, 5, 10, 20, and40 M) of these solutions. The droplet array contains 72 1-nLdroplets,High-Throughput Droplet Screening,The 36 pairs of droplet reactions used 72 nL of solution and required 1.8 min to complete. Therefore, the reagent consumption for each measurement could be reduced to 1 nL per sampl
16、e, and the reaction throughput is 1200 h1, which can be much faster by increasing the ow velocity. The screening droplets could be stored in the PDMS chip after we stopped the vacuum.,Aggressive Droplet Reaction,From these images, we found that the coprecipitation is so fast that it immediately form
17、s particles when two droplets come into contact with each other. Moreover, in each volume ratio, the precipitation initiated by the fusion of two droplets did not block the microchannel at such high concentrations . Such exible, controllable and miniaturized reaction conditions are extremely suitabl
18、e for aggressive, fast, or even explosive reactions that generate precipitation or heat.,Discussion,The cartridge droplet generation method provides an efficient way for introducing different nanoliter droplets into the microfluidic chip. the microfluidic chip offers a platform for delicate manipula
19、tion such as merging.,This feature is valuable for reducing the reaction screening and optimization cost and time and is particularly useful for drug screening.,Compared with the other cartridge droplet generation, our design used a digital and automatic manipulator to move the capillary instead of
20、the multiwell plate.,Discussion,Subsequently, the covering oil was ingeniously used as a carrier uid (continuous-phase) to avoid evaporation and cross-contamination.,The droplet generation throughputs in our sampling device increased to 1 5 s per droplet, which is ecient and versatile for arbitrary,
21、 multiple, and high-throughput droplet generation and could be increased by increasing the ow velocity.,This improved cartridge technique and microuidic chip were integrated to make use of their respective advantages for performing response calibrations and aggressive reaction and screening multiple reaction conditions with minimal (nL) reagent consumption.,,Thank You !,2012.11.19,