液滴微流體是個可以對微粒進行混和、分選的高通量平台。液低分選可分離目標微粒並研究其行為，並可應用於藥物篩選。當含有多顆細胞或不含細胞的液滴需被包覆進入微珠時，精準的作動以及自動分選就顯得至關重要。因此，我們設計出一個微流裝置，可以精準的對單一顆微粒進行包覆並可快速的進行分選。
這篇論文中，我們設計出一個帶有三維電極的微流體裝置，以用於高通量液珠分選。使用狄恩流(Dean Flow)以弧狀流道及依慣性排序對單顆細胞進行包覆以產出液珠。液珠分選分為兩個階段，包含將液株收集進軟管以及將液珠注入電場之中。
第一個晶片在控制液珠大小的情況之下，有80%可對單一細胞或是微珠進行包覆，這些液珠會被收集進入鐵氟龍管中。第二個晶片則可產生電場，讓不同的液珠如PBS液珠、蔗糖液珠及含有微珠或是細胞的液珠產生偏移，最終被推送到不同的位置。
以20千赫茲/200伏特產生之電場致使PBS液珠偏移，當流速為2.6 µl/min時，液珠距管壁 260 µm，最大液珠偏移為61.19 µm ; 當流速為3.6 µl/min時，液珠距離管壁180 µm，最大液珠偏移為49.22 µm。以蔗糖製成的液珠部分，
當流速為2.6 µl/min時，其在Y軸向上的偏移量為 180 µm，最大液珠偏移為11.24 µm ; 當流速為3.6 µl/min時，液珠距管壁 172.12 µm。實驗結果證實此裝置確實可以分選不同的液珠。並在低包覆失敗的狀態下，成功的以液珠包覆單顆細胞並進行分選。實驗結果證明了此包含液珠收集及在注入功能之裝置的有效性。

Droplet microfluidics is a high-throughput platform with ease of sorting, merging and compartmentalizing of micro particles. Droplet sorting provides us a platform to isolate and study behavior of the target particles for applications like drug screening. In droplet microfluidics precise manipulation and self-sorting of droplets has been a key issue along with large number of empty and multi-cell droplets when encapsulated with micro particles like cells/bead. Hence, we developed a microfluidic device with precise droplet manipulation of only one micro particle encapsulation and rapid sorting of droplets.
In this thesis, we present a microfluidic device with three dimensional electrodes on it for high-throughput spontaneous sorting of droplets. Curved micro-channels with inertial ordering of particles i.e. Dean Flow aids for single cell encapsulation with the precise match of periodicity of the cell flow with the droplet generation. The sorting of varied population of droplets is achieved in two stages i.e. droplets collection in flexible tubes and droplets re-injection in the dense electric field. The first chip encapsulated exactly one cell/bead in droplets with high probability rate of 80% along with control on size of droplets and collection of droplets in a long circular Teflon tube, while the second chip generated dense electric field and deflected different populations of droplets like PBS droplets, sucrose droplets and droplets with cells/beads to different y positions. The maximum deviation of PBS droplets obtained is 61.19 µm at the flow rate of 2.6 µl/min and 49.22 µm at the flow rate of 3.5 µl/min for a frequency of 20Khz. Post deflection the maximum deflection y-positions of PBS droplets obtained is 260 µm at the flow rate of 2.6 µl/min and 180 µm at the flow rate of 3.6 µl/min. The maximum deviation of sucrose droplets obtained is 11.24 µm at the flow rate of 2.6 µl/min and the maximum deflected y-position is 172.12 µm at the flow rate of 3.6 µl/min for a frequency of 20Khz. Experiment results confirmed potential of the device to sort variety of droplets. Successful encapsulation of injected cell sample into droplets with exactly one cell, with minimal number of empty droplets, and sorting is demonstrated. The experimental results indicated the efficacy of this sorting device using droplet collection and re-injection method.

Abstract i.
Content ii
List of Figures iv
List of Tables vii
Chapter 1. Introduction 1
1.1 Background 1
1.2 Motivation 2
Chapter 2. Literature Review 4
2.1 Droplet Formation 5
2.1.1 T- junction 5
2.1.2 Flow Focusing 6
2.2 Sorting 7
2.2.1 Geometric 7
2.2.2 Magnetic 9
2.2.3 Dielectrophoretic 10
2.3 Three dimensional Electrode………………………......................12
2.3.1 Fluidic Electrode 11
2.3.2 Gel Electrode 12
Chapter 3. Theory of Dielectrophoresis 14
Chapter 4. Chip Design 16
4.1 Chip…………………………………………………………………..19
4.1.1 Dean flow 17
4.1.2 Different designs for droplet generation……………..........18
4.2 Sheath focusing …………………………………………………….21
4.3 Electrdoe design…………………………………………………….22
Chapter 5. Fabrication 24
5.1 Standard Lithography 25
5.1.1 Cleaning 27
5.1.2 Spin-coating 27
5.1.3 Pre-baking 27
5.1.4 Exposing 28
5.1.5 Post-baking 29
5.1.6 Development of Alignment Mark 29
5.1.7 Development 29
5.1.8 Post-exposing 29
5.2 Soft Lithography 30
5.3 PDMS Membrane 31
5.3.1 Spin Perforation30 32
5.4 Oxygen Plasma Bonding 33
5.5 Three-dimensional electrode 34
Chapter 6. Simulation Results 35
6.1 CM Factor 36
6.2 Electric Field 37

Chapter 7. Experiment Results and Discussion 43
7.1 Droplet Science.
7.1.1 Dean focusing and droplet formation 43.
7.1.2 Droplet formation and patterns…………………………….45
7.1.3 Droplet collection and techniques………………………….46
7.1.4 Droplet re-injection and sheath focussing…………………49
7.1.5 Conductivity tests…………………………………………….51
7.1.5 Cell culture and morphology……………………………….53
7.2 Sorting experiments and electric field………………………...53
7.2.1 Droplets deviation and analysis……………………………..55
7.2.2 Comparison of deviation lysis……………………………….65
7.2.3 Discussion..…………………………………………….…….66
7.3 Image Processing 65.
7.3.1 MTrack 2 66.
Chapter 8. Conclusion and Future Work 70.
8.1 Conclusion 70.
8.2 Future work 71.
Reference 72

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