Droplet generator chips offer a lot of possibilities how to use them and to optimize the results. Besides the structure itself, the operation mode matters. Sample inlet and main stream channel might be varied, a hydrophobic surface coating may be applied, or simple variation of the flow velocity or the injection volume can be modified, resulting in different droplet patterns. The following description aims to give an idea how to start with such devices followed by a set of further experiments.
Hints to work with droplet generator:
Droplet generator chip 0162
1. Droplet generator chip, material PC (polycarbonate), (13-1002-0162-03)
2. Handling frame, e.g. orange (15-4001-0000-12)
3. Male Mini Luer fluid connectors, e.g. the green version (09-0541-0331-09)
4. Male Mini Luer fluid connectors, e.g. the opaque version (09-0538-0331-09)
5. Male Mini Luer plugs, e.g. the red version (09-0551-0334-09)
6. Silicone tube, e.g. ID: 0.5 mm (09-0802-0000-00)
7. PTFE tube, e.g. ID: 0.5 mm (09-0803-0000-00)
8. Oil, e.g. 20-5004-0000-00
9. T-piece for tubing
10. Fluorescence dye
11. Peristaltic pump
12. Tube for peristaltic pump
13. Two channel syringe pump or two syringe pumps
14. Eppendorf vessel
Step 1: Chip & handling frame
1. Insert the chip in a handling frame
Step 2: Interface chip & pump for aqueous phase
2. Connect the central entrance for the aqueous phase via an opaque Mini Luer connector, a silicone sleeve, a PTFE tube, the pump tube and a further PTFE to the pump containing the aqueous phase (e.g. sample with dyed).
Step 3: Interface chip & pump for oil phase
3. Connect the ports for the oil phase via green Mini Luer connectors, silicone sleeves, PTFE tube, the splitting T-piece, the pump tube and a further PTFE to the pump containing the oil phase.
Step 4: Close redundant exit ports
4. Plug all unused entrance ports and exit ports of the chip with Mini Luer plugs besides the central exit port.
Step 5: Interface chip & collection vessel
5. Connect the exit port via a Mini Luer connector, a silicone sleeve, and a PTFE tube to the Eppendorf waste reservoir
Step 6 – 7: Carry out experiment
6. Start pumping the oil and wait for a stable flow.
7. Start pumping the aqueous phase and observe droplet generation. You have to eventually vary the flow rate of the aqueous phase to generate droplets of the desired size.
Step 8: Visualisation of the experiments
8. Visualize the experiment with a fluorescence microscope and characterize the droplet size.