20.109(F07): ECD assembly

Protocol

Part 1: Phage titers for M13.1 and MDS

Record the number of plaques for each plate you prepared last time, and then use the most "countable" to calculate PFU/ml for the M13K07/M13.1 and WT/MDS pairs. To collect the class's data in one place, you should then copy two tables to the data collection page. Since we might want to publish this class data in a peer reviewed journal, it will be particularly important for you to provide complete and accurate information as well as for you to "sign" your work so we can attribute you properly.

Plaque numbers

	phage = M13K07, strain = MG1655	phage = M13K07, strain = MDS	phage = M13.1, strain = MG1655	phage = M13.1, strain = MDS
10-6
10-8
10-10

Titer

	phage = M13K07, strain = MG1655	phage = M13K07, strain = MDS	phage = M13.1, strain = MG1655	phage = M13.1, strain = MDS
titer (PFU/ml)

Part 2: Li overlay

1. Examine your dried pattern. If there are any patches of IrO2 nanowires deposited on the non-ITO part (i.e. the part that was etched away during the acid wash), you can carefully remove them using a cotton-tipped applicator that is damp with methanol. Be very careful as you do this because you could easily ruin your pattern.
2. Place both slides into a 50°C oven for at least 20 minutes to fully evaporate any water that is on them. (Not crucial for 20.109 lab.)
3. Before you begin mixing the electrolyte solution, you’ll need to clean a 20 mL scintillation vial. To do this you’ll want to blow out any dust that is in the vial with house air or nitrogen (or a high pressure air bottle).
4. Begin making polymer electrolyte solution by dissolving 1 g of electrolyte salt into 7.5 g of solvent in your 20 mL scintillation vial. It may be difficult the dissolve the salt. To speed up the process, put a small magnetic stir bar into the vial. Put the vial onto a stirring/heating plate and heat the solution while stirring until the salt is fully dissolved. Once it is fully dissolved, turn off the heat.
5. Add 1.5 g of the monomer solution to the solution from the previous step and stir until mixed.
6. To make the initiator solution, add 70 mg of the initiator to 1 g of the solvent in a 2 mL microfuge tube. Vortex until fully mixed. Spin the tube in a microcentrifuge and add the solution to the monomer/electrolyte solution. Mix fully by vortexing or by spinning on spin plate. The initiator is light sensitive, so try to move quickly. Once the solution is fully mixed, wrap the entire vial in tin foil to protect it from light.
7. Remove the plastic covers from the silicon septum. Carefully lay the septum on the ITO side of the patterned slide so that your pattern is fully enclosed by the septum. Note that the septum is larger than the pattern and that some of the unpatterned portion of your slide also will be enclosed by the septum. If you’d like to get really fancy, you can trim the septum down so that you end up with a square of septum that is exactly the size of your pattern (this is not necessary, though).
8. Make sure that the septum is fully sealed to the slide at all points, so that nothing can leak out between the septum and the slide.
9. Open the vial with the monomer electrolyte solution. Using a 1 mL micropipette, add ~700 uL of the solution to the space on top of the slide that is surrounded by the silicon septum. Add this solution slowly and try to evenly disperse it across the slide. Do not allow any bubbles to form. Do not worry about completely covering the slide – when you add the second slide to the top it should spread out the polymer solution.
10. Put the second ITO slide (ITO side facing the septum) onto the patterned slide / silicon septum stack. When you add it, make sure that the overhanging end (the end not covered by the septum) is not on the same side of the slide as the overhanging end from the patterned slide (see figure). We will need to hook up both slides to different electrodes and if the two overhanging ends are facing each other, it will be very difficult to do this.
11. Carefully wipe off any of the polymer electrolyte that has leaked out of the sandwich.
12. Place the ECD sandwich into a plastic Petri dish. Next to the sandwich put a small dab of the polymer solution (you can use this dab to check for solidification of the polymer). Place the Petri dish onto a UV irradiation box for at least 10 minutes. This will activate the initiator and the polymer solution will form a solid gel. NOTE: NEVER EXPOSE YOUR EYES OR SKIN TO THE UV LIGHT.
13. Gently test to make sure that the polymer solution has hardened. If it has, then remove the ECD from the UV irradiation box and use some epoxy to seal the edges of the device. Try to seal all of the septum / slide connections. Place the sealed device into a 50°C oven for 5-10 minutes until the epoxy has cured.
14. Remove the ECD from the oven. It is now finished and ready for testing!
15. If you’d like, you can clean the glass surfaces of your device with a cotton applicator that is damp with methanol. You can also try to use a razor blade to trim any excess epoxy. Be careful as you do this, because the slides can crack if you use too much force.
16. You can test the ECD by hooking up your battery box to it. Use the alligator clips to hook the positive electrode to one end and the negative electrode to the other end.
    1. IrO2 film hooked to positive = oxidation = removing Li+ from IrO2 film = absorbs light = appears dark
    2. IrO2 film hooked to negative = reduction = pulling Li+ onto IrO2 film = clear

For next time

1. titer?, summary paragraph
2. summary of ECD, variables and effects
3. final presentation directions