Team:Cambridge/Protocols/Flow coating

Flow Coating

Producing thin films using a blade.

Theory

The solution to be used is placed below the blade of the flow coater. The solvent evaporates as the blade is translated horizontally to leave a thin film over an underlying substrate.

Practice

1. Affix the substrate to the platform of the flow coater using tape.
   • Optional: In our runs we used scotch tape to affix a silicon wafer which served doubly as a height marker as it is known to possess a very uniform thickness. We then placed our silicon wafer behind this 'marker' wafer to allow for coating over the entire substrate.
2. Adjust the blade height to required height or to the height of the tape
3. Set the desired speed of forward motion and manoeuvre blade to edge of substrate
4. Load desired solution evenly underneath the length of the blade.
5. Activate blade allowing it to run the whole length of the substrate then stop the blade
6. Reverse blade and remove substrate, there should be a layer of thin film.

Notes: Although neat and implementable without access to fancy machinery with only a razor blade. In our experience this method is less reliable and requires finer tuning of speeds than spin coating. However it has been found this method can produce colour gradient films not just uniform colours unlike spin coating.

Safety

• The flow coater is generally very safe however it is important to avoid trapping loose pieces of clothing like ties sleeves etc. underneath the blade.
• All work was undertaken within the fume hood as we were working with a hazardous solvent.
• All work was carried out under technical supervision of Dr Matthew Hawkeye

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