Team:Cambridge/Protocols/Flow coating

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Revision as of 18:52, 29 August 2011

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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

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.
Adjust the blade height to required height or to the height of the tape
Set the desired speed of forward motion and manoeuvre blade to edge of substrate
Load desired solution evenly underneath the length of the blade.
Activate blade allowing it to run the whole length of the substrate then stop the blade
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

@@ Line 3: / Line 3: @@
 ==Flow Coating==
-How to make use of a flow coater in order to produce thin films.
+Producing thin films using a blade.
 ===Theory===
-The flow coater uses a blade which can be translated horizontally across a substrate in order to spread a thin film of a solution over a substrate
+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===
-Step 1 - prepare the substrate, affixing with scotch tape as this is known to have a very uniform thickness. This tape was initially used to set the blade height over the substrate. In future runs we used an blank substrate and scotch tape to set the blade height so that the actual substrate did not need to be fixed, thus avoiding the tape residue on the silicon wafer.
+# 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.
-Step 2 adjust the blade height to the height of the tape or some other item of known thickness.
+# Adjust the blade height to required height or to the height of the tape
+# Set the desired speed of forward motion and manoeuvre blade to edge of substrate
-Step 3 Drop your solution in the center at the end nearest the flow coater blade.
+# Load desired solution evenly underneath the length of the blade.
+# Activate blade allowing it to run the whole length of the substrate then stop the blade
-Step 4 activate the forward motion of the blade, it is best to experiment with different speeds, low speed can be used to form a film of declining thickness, whilst a fast translation forward will result in a more uniform thin film.
+# Reverse blade and remove substrate, there should be a layer of thin film.
-Step 5 activate reverse motion and remove the substrate.
+'''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 very safe as it only moves a small distance, it was kept in the fume hood as we were using a hazardous solvent and to eliminate the risk of a chemical splash.
+* 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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