7th Oct 2007

The next step for my project is to design another circuit that would be able to control LED patch. In the mean time, me and Soon are discussing what to test out for the thermochromic ink. There are two options we are thinking of doing - silkprint pattern on shirt, or dying to make flower accessory that attach to the shirt; together with the LED, we can have three user tests.

We had a lot of problems with the thermochromic ink and conductive yarns:
1. Heat distribute to the unthreaded area is very slow. It is always the threaded area first change very fast to white without seeing any gradient change. This is because the conductive yarn we bought has high resistivity, so for a fixed total resistance limited by the power, we can only use a shorter length, and hence for the same area, we will have to sew with a wider spacing.

2. Yarn would show on the front
comparison of using nichrome wire and conductive yarns

Front:
23820362.397a0b.jpg

Back:
23820351.3ae205.jpg

3. The heat distribution too slow, while the area in contact change very fast that there is no gradient in color change. Hard to achieve multiple color

4. For the ones that self-printed, after color changing, it will not go back to original color anymore. I guessed this may be due to the wrong drying process.

Based on our problems, me and Soon wanted to have some testing plans. So we will test with different dying and silkprint method with proper or non-proper drying process. Then we will need to find out what is the optimum spacing of the yarns.

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