(Update05) CA1

I always had second thoughts when I was doing the research for different type of colour changing material: How can they be applied on textile if they were not in form of screen printable dye?
Three main criteria to choose the material:
1. The material have non-emissive colour changing property, ideally, it should be able to appear multiple colours under different conditions;
2. The material need to be electrically controllable;
3. The material could be applied to texitle.
As a brief summary, current chromatic materials can be categarized according to different type of  stimuli:
 Material          Stimuli
 photochromic  UV light
 thermochromic  heat
 electrochromic  voltage
 solvatochromic solvent polarity
 Ionochromic  ions
 halochromic  PH
 Tribochromic mechanical friction
 piezochromic  pressure
Among all the chromatic materials, according to the 3 criteria mentioned above:
1. All of them have colour changing property. But currently only thermochromic Liquid crystal could switch multiple colour among red-blue-green-transparent. Reseach is being carried out by some chemistrists to see whether electrochromic material will also gain multiple colours with different event voltages.
2. We focus more on three types of more commonly used and available chromatic materials (photochromic, thermochromic, and electrochromic materials). Methods could be implemented to control these 3 materials:
- For photochromic, we thought of using optical fiber to generate UV light exposed to photochromic layer to control the colour change. However, this method only works when the wearer is indoor (with no exposure to external UV light). It will fail once the wearer goes into sunshine(outdoor). Thus the photochromic material will not work for our desire.
- For thermochromic material, the idea is that the material is applied on a heat generating layer. For example, resistor, conductive ink and conductive thread could be fit in this case. Experiments need to be carried out to see how this heat and cooling process could be realised. It is feasible, but will not be easily controllable as we imagine.
- For electrochromic material, we could adjust the voltage applied to the electrodes to control the displaying colour.
3. However, talking about feasibility, whatever material we choose in the end, we need to find a way to apply it on the textile. Otherwise it would be just an extra displaying layer. Current technology only offers photochromic ink and thermochromic leucodye ink that could be screen printed on textile. After being filtered by criterion 1 & 2, it seems that we could only use thermochromic leucodye ink, which also only allow colour change from transparent to one certain colour.

There are 3 ways we could carry on with our project:
1. Play with the property of thermochromic leucodye ink (alternate between transparent and one certain colour only) and conductive yarn, but focus more on the design of the textile to achieve multi-colour effect.
* Use matrix, fill each basic square with different colour.
** the square dye with same colour will appear simultaneously under electrical control
*** when the matrix is scaled down, we can obtain a visual effect of red or yellow fabric (as illustrated above)
**** Press http://tw.youtube.com/watch?v=f9JLx5JSADQ to view the VIDEO for vivid illustration.
2. Source for Liquid Crystal Ink (multi-colour change)

* as indicated by Fabcell,'This liquid crystal ink is made by mixing the liquid crystals made into microcapsule formulation with the synthetic resin. ' I am wondering whether this ink is commercially available or compounded in their lab (the first case stands higher chance)
* Anyway I have send request to IIC, inquiring about their LC ink:
 - whether it is textile applicable
 - what are the colours available and what are the event temperatures
 - quotation.
3. We could also look into the direction how to make electrochromic material to be textile printable ink. However, we can not pretended to be chemistrists.