Heating Circuits and Thermochromic Experiments












Being inspired by two of the workshops we followed during summer camp : screen Printing Dynamic surfaces and Screen Printing Circuits, we decided to join our skills as a group to explore different ways to create a heating circuit which could be used to activate and control Thermochromic or liquid crystal inks.

The result of this three day project is a set of experiments with different kind of smart materials (conductive inks, nichrome wire, etc….) mixed with traditional textile technics like screen printing , knitting, crochet, hand painting, etc….


1_ Material : Conductive Copper Ink (CuPro coat paint from LESSEMF)



It works pretty well! We’ve tested it with Liquid crystal ink, 31°C Magenta and 37°C Purple Thermochromic ink.

See the diagram below :









Some results :








Most of our experiments were hand painted on non woven or very tight cotton weave.

We quickly realised that it was really difficult to get a very regular application of the ink with this process. If the application is irregular, some parts of the circuit will be more heated than others when connected and you won’t have an even colour change with your thermochromics. (See Pictures below)


Experiment 1






Thus, I reckon to use screen printing to apply the ink onto the bottom layer as this process allows to create a more even surface of ink onto the substrate. Several layers would need to be printed to be effective from 3 to 4 layers, depending on the conductivity you want to have, the screen you are using and the substrate you are printing on.


2_ Material : Nichrome Wire (Mindset Online.co.uk)

Nichrome wire, also called resistance heating allow, is made out of 80% Nickel and 20% chromium. When connected to a current from 0.3 mAmps, it begins to produce heat. Due to its characteristics and stability at high temperature it is commonly used in electric heating elements (Heated car seats for ex.)


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See the diagram below :













It appears to be a good and effective solution for heating. However, its wire form is preventing us from creating more complex designs and bigger heated surfaces than lines.