by Matti Niinimäki & Emmi Pouta
[We are still hoping to get some better images or video from somewhere]
Opodiphthera Incognita is a dress that changes its color and shape when the user feels threatened. It is not meant to be an actual method of self-defense, but more of a conceptual garment that plays with the idea of shape shifting and primal reactions.
Using Flexinol Wire
Flexinol wire – or muscle wire – is wire that contracts or goes back to a certain shape when it is heated. This effect can be used to create controllable linear motion by heating the wire with electricity. The muscle wire we used was Flexinol 0.010″ diameter high temperature wire from Robotshop. It needs to be heated to 90 °C to activate it.
The wire required about 1 A of current to contract. This meant that we had to use approximately 60 cm long pieces of the wire with our 11.1 V Li-Po battery.
We had a lot of problems trying to figure out the best way to attach the flexinol wire to actually get decent movement with textiles. Paper was much easier since it holds its shape better and can be guided to move in certain way by folding it.
In the end, a zig-zag pattern with tight stitches in the ends and loose stitches in between seemed to be the best way to do it. Although, we weren’t totally happy with that either and only managed to get two small moving pieces for the final dress.
Using Thermochomic Pigments
Usually, thermochromic inks are painted or printed straight to the textile surface, but we wanted to try something different. We painted some red silk yarn with the thermochromic pigment and then used the yarn to weave our own textiles. Black thermochromic pigment was mixed with some silk screen paste to create the ink. The black pigment did not actually come out as black when mixed with the red color of the yarn, but more of a darker red or purple. This turned out to be a nice accident since the dark red was quite beautiful.
We experimented with different kinds of weaving patterns.
We also wove some resistance wire into the fabric that was used as the heating element to change the color. We used resistance wire since we did not have the proper conductive thread with small enough resistance rating.
In the final dress, we had three color-changing strips of fabric with four loops of resistance wire embedded in them. Each length of resistance wire drew roughly 600 mA so in total the color-changing part of the dress drew about 2.4 amps. The total current consumption of the entire dress peaked at about 3.5 amps, so we weren’t really comfortable having anyone actually wearing the dress just in case something had gone wrong.
Muu Gallery Presentation
We had some bad luck when transporting the dress to Muu Gallery and the connections to the resistance wires broke. It seemed to be impossible to solder the resistance wire and the connections were made with some crimp beads. That seemed to work at first, but they actually broke when we took the dress of the mannequin. We were able to fix some of the connections, but in the end, parts of the dress did not change color at the Muu Gallery.
We also did not have time to finish the hood so that it could be moved and used to trigger the movement and color change. We had it set on a timed loop instead.
In the end, we did not quite reach our ambitious goal, but the dress itself looked very beautiful and still changed color and moved slightly. The materials we picked were very challenging to use, but we learned a lot while trying to figure them out.