Saturday, March 31, 2007

Today I researched how to connect to the internet via my phone by looking at the (ITP's) mobile ubiquitous computing class' website. I was successful in gettinga text message sent through my phone, to my gmail account, and back to my phone, via php and perl.

I also tested sending current down different conductive threads to affect color change in my thermochromic ink, designed to change color at body temp or above. Threads with higher resistance work best, and I have placed an order for Bekaert VN 14 1/90 thread. It has a resistivity of 70 ohms/meter. Also, the thread is quite thin, almost like regular thread, so I may be able to use a sewing machine (I hope so!)


before power!

after power!

How to safely power this is still a problem, however. The easiest, yet obviously least desirable way, is to short a battery out while heating the thread. This naturally occurs when you respectively place either ends of the thread you are trying to heat, on the power and negative terminals of a battery; there are no components along the circuit using up all the voltage. It's basically a direct connection from the negative end of the battery terminal to the positive. Sparks fly and smoke wafts... something which is a bit disconcerting.

Thursday, March 29, 2007

On getting power to the threads:

So there are two ways of getting heat (created from putting power...) down the threads:

- short-circuiting the battery either end of the threads are attached to
- using peltier junctions or some other heating element

So far, sending current down the wire seems to work well. but there are sparks generated when power is connected! kind of scary..

On thermochromic inks:

There are a few different kinds of thermochromic ink out there. From cti inks, aside from being able to buy different colors, there are also inks designed to respond at different temperatures.

I've found that inks which turn color at body temperature work best when working with conductive threads.

I will try mixing the thermochromic ink with regular speedball screen inks. The idea is to get the thermochromic ink to turn to a different color when they are heated. There are a couple colors available from cti inks, which turn from one color to another, but I didn't like the color combinations they had available. Otherwise, the inks turn from their original color (the cold color), to clear. By mixing in regular screen inks (which will change the thermochromic ink's cold color, so don't forget your color theory), you can create a mixture that goes from one color when cold, to another after heated. When the thermochromic ink turns clear, you will be left with the original regular screen ink color.

I'm going to be using black thermochromic ink, so I won't have to deal with my cold color being changed (since black will mask whatever regular ink i add in). I want to go from black to pink, black to orange, or black to blue. Or maybe all three! We'll see.

I give thanks to Mouna for her advice so far, and have also been digging through Joey Berzowska's pages on working with thermochromic inks.

Thursday, March 22, 2007

Project kick-off

This project is going to be a culmination of many interests I've had all year long: thermochromic inks, mobile computing, and bluetooth technology.

Specifically, I am going to design a display system for a dress (which is pre-made, at least for this iteration of the project), whose display is affected by network activity, monitored via a bluetooth connection to my cell phone. The idea is that the cell phone, which maintains constant connection to the net, executes a php script, retreives the data, and then returns it to my garment, which controls the thermochromic display via an arduino.

For those who don't know, thermochromic ink is what Hypercolor was, back in the late 80s (remember those days??). It's ink that changes color with application of heat. Using resistance heating, enough heat is generated from a thread that has current sent down it, to change the color of ink designed to turn at temps above body temperature.

A flow chart, putting those words into a picture, can be seen here.

This is my initial outline for this project:

1. Draw flow diagram, showing how everything is connected

2. Data component
a. figure out how to connect to internet via bluetooth in phone
b. data scrape a site for test data

3. Physical component
a. sew conductive threads into a swatch with ink on it. test different threads for their effectiveness
b. set up circuit that lets me send current down different threads (maybe look at led array that leah buchley made?)

4. Visual component
a. figure out graphic design of print and what I actually want to do with it!
b. silkscreen graphic
c. sew in threads + circuit.