HOW TO GET WHAT YOU WANT

Soft Interactive Technology I

Nov 29,30,Dec 4,9,2018 10:00- 17:00 elab Weissensee Art Academy Berlin.

Materials

Highly conductive textile materials
Copper Ripstop Fabric Shieldex Kassel
Company: Statex
Characteristics: Corrosion proof copper-silver plated polyamide ripstop fabric, < 0.03 Ohms/cm2 surface resistivity.

Shieldex Technik-tex
Company: Statex
Characteristics: Silver plated knitted fabric, 78% Polyamide + 22% Elastomer plated with 99% pure silver, < 2 Ohms/cm2 surface resistivity (front/visible side). stretchy in one direction

High Flex 3981 7X1
company: Karl Grimm
Characteristic: Very conductive, Solder-able

Shieldex Shieldex 235/34
company: Statex
Characteristic: Shieldex 235/34 dtex 4-ply HC: Silver plated, 50 Ω/m ± 10 Ω/m

Elitex Fadenmaterial Art Nr. 235/34 PA/Ag
company: Imbut GmbH
Characteristic: silver conductive thread (100% polyamid beschichtet mit silber
Elitex_Fadenmaterial

Materials: Resistive (not so conductive) textile materials
Eeonyx non woven carbon resistive
Company: Eeonyx
Characteristics: Resistive material (2k), non woven, can be used to make pressure or bend sensor

Eeonyx stretch woven carbon resistive
Company: Eeonyx
Characteristics: Resistive material (2k), knit/ jersey, Stretch in both direction. Can be used to make pressure or stretch sensor

velostat
Company : 3M
We bought it from lessEMF, but 3M produces it and there are more retailers.
Characteristics: Piezo resistive. Changes its resistance when pressed. Good for pressure sensors.

Nm10/3 conductive yarn
Company: plug and wear
Characteristics: Nm10/3 conductive yarn, 80% polyester 20% stainless steel, light grey, Surface resistance < 100000ohm

conductive wool
Company: Bekaert
Characteristic: Wool fiber mixed with stainless steel fiber, Suitable for felting

Multimeter

We can not see the electrons flowing. So we can not tell by looking if there is an electrical connection, or how much electrical resistance between one end to the other end of the circuit or a material.
To measure this, we use a tool called multimeter. This will be your friend throughout the workshop. Here is how to use it.

Check connection

turn the dial to arrow/sound sign. Place the probe to the to end of the part where you want to check the electrical connection. If there are connection, it will beep.

Check Resistance

Turn the dial to ohm mark part. there are few numbers on the ohm part, start from the smallest, or if you know roughly how much it should be, start with closest one. If it is on the diral 200 ohm, it means it will measure the resistance maximum 200ohm. If the resistance is bigger than 200ohm, it shows 1. like in the picture. In this case, turn the dial to bigger maximum range (for example 2000, or 20k (20,000)) to see if you start to see a number.

Here is an example on how to read the measured resistance. The dial is set to 20M ohm (20,000,000 ohm), and you see 2.19 in the display. Where the period is shows the scale (if it is Mega or Kilo or without any scale). Since you are on Mega scale, this is 2.19 Mega Ohm (2,190,000 ohm). This is a bit confusing as if you are on 200k ohm dial and see 3.8, it is still 3.8 Kilo ohm (3,800 ohm). The number on your dial is not a multiplier. It just shows which scale you are in, and what is the maximum reading range.

Textile Sensors

Push Button

http://www.kobakant.at/DIY/?p=48

Tilt Switch

http://www.kobakant.at/DIY/?p=201

stroke sensor

http://www.kobakant.at/DIY/?p=792

Button Switch

http://www.kobakant.at/DIY/?p=7349

knit stretch sensor
http://www.kobakant.at/DIY/?p=2108

Bend Sensor
http://www.kobakant.at/DIY/?p=20

pressure sensor for heavy weight
http://www.kobakant.at/DIY/?p=5689

Stretch Sensor

Conductive Wool: Needle felt Squeeze Sensor
You can mix a bit of wool to increase the range of resistance change.

eeonyx non-woven: Slider/ potentiometer

http://www.kobakant.at/DIY/?p=543
http://www.kobakant.at/DIY/?p=2331

Adjustable Slider
photos >> https://www.flickr.com/photos/plusea/albums/72157685063387786
>> http://www.kobakant.at/DIY/?p=6886

Voltage Divider

If you have 2 exactly same resistors, the voltage gets half in the middle, like the first diagram. As the ratio between two resisters changes, the voltage you get in the middle (between the resisters) changes accordingly.
One can calculate this by
Supply voltage (5v) x resistanceA / (resistanceA + resistanceB) = divided voltage

So much of a theory, let’s try this to see if it really works. Here is an experiment with two resister with a multumeter.
The first experiment shows two same size resister (10kohm) dividing the provided voltage (5V) in half. The multimeter is set as V– for reading direct current voltage. The probes are connected to 0V (GND) of the power supply and the middle point where two resisters meet. You can see 2.44 in the multilmeter’s display. (almost 2.5V.. maybe the resister had some range) It divides the 5V in 50/50 ratio.

In the second experiment, I changed one of the resister to 47kohm. So now the ratio of two resisters are 10/47. So, I should read 5V x 10/(10+47) = 0.877 V in theory. As you can see in multimeter, it is 0.85V it measures. Not bad!

Now, if you change one of the resister to our resistive textile sensor, it works the same. The felt sensor I tested here has about 8kohm – 100kohm resistance range. You can see how the voltage that gets divided in the middle changes as I manipulate the felt. Now, if you connect the point where multimeter is reading to the arduino Analog input, we can read how much voltage comes in.

Reading Sensor with Arduino

In this course we used Arduino and its IDE to read sensors we made. You can download IDE from here >> https://www.arduino.cc/en/Main/Software

Once you get your Arduino connected, we did an exercise with Blink example >> https://www.arduino.cc/en/Tutorial/Blink

Then you can connect Analog sensor you have made with above circuit connection. You can upload AnalogReadSerial example >> https://www.arduino.cc/en/Tutorial/AnalogReadSerial and read how your sensor is behaving.

When you are reading digital sensor(contact switch), then you can simply replace the sensor from above circuit to your digital sensor and move the reading pin from Analog Input Pins to Digital Pins. Make sure in your setup function to set the PinMode of your reading pin to INPUT.
If your fixed resistor on your voltage divider is too small (less than 1k ohm) it may not work as your digital sensor’s internal resistance can be high. In this case, switch your fixed resistor to something bigger (1k or bigger) and it should work.

Reference Tutorial:
https://www.arduino.cc/reference/en/language/structure/control-structure/if/
https://www.arduino.cc/reference/en/language/functions/math/map/
https://www.arduino.cc/reference/en/language/functions/math/constrain/
https://www.arduino.cc/en/Tutorial/PWM
https://www.arduino.cc/en/Tutorial/TonePitchFollower?from=Tutorial.Tone2
https://www.arduino.cc/en/Tutorial/ToneMelody?from=Tutorial.Tone

The last thing we tried is Capacitive sensor.
Here is the tutorial to Capacitive sensor >> https://playground.arduino.cc/Main/CapacitiveSensor?from=Main.CapSense

Assignment

The next 2 days will be something like mini hackathon. It is time for you to explore what these textile sensors can do as interface and think about different types of interaction with digital technology. For this, we give ourselves a framework/story.

Inspired by “Desert Island”, a BBC radio show, the theme of our hackathon is following.

Pick one “app” or function from your phone or computer that you would take if you were to be cast away to outer space, to a desert planet.
– Why did you choose this app?
– Analyze how you normally control/interface this app.
– Imagine how you would use this app if you were in space/desert planet
*We assume all the infrastructure to use the app (internet, GPS.. so on) is functioning exactly same as on earth so we can focus on interaction part.

For example, I can choose Map. I use this often in my everyday life, and I think it can be handy if I am on Moon or Mars exploring the terrain.
My interaction analysis are following:
– input name of a place or an address, sometimes get direction to there (typing, active interaction)
– Check where I am and my orientation (GPS, compass sensor, passive interaction)
– zoom in/ out of the map (multi finger touch, active)
– I am visually looking at the map (display)
– I hear voice navigation to my destination (display)

Now I can plan new sets of interaction for my space excursion and decide which of them will be implemented with e-texitile sensors.

The 2 days can be spent to explore what kind of sensor construction will achieve the interaction you planned, what kind of materiality, aesthetic is possible for your design, how it can be integrated in garment and iterate your design.

Many of the way we use our digital devices are influenced by the design of the device. So if you are designing a new device, you can also design new ways to interact with the digital device. Here are very nice critical analysis of how we came to get used to some of the strange interaction we perform with our digital devices. (see the book)
Curious Rituals >> http://curiousrituals.nearfuturelaboratory.com/#introduction