Studio Contrechoc

design & textile & technology entries

Linking the 2015 Swatch

After the knitting of the swatch, two sides had to be linked on a circular linker. It saved time to attach 4 or 5 swatches at the same time. So the swatches are draped around the linker.


After linking two sides, one side remained open for inserting the magic. One layer of plastic and one layer of paper, — both insulators — with aluminum foil at the back connected to a rectifier bridge can make a LED flash when you knock on the two layers.


The two layers had to be inserted into the swatch. The polyesther threads will help the tribo electric effect a little bit (hopefully :-).

After inserting the 30 double layers the second linking closed the swatch. A bit of caring for some stray wires and the production is finished.


Knitting the 2015 Swatch

At the coming e-textile summercamp the Swatches will be exchanged. The Swatch is a sample of small size showing some aspect of a combination of textiles and electronics. A group of e-textile designers willing to put a lot of work into this exchange all make 30 samples and these samples will be distributed at our meeting in Paillard, France.

Making a prototype is easy. Normally there are 3 – 5 versions necessary to have a finalized version which is presentable. But than making 30 copies is another business. You have to organize all the needed components (most of the time you have “some”, but not 30 and then find the same things like the knitting yarn, or the same conductive thread is sometimes even impossible!).

And e-textile designers are experimenters, so we like to change and always look for possible improvements. So making 30 identical copies is … stress!

In my production time there are three phases: the first phase is slow, because I really have to start the production, make it a bit “faster”, modular, more efficient. Then all stages are getting into my system and production is started. But in the last phase I have to be careful to stay concentrated, I get careless start thinking of other projects, and am likely to make stupid mistakes.

My swatch, after making the first prototype, is now divided into three production events:

knitting: knitting the envelop

electronics: making the tribo electric “battery” and connecting the rectifier bridge and the LED

linking: putting knitting and electronics together and close the envelop by linking.

These three production phases ask for different types of concentration. With the knitting the knitting machine – laptop combination must be working impeccably. I had a problem with the board (lobotomy of the KH-940). What was wrong with the board? In the end, after checking all the connections of this fragile board, it was the USB cable! Replacing the cable solved all connection problems. Who doubts his USB cable???? In this knitting phase eventually during production I make all possible mistakes. Forgetting the weights, reversing the cast of order, breaking threads, etc, etc, etc. With machine knitting you can make a lot of mistakes indeed!

The electronics are reduced, but still this can go wrong: in my first sample after linking the knitting (closing the envelop) a wire got detached. Good for the production: make sure the wires are very very very well connected, because the knitting will not facilitate soldering inside!

The linking can be done by hand, but as a hand stitcher it would take me another week…so a linker machine is used. Of course arriving at this linker at school it is out of production. First I had to repair it. But then things go smooth.


The 30 copies knitted, not linked yet.

Description of this swatch can be found here:

All coming swatches can be seen here:

E-textile summercamp 2015:


Knitted at the KH-940

Screen Shot 2015-07-05 at 08.16.49

Knitting Pattern, for lace knit.

Victory over the Sun: Paillard 2015 version

This blog post serves as the documentation for the work on display at Paillard 2015.

vos1 vs1


Energy Harvesting, game


Victory over the Sun is a dress which makes it possible to compare the use of several ways of generating energy. In this version the energy of a solar cell can be compared to the energy generated by rotating a hand crank. The amounts of energy for each source is played out to each other on this wearable. Varying circumstances, inside outside, shade, sun gives different results. Playing this game with this wearable is apropriate because it is easily displaced  in different situations, sun, shadow, twilight etc


By playing the gameit becomes clear that it takes a lot of effort to generate an amount of energy to load the supercap, that the sun generates this energy effortlessly when it shines optimally on the solar cell, but that this solar cell is not always (most of the times not at all) in optimal placement when you run around in this dress.


The material used for this dress is pieces of worn out jeans which are still usable. This recycling of material fits the project concept of harvesting energy, that is using energy which is self generated or “left over”. In theory this using worn out material seems nice, but in practice worn out really means the fabric is weak even if you don’t notice it directly. It can be seen at several places that the fabric is very fragile.


For the course of this energy game two verticals rows of bright LED’s are visible at the front of the dress. These lines of LED’s have a double indication. The main indication will an lit LED at the scale of the energy generated, the higher in the row the more energy, the second is another LED which uses the whole scale to indicate progress.

The second expressive behavior occurs after the game, in the discharging mode. The back light up in red and white and these colors fade gradually depending on the discharging rate.



Left to right: hand crank, supercaps, ATtiny85’s, LTC3105

The energy of the Sun is generated by a solar cell. For the hand crank is used a hacked Ljusa of IKEA. The energy of both sources is stored into two seperated 10F supercaps. Two ATtiny85 monitor the voltage in these supercaps. If the voltage in the supercaps stayes above the 5V a winning indication is flashed over the LED’s.

Then the energy is released. The first idea was using an LTC3105 energy harvesting chip to store the energy back into the lipo, charging the lipo.

The second idea was to use the bright Ljusa LED’s inside the back of the silhouet, so creating “a second” expressive behavior.

vs2   vs3

Presentation mode:

For the Paillard exhibition a special presentation mode is made. The electronics has got its own small shade lamps, and the front LED’s will be lit, simulating a game. After the simulated game the back will be lit as if the supercaps discharge.

Artistic Result:

Victory over the Sun is an artistic research result of a Design & Energy harvesting investigation:

Other presentations:

Victory over the Sun was displayed at the Hochschule für Künste in Bremen in 2015.

Victory over the Sun will also be presented at the Willem de Kooning Academy in Rotterdam in octobre 2015.

Former posts about this project:

First and Second sketch version:

Teensy 3.0, BlueSMiRF and Mindwave

In the last post the Serial and SoftWareSerial of the Arduino and Coolterm and the UART of the BlueSMiRF were performing some acrobatics, but it is all possible.


After buying a Teensy LC and Teensy 3.0 this acrobatics was made much more simpler using the possibilities of combining USBSerial and Serial1. On the Teensy 3 Serial Ports are available.

With the Teensy the BlueSMiRF is connected to a Serial Port and the data can be seen in a Serial Window:

Screen Shot 2015-05-12 at 09.02.17

And because this project involves servo motors, it is nice the Teensy has so many PWM Pins and Timers!

The basic Arduino BlueSMiRF test script can be found here:

You can find how to configure the BlueSMiRF for connecting to the Mindwave here:—hacking-mindwave-mobile

The Teensy page on Serial UART:




Bluetooth boards and the Neurosky Mindwave

For some project the Mindwave Neurosky with bluetooth was interesting. Jostie quickly made an Android App, which could connect to the Mindwave during the 2015 NASA App Challenge weekend in our neural network attempt:


His app can be found here:

bt9 From Mindflex, with Serial to Mindwave Mobile with bluetooth

But we wanted the signals directly available for a wearable. For this a bluetooth board was needed, which could connect to the Mindwave. Several options were available.

By studying two tutorials constraints for this setup are becoming clear:

  • The board has to have the possiblity to behave as a master, connecting to the Mindwave.
  • The communication has to be Serial (that is fast) and not SoftWareSerial (two reasons for this!)


We tried different boards (although we could have guessed that only the boards mentioned in the tutorials would function 🙂 —stubborn!—

bt3  older BT board, old – hard – school – command coding RX-TX connection

Easy Bluetooth ( not for sale anymore?)
This is an “older” board, from a few years ago. No problem connecting and using as a slave. There is more: In this pdf of 100 pages you can see that you can enter the command mode, and make this board a master. But … this is the real stuff in command BT-coding, will cost some time to study.

bt5 see the wires: SPI connection: 6 besides the V and GND

Bluefruit LE – Bluetooth Low Energy (BLE 4.0) – nRF8001 Breakout (

A recent board. Communicating easily with an app, sending to a wearable. This board is easy to connect to, but functions as a slave. So for our purpose this board cannot be used. Besides, compared to the other boards, the SPI connection has a lot of wires…

The documentation from Nordic is also extensive:…/2981/…/nRF8001_PS_v1.3.pdf .

bt4 very nice, “designed” connection at the FTDI of this RF12 board

Bluefruit EZ-Link – Bluetooth Serial Link & Arduino Programmer – v1.3 (

This is a board with some nice possibilities as can be discovered here:

It can be connected to the FTDI header of a Jeenode, making the Jeenode having both the RF12 and bluetooth wirless.

The board has an optional JST connection. So you can make a standalone module witha lipo attached. Only problem: the lipo in the JST connector is always on: no on-off switch. So in practice this connector requires soldering a switch in the wiring to the lipo, which is not fun.

But as can be read in the FAQ of Adafruit:
Can EZ-Link act as a BT ‘master’?
No, it is a client-mode only device.

End of story for our purposes.

bt1 without the BEE carrier, programming with the AVR SPI mkII

Bluetooth Bee – Standalone ( )

This board has a bluetooth part combined with a ATmega168P (Not an ATmega168 as told in the wiki).

The wiki can be found here:

Getting this board working did cost more time. Using an AVR ISP mkII programmer (not the X Bee carrier) was the first hurdle. After a while the J1 connector functioned – or the configuration was understood.. Uploading code was possible after adding the ATmega168P code to the Arduino boards.txt file, using the shift-U command in the Arduino environment.

Screen Shot 2015-05-07 at 09.54.15 Screen Shot 2015-05-07 at 09.55.27

(Our AVR ISP mkII is hacked so that it provides either 5V or 3.3V directly to the board – this one needs 3.3V.)

The LED’s (red-blue) on the BT board code as follows (no the description in the wiki): Master mode: double fast blue: not connected, single blue: connected. Waiting to pair: red, blue alternating.

If paired right from the laptop you get a BT – Serial link in the Arduino environment. Opening this as a serial monitor initiates the pairing, the key “0000” is given automatically. The board is in slave mode. The example code worked, the led could be lit and “shut”.

Screen Shot 2015-05-07 at 09.55.02

But the master mode is needed.

At this page about the Bluetooth Bee you can find the commands :

The code used to get the master mode using the commands can be in the scripts at github:

The communication is done using SoftwareSerial. On this board communication is hard wired using pin’s 2 and 3. See the schematics at:

This hard wired connection is the problem for our project. For the Mindwave to give signales regularly a faster connection is needed than the SoftWareSerial can provide—the “normal” Serial connection on pin 0,1 is much faster—, as will be seen in the last bluetooth board which is tried out. The signales are coming through with SoftWareSerial, but apparently there are so many bits falling out that sometimes you have to wait seconds or even 10’s of seconds for new values of the Mindwave.

The script using this Bee Standalone board can be found here: (mind the baudrate which is set at 57600, default 38400 – start using this value to set the baudrate at 57600). It functions, the LED signals received values from the Mindwave, but not too often and at irregular intervals.

The second problem for our project is also related to using SoftwareSerial. We want to transfer the values from the Mindwave to servomotors. But the Servo lib and the SoftWareSerial lib are incompatible (probably they use the same timer).

So also this board is not what we needed.

Nice post in Japanese:,

bt2 nice and clean, connected to an ATmega328 board with RF12

 BlueSMiRF Silver (

This board was mentioned in both the relevant tutorials. So no wonder that this board functions. Using the command mode it can be programmed in Master mode and the MAC address of the Mindwave can be entered. Connection and reconnection is done automatically.

In our project we spent time using the SoftWareSerial instead of the Serial port, with the intention of debugging. The speed difference resulted in dataloss (apparently) and only some packages of the Mindwave were received in minutes. With the Serial, pin 0,1, Mindwave values enter once or even twice a second.

SoftWareSerial was used to communicate with Coolterm (or other Serial monitor) to see what was happening and debugging. This interfered with the servo motor lib.

The ATmega328 board (Jeenode) with the RF12 provided a solution: bluetooth signals from the Mindwave are received using the UART of the Smirf, then the signals can be transmitted using the RF12 transceiver. These signals can be received in a similar board.

Scripts using the Mindwave and this board can be found at:

The projects with these boards and scripts will be presentated later…


Bremen King’s day presentation

Five projects were presented at Bremen, Hochschule für Künste, during the Dutch celebration of King’s Day, 28 April (Bremen date of this day). We did this presentation of e-textile projects together with 5 projects of (which can be found there).

The dummies with the projects were placed in the middle of the people attending the celebration. The wearables were blending in so well, that there interactivity could be conisdered as “normal”. Also, because of this interactivity on these puppets, the normal clothing the visitors were wearing could easily be imagined interactive. The future of garments and clothing is near, because it cannot be considered “alien” anymore.


Overview, Solar Rim Dress, Victory over the Sun, Social Wind, Je Suis, Supernova t-shirt


Solar Rim Dress



Social Wind


Supernova t-shirt in the “Geburtstaggeschenkvortrag” at Galerie Am Schwarzen Meer, Bremen.


Small Talk Timer in action



Social Wind together with the Spine Warming Dress and the Solar Fiber project of


Back of “Je suis”



Front of “Je suis”


About Interfaces of wearables

Designing a wearable has many aspects. The fabric shape and the functioning are the first concerns. After these parts are solved other things which doesn’t seem important are added.

Within the interface part a division can be made between the expressive part and the interaction part: the expressivity can be movement (Je Suis, Social Wind), some sort of light information (Solar Rim, Change Partners, Supernova shirt), etc. About this expressivity see this post:

The interaction part is about switching the wearable on and off, charging or changing the batteries.

This last part of the interafce is one of the tricky aspects of every wearable.

Interfaces of the last sort for wearables are tricky because at first it is outside the scope of the design. The on/off switch is added when the project is finished. You have to figure out the most convenient spot on the wearable. It “main switch” also has to be a spot which can be found but also is hidden in the sense that it not obvious. This means you have to solve a paradox.

Then the wearable can have different modes. For instance the normal functioning mode, where a laptop sends data wireless to the wearable for display, and a presentation mode with programmed data without the laptop.

To study possibilities, difficulties etc a list of wearables and interfaces/modes:

Project modes interface
Social Wind, ventilator module normal mode (temperature/humidity sensor), display mode switch, button
Solar Rim dress normal mode, display mode 1: one month of data, display mode 2: block data around the circle of 64 LED’s, display mode 3: epicycle mode. textile switches at sleeves, snap fasteners
Victory over the Sun one normal  game mode switch
Je Suis one normal mode – distance sensor, extra button for activation by hand switch, button
Supernova Shirt and trousers one normal mode switch
Change Partners / Talking Timer one normal mode, interaction soft button switch, conductive patches

Pictures of interfaces:

int2 Victory over the Sun, switch. Hidden

int7  Solar Rim Dress, soft buttons, left mode options, right snap fastener-  switch. Visible

int6Je suis module, back side, switch and button (right top, near motor). Visible

int5 Social Wind, Ventilator Module, switch. Hidden

int4 Social Wind, Led panel module, switch. Hidden

int3 Change Partners, Talking timer, switch.  Hidden

First conclusion:

If the electronics is designed separate from the wearable shape, the switch ends up hidden, on the electronics board. Hidden switches are difficult to find, even for the designer, after a few months.

So, the switch should be part of the wearable design, see the snap fastener design of Solar Rim.


If the switch is part of the fabric design then the electronics gets entangled with the fabric. This has two related disadvantages: testing gets more complicated because you cannot test the electronics without the wearable, and recycling that is separation after use gets more difficult.

The solution could be to add one switch to the electronic design and connect this switch to a second switch in the fabric. After integrating the electronic switch is switched on, and having the material switch in series this last switch will be used after all is assembled.

Victory over the Sun: technical testing

The dress described in former posts was finished finally.

The dress as a result of an artistic research into energy harvesting and design is presenting a game situation. By rotating a dynamo you have to compete with the Sun and a solar panel in generating energy. The game is created in a wearable so that you can change to another location. Playing the game in different locations makes you aware of the power of the Sun’s energy in comparison to your own muscle energy.

The dress is very much a prototype. As can be seen from the electronics a large amount of testing is needed to make some sort of a playable game.

The electronics was fitted inside 4 acrylic casings:


dynamo charger, supercaps/lipo, the brains: 2 ATtiny85’s and bitshifters, and an LTC3105 energy harvesting chip.

then fitted to the side of the dress: (which makes us aware that we should have thought of a better wiring 🙂


Up left: the charging dynamo, up right, the ATtiny85’s, and the bit shifters, down left, the supercaps, and lipo, then bottom right, the LTC3105 for recharging the discharged energy into the lipo.

After fitting the casings will be covered with small pieces of jeans, only the dynamo charger will be visible.


Two out of the three casings covered.

The choice for 2 ATtiny85’s was made from the first version where we had only 4 LED’s for the two sources of energy. But now after making it all we realized that the 2 ATtiny85 with the bit shifters should have been replaced by one ATmega328, with a LED-block script, avoiding the bit shifters. This would have saved one casing. This will be done in the next (third) version of the electronics.


Besides the solar panel a battery pack is installed to make testing in a room without the Sun easier, you can test by switching to battery pack (right side, next to the solar panel). The wiring between all the casings and groups of electronics is done by female – male connectors. This makes testing easier.


The second version of the script discharged the supercaps after winning. Winning is reaching the 5V mark. But what about starting a new game after abandoning a game half way? It was decided to discharge the supercaps at the start, when you switch on. Discharging is not what is seems. Following the voltage of the supercaps to about 0V, you see the voltage rise again without any charging. So discharging is now done in steps, then some delay, then measure the voltage again, if it is above a limit, discharge another round and so on.

This repeated discharging worked…until the dress was put in the full sun. The solar panel is generating so much energy that the discharging is not fully obtained. The discharging time had to be made bigger.

The installed solar panel is doing 0.1V a second so it will win in 50 seconds if the Sun is not hindered by clouds. At the moment it is practically impossible to win this using this hand crank dynamo hacked from the Ljusa.

Besides that, as could have been expected 🙂 the big LED’s are not visibly on or off in the full Sun. Another interface should be added, or these LED’s like this removed and giving it a try with small superbright LED’s.

A movie of the solar panel racing towards the 5V:

After observing the problem of the LED’s not visibly lit in sunlight, we tested bright LED’s in a simple script at 3V:

So the big 10mm LED’s will be replaced by these 3mm bright LED’s.

Interactive top

Fot the presentation in Bremen we made a simple interactive piece for a possible fundraising auction.

The piece is made of five sided regular shapes. The fabric is lasercutted and the pattern of the the bigger form is coming back in the middle of the shape as a pattern.

From 6 regular five sided shapes a top is constructed in a way we did for 10 years in painting. The difference is that the fabric folds itself around the body, being different from 2D tessalation.

p1 Screen Shot 2015-04-19 at 10.12.19

(see more paintings here:

One of the fabric shapes and some of the paintings in the same configuration as used for the top. Added are two basic shapes one to the right and one to left side. In painting this would have meant that the 2D plane was abandoned. For the textile top this means we get a spatial form slightly coming outwards.

Pattern of the top:

Screen Shot 2015-04-19 at 11.34.05

A picture of a model (Jasna Rokegem) wearing the top:


For interactivite we added three LED’s in the middle of the sides of the central shape. These LED’s are soft glowing, faster or slower depending on the value read by a light sensor exactly at the middle of the protruding shape(LDR).

The nice thing about this top is that you can even hang it on the wall and enjoy its abstract reflections without wearing it yourself 🙂

The script is fairly simple and can be found here:
version 1: glowing led’s:
version 2 (meant for the back): led’s shwoing light variations:
Both scripts can also be found at github:

Needed: ATtiny85, three LED’s, 1 resistor of 2K, 1 LDR, coin cell battery holder, 3V coin cell battery.

Victory over the Sun version 1.0, design and energy considerations

Second version of the Victory over the Sun project.

After the sketch version (see post the recycled jeans dress is totally modified. The front is reordered in horitontal strips, where the big LED’s form two curved lines. These 8 LED’s plus one at the bottom will  report about the game between the solar cell and the dynamo which is operated and powered by your hand and arm.


The back side is decorated with a pattern using the laser cutter.

vic3 backside

The material is recycled jeans. The idea is that there should be a match between the concept of energy generating and the material that is recycled. The jeans were worn for a few years and the worn out parts were removed. From the left over parts, which seemed still ok the dress was assembled. But in handling the fabric it was noted that also the seemingly good parts were deteriorating fast. In total contrast with the energy of course. Energy is energy, even if it is transformed many times. There is no comparison between fabric and energy, although we humans tend to associate green, “nice” energy with green recycling of goods and fabrics. Our tender ideas are not appreciated by reality.

The electronics is improved after the first skethc version. The LED’s are extended to 8. In the dress there are 9 LED’s. The two bottom ones will be used to indicate that a game is going on.


Inside of the dress, connecting the LED’s. The parts of the electronics, LED’s, circuitry, supercaps are all connected using connectors, so that testing is made easier.

In the electronics the supercap of 1.0 for each of the participants was replaced by two supercap’s of 10F at 2.5V in series. Now a player has to work to get to 5V!

One problem remained and remains. After the game a lot of energy is stored in the supercaps of 10F at 5.0V. You can calculate this energy: the formula is Energy of a capacitor = .5*C*V*V.

See for instance:

This means 125 J. In the first version this was only 12.5J because the Cap was 1.0F instead of 10F.

After the game this energy has to be dissipated to start a new game. But this getting rid of the energy costs time. The first try was using a ventilator. Even a cooling ven for a computer running normally at 12V could be used and took minutes to get the voltage of the supercaps down.

vic5 The ven is visible at the left bottom.

The last experiment was to charge the lipo used for the circuitry of the game.

During dissipation the voltage of the supercaps drops from 5.0V to hopefully 0V. The lipo battery is between 4.1V and 3.6V. So to charge the lipo a special LTC chip is needed (LTC3105) , to keep the voltage at 4.2V during charging back the energy of the game into the lipo. This LTC is actually a harvesting chip studied during a research on energy harvesting:

So the supercap should be connected to this chip and the output of the chip fed back into the lipo.


Expected was a fairly normal exponential behavior while discharging. Not quite so!

This is a typical graph of the Voltage over the supercap and the charging current to the lipo:

Screen Shot 2015-04-06 at 19.55.27

The time axis is not linear, noted were values of tens of mA of current and the corresponding remaining Voltage over supercaps. The LTC3588 took care of keeping the charging voltage to the lipo n 4.5V, even till the supercaps were at 1.5V.

There is a spike in the middle of the graph which was reproduced.

The drop-off is not exponential, probably because the charge pump is being cleverly regulated, this LTC 3588 chip is fairly complex.

The discharging is made interesting, but the last problem remains: the charge on the supercaps will not be brought back to 0V, which is the ideal starting point for the game. On the other hand with the 10F caps, the game takes long enough for the human arm to get tired. So maybe we keep this way of discharging.

One might get anxious about the lipo. If the lipo is charged to quick, things may get nasty. But the voltage of the lipo changed during charging only 1mV, from 3.81 to 3.82. The energy density of the lipo is far more bigger than the supercaps:

Lipo battery of 1400mAh * 3.8V = 3600 * 1.4 * 3.8 =~ 19000 J. So the 120 of the supercap does not really impress the lipo.

Adding an oscilloscope picture:


Yellow line: voltage over the supercap,

Blue line: inverted voltage over a shunt of .5 Ohm. For a square this means 10 mA. Maximum current 24mA. The current is different from the former graph because of the shunt

Start: first 4.9V being above the voltage fed to the lipo 4.2V (so the chip DC-DC downwards), then you see the crossing of this set voltage, the chip has to DC-DC upwards to 4.2V, there is a discontinuity, the current delivered is bigger -more efficent? After that the exponential. The last part is still interesting, the chip really keeps the voltage up to 4.2V while the supercaps ar at 1.5V.