Again, laser cut pvc seems to be a super star. This time the cuts are made bigger and the fabric strips are slimmer, which when laser cutted, they start to look like golden threads.

This time the outfit is intentionally made big and (a bit strange!). This is a festive outfit, that converts signal output to tones. Same as the previous post, with the same logic of the readings, the sensor here uses a GSM antenna so it triggered mainly by cellphone.

The idea initially was to embed the sensor in a tshirt, and integrate a fractal antenna as part of the tshirt’s laser-cut printed pattern, however, that was a bit challenging after I learned that the antenna, in this case, needs to be perpendicular to the ground plane (which is the body!), which was going to bit challenging with application and keeping it horizontal and stable. It was meant to convert data from RF to tones, and in this case you can simple wear your tshirt, plug your headphones to your ears, then start listening to the surrounding differently.

However, when things didnt work with the tshirt, things took a different path: Same as the item in the previous post, this one is also based on the planes generated from antenna filed volumes. The item is basically an oval plan, that could be reshaped and re-adapted based on how you fix its connections

The idea is to make it as festive as possible. I didnt yet have the chance to experience how it blends in a carnival in real live, but it blends well in urban context. The idea of having a GSM antenna, is that the sensor could be triggered by mobile. When a phone is close to the sensor, the reading increases, when you receive a call it increases more, the presence of more than one sensor around, makes it increase more, and so on..

Not but for a first iteration, however, as the prototype in the previous post, the sensor needs better integration with the wearable and a better use of making the interestingly looking pvc, more interactive.

I am testing how it looks like with the presence of interactive visualization around it, and will be posting how this went, soon.

This is a small post that tells you the story of making pvc garments for RF sensors.

PVC sheet are awesome. Flexible. Strong. Semitransparent, and cheap. Ideally, we are not supposed to laser cut them, but because fablabBCN is awesome, so we can.  Set the power to (15~20) and the speed to 75 on the Epilog laser and go ahead.   It should be fast and not so powerful otherwise the sheets are deformed or become very curled that you can’t work with them.

Those wearables’ shapes are inspired by plane surfaces generated from volumes created by antenna fields. Well, the field shapes change according to antenna design and frequency, but those prototypes are only inspired, it is not accurate or parametric, which is something that could be investigated in a further iteration.

Below is a step by step documentation on how the process takes place and how the material looks like through the different phases. The idea, initially was to make use of how interestingly the material diffuses the light, and use it to reflect the sensor readings, but the plan didn’t run exactly as imagined, at least, so far.

 Smelling burning PVC isn’t fun, so it better to keep away from the machine while working. The material itself keeps an unpleasant smell for a few days or a few hours, depending on the size. Don’t wash it or treat it, it just looses the smell gradually by itself.

The item, separately, is quite interesting, I guess and is appealing for guys and girls (Thanks to Blanca Duarte and Gerard Rubio for modelling!)


Now, lets see, how to integrate the sensor within. In the early stages of this project, I had trials for finding ways to make the lightest circuit possible, I tried conductive ink (which was incredibly impossible with smd components) and tried copper sheets, which was fine for most components, except for the very small RF log piece.

It gets really challenging trying to be creative while using smd components! So finally I gave up and decided to just mill a normal pcb board because the above ones didn’t work!
Then trying to go creative with the antenna, that was even more challenging:

For instance,this is a pcb milled fractal antenna, that didn’t mill correctly.
Weaved wires are incredibly attractive to work with..but
Performance wise,it just doesn’t work! I even tried weaving fractals, but that was completely insane! That wasn’t a bad trial using copper sticker on cardboard, but the thickness and the properties of the cardboard affects its performance, also not being rigid enough, doesn’t help.
So I just used normal 1.5mm laminated copper wire loop and biquad antennas, and they worked. It is challenging to combine creative crafting with antenna that needs considerations with orientations, ground connections, alignment..etc. I used online javascript calculators to get dimensions and specifications.

So initially the circuit was that big Then replacing the arduino with those cute attiny84 pieces: We end up in a much accommodate circuit which is rough on a prefboard, and demonstrates my horrific soldering talents, yet it works, just plug in 2 CR2032 3V batteries. I made a necklace that goes with the pvc piece above, the integration isn’t great, but .. Even Raquel likes it! The good things is that it works nicely with measurements,as illustrated in the video below, it just deserves a second chance for fabrication and integration.

This item is one of a small collection of two. I tell you more about the other piece in a separate post. In case you are wondering what is the purpose of this garment anyway, or what can we do with it, then kindly check the previous post.

Hasta luego.

It seems quite interesting using natural surfaces, as skin or leaves as a reflector to sensor readings. It could be fun walking around with it. Adding a small data logger chip to the sensor, can help us record and visualize data over time, from different walks.

The visualizations using reflections on plants and body are quite interesting; something that is worth further investigations in the future iterations.

The video below sumus up what happened at the park. Watch in HD for best quality.

The behaviour is very straight forward: Each +byte has a color, so 1 byte increase is yellow, 2 bytes is green, 3 bytes is orange, and anything above 3 is red. This is a GSM antenna at 900Mhz and the video is taken by a mobile camera, so the closer the shot, the more red and orange the colors tend to be.

Using the same logic as the lights video, this one makes different tones based on previous reading. You can hear the difference when the phone camera comes close. No?

This is a 33cm GSM loop antenna for 900 MHz. Wire thickness is 1.5mm (less than that doesn’t work!)

Well, am not a huge fan of data visualization, but it is always cool to try.   So, in the video below, using Mozzi library, am building tones while using the data input from the sensor to control modulation speed.  The same data is used to control hue colors in this cool visualization _this is a manipulation of an already manipulated SinWave code by Daniel Shiffman_

The window on the right is an oscilloscope simulator, connected directly to pwm output to get better data around variations in the built tone.

Turn volume low, because this is loud and strange.    Enjoy!

//Please don’t share on front page

So I while investigating more antenna options and optimizations, am building an output prototype. First am experiencing with materials. I created a mesh of PVC sheet using the laser cutter. I like the texture and the feel and how it resembles am emf field volume, however I need to bleach it and I probably need to multi-layer it, add more volume and define a different outline.

Thanks to Anya for modelling

Below is a sample video of translating sensor readings to tone. The melody in the video is constant, given that the sensor isnt moving or affected by anything so readings are almost constant.

Now for remaining 3 weeks, I need to work on different wearable with embedded antennas that correspond to different bandwidth. The GSM 900Mhz antenna can be triggered by phone, am now finding ways to trigger other frequencies. One option could be to make twin pieces that work together!

I made a quick mock up for the wearable and the embedded Bi-Quad antenna, and more to follow:

Quick paper mock up to demonstrate size and usability. Next is applying over a mesh material

Resembling a bow-tie, the Bi-Quad antenna works interestingly as part of the item.

900Mhz antenna field outline demo

I built the sensor chip and tested it, in order to get a sense of how data would look like and how sensitive it is. I tested with different antennas for 2.4 Ghz (which is Wifi Frequency), well, the fractal antenna seems to do better, but still, nothing is incredibly sensitive.

So this is a video of the sensor working with a wire loop antenna for 2.4GHZ.

And my story with fractal antenna goes long:

Milled antenna (well, machine focus isn’t awesome with large boards! )

Copper sticker was faster to implement

This is an ongoing trial for weaving an antenna or making crochet antenna. Looks crazy, but worth trying!

Well, it is like we need to talk to the wave in order to interact with it, and the way how to grab its attention is the antenna. There is a relationship between antenna design and the bandwidth, so what works for GSM doens’t work for FM etc..and since we are talking about ambiant radiations, so we need to talk to different bandwidths, where each needs different solution. Below is a little block diagram of how the process should go:

So, we need an antenna that corresponds to the bandwidth we are addressing, then we need a piece of electronics (RF amplifier that transmits and output voltage that corresponds to the field intensity), then we need to do something with this voltage coming out, so that it is representative enough in terms of visualization. Clear?

Until that point of research, I was still focused on the idea of _seeing is believing_ and in that sense we need to figure out a system that depends on triggering lights or any other seen effects, so I was thinking on one of the below applications, I sketched other ideas related to augmented reality and car antenna, but things radically changed, as time went by

The purpose of this research is to find ways to interact with electromagnetic waves. Visiualize them. Hear them, any method that would give voice to this unseen which defines our daily lives.

I have an interest the unknown and I like to be surprised. In the beginning of the research phase, I outlined a few topics_as thinking out loud _ then I decided to follow my passion and dig more into electromagnetic waves subject and see where it can lead to, and if it would eventually link to application of data mining (which was my second research proposal)

It has been a long journey of research, where my general knowledge about the field wasn’t much experience in the field wasn’t much in the beginning and my technical expertise in measurements was almost nothing. Nada!

Below are some aspiriation and how my learning process started, bit by bit from experiments carried out in 1800s all the way to the most recent and tiny gadgets. And the story goes long as the need for waves detection is mostly bound to commercial application or military research, which defines a lot of capabilities of what could be done and what the technology can offer at the moment.

0. Tesla’s basic application:
Tesla’s coil is used to produce high voltage, low current and high frequency AC. In practice, it is not a direct application of waves visualization, yet it creates a strong and vivid evidence of charges!

1. Elastomer Electronics:

Radio frequency responsive fabrics, with embedded stretchable antennas and integrated RF radiation sensor

2. Joyce Hinterdings’s work:
Joyce is an Australian artist, her work focuses on VLF (3kHz -30khz), a very low frequency which interacts with electromagnetic waves passing through domestic use electrical wires, NFC, and body electromagnetic waves.

3. RF sniffer (80MHz – 6GHz)
Similar to all application that depend on EM sensor in mobile phones, this company is even making them smaller and with larger range. Just released, a tiny products that detects the presence of high frequency ambient waves and generates an alarm as a response.
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4. Energy harvester (with two models that deal with different wave bands):

Somehow related --Dennis Siegel designs a harvester that converts electromagnetic waves to electricity. The accuracy depends on orientation of the device and the coil’s reaction to waves,

A couple of years beforethis device, harvesting modules have been produced by a US company. This is in general an interesting idea, but has lots of tech problems in application.

5. Fractal antennas

Related to the above, but a bit diverse. Based on fractal geometry fractal antennas, first showed up in 1995, to solve the issues of high gain, multi-band, omni-direction and small sized antennas. Research carried out is mostly related to the army, with some commercial products. I love them!

Well, lots of stuff and info, next is how I put the pieces of the puzzle together..