Immaterials: the ghost in the field

This video is about exploring the spatial qualities of RFID, visualised through an RFID probe, long exposure photography and animation. It features Timo Arnall of the Touch project and Jack Schulze of BERG.

The problem and opportunity of invisibility

RFID is still badly understood as an interactive technology. Many aspects of RFID interaction are fundamentally invisible; as users we experience two objects communicating through the ‘magic’ of radio waves. This invisibility is also key to the controversial aspects of RFID technology; once RFID antennas are hidden inside products or in environments, they can be invoked or initiated without explicit knowledge or permission. (See here for more on the invisibility of radio.)

But invisibility also offers opportunities: the lack of touch is an enormous usability and efficiency leap for many systems we interact with everyday (hence the success of Oyster, Suica and Octopus cards). But there is also the ‘magic’ of nearness one of the most compelling experiential aspects of RFID.

As designers we took this invisibility as a challenge. We needed to know more about the way that RFID technology inhabits space so that we could better understand the kinds of interactions that can be built with it and the ways it can be used effectively and playfully inside physical products.

The experiments

In order to study the readable volume around an RFID reader, we built experimental probes that would flash an LED light when they successfully read an RFID tag. The readable volume is not the same as the radio field, instead it shows the space within the field in which an RFID tag and an RFID reader will interact with each other.

RFID probe (6 of 7)

One version of our probe containing a tag and LED light connected to the RFID reader that is being studied.

In a dark room, the probes were moved around the various RFID tags and readers that we wanted to study, with a camera taking long-exposure photographs of the resulting patterns of light. In this way we could build up layers by slicing through the field in different ways, creating animations that clearly reveal the spatial properties of this interaction.

These experiments were carried out in order to help us flesh out our own models of the technology, and were not intended to be scientifically accurate. So although they accurately reflect the behaviour of the technologies in the situations that we work with, there were no controlled environments or settings for generalisable technical accuracy.

Innovations ID 20

The Innovations ID 20 RFID reader has become one of the standard components in a lot of our work, it is small, robust and relatively cheap. So it has been very important for us to gain an understanding of the readable volume it produces when we embed the reader inside products such as Sniff and Skål.

Field drawing ID20e

Details: Innovations ID20 low-frequency EM4102 reader, 20mm circular EM4102 tag.

The resulting visualisation shows the way in which we have mapped the boundary of the readable volume, although a tag will read anywhere inside this, we have only mapped the edge for the sake of clarity. From the animation (see the video) we start to clearly see that the readable volume is made up of a strong central sphere, accompanied by a smaller lobe that surrounds the edge of the reader.

Oyster card

Mifare cards are one of the largest public applications of RFID, used in many transit systems around the world such as the Oyster and Suica cards. It has become common to have to touch in and touch out of subway stations, and many people have become accustomed to this interaction. So what does the readable volume around an Oyster card look like?

field drawing rfid oyster

Details: Standard Mifare Oyster card, probed with a Sonmicro high-frequency reader.

With a square antenna inside the Oyster and the Sonmicro reader, we get an elongated main volume, accompanied by long skinny lobes on each edge of the card. This looks very different from the ID 20 mapping.


The first two mappings held the reader and the tag parallel to each other, but we predicted that there would be a higher degree of complexity in the relationship if the tag and the reader moved in different orientations. The rig below was built so that we could control the angle between the reader and the tag, which moved along the surface of the table.


Details: Innovations ID20 low-frequency EM4102 reader, 50mm circular EM4102 tag.

There is clearly enormous physical complexity in this relationship, in the animation we can see the volume growing and shrinking, lobes turning into spheres, and vice-versa. But the animation gives us a very clear picture of the ‘throw’ of the reader onto a single two-dimensional plane, almost like looking at it as a torch.

Parallel and perpendicular

To show the two extremes of the relationship between orientation and the readable volume, we created two mappings, one with the tag parallel to the reader, and the other with the tag perpendicular. We mapped them using two different colours of LED: green for parallel and red for perpendicular.


Details: Innovations ID20 low-frequency EM4102 reader, 20mm circular EM4102 tag.

This image is a composite of the two mappings (see the video for animations of the two mappings separately) and it is clear that the readable volume is significantly different. When the tag is perpendicular to the reader, there is a sizeable gap in the middle of the reader where the tag will not read, creating two readable volumes side by side.


We have been continually challenging the ways in which RFID technology has been framed. It is incredible how often RFID is seen as a long-range ‘detector’ or how little relevant information is contained in technical data-sheets. When this information is the primary material that we are working with as designers, this is highly problematic. By doing these kind of experiments we can re-frame the technology according to our experience of it, and generate our own material knowledge.

One of the early motivations in this project was the way in which the animations really captured our tacit, embodied knowledge of the readable volume in a visual way, it was almost as if you could wave your hand through the floating green LEDs and feel them. Of course we had felt it hundreds of times in experimenting with tags and readers, but we had never seen it captured in an image, in a way that was communicable to others without having them try an interactive demonstrator. With this visual material, we can communicate about RFID in ways that we couldn’t previously.

So we hope that this work goes some way towards building better spatial and gestural models of RFID, as material for designers to build better products and to take full advantage of the various ways in which spatial proximity can be used. And with this better understanding we hope to be able to discuss and design for privacy and the ‘leakage’ of data in a more rigorous way.

Field icon

RFID icon

Download a PDF file of the RFID icon.

This RFID icon is based on the shape of the ‘readable volume’. Created by Timo Arnall & Jack Schulze, it is licensed for use under a Creative Commons Attribution 3.0 Unported License.

Go ahead and use it!


The project was made by Timo Arnall and Einar Sneve Martinussen from AHO and Jack Schulze from BERG. Thanks to Jørn Knutsen for help in building the rigs.

Related things:

  1. Making radio tangible Next week we’re launching some new work that explores the spatial aspects of RFID. So before we publish that, here is a quick summary of existing work on radio, sensors and space that I’ve......
  2. Wireless in the world An ongoing Touch theme is about making invisible wireless technologies visible, in order to better understand and communicate with and about them (see a Graphic Language for RFID, Dashed lines and Fictional radio spaces).......
  3. New film: Wireless in the World 2 In this film, Wireless in the world 2, simple visualisations of radio ‘spaces’ are overlaid into urban spaces. The film has been made as a follow up to this video experiment and has been......
  4. Fictional radio-spaces In spring 2007 interaction design students at AHO participated in a research-driven course called Tangible interactions that investigated themes around RFID, NFC and the Touch project. This is one of the projects that emerged......
  5. Images of touch interfaces I’m happy to say that with great contributions from Nicolas Nova, Matt Jones and many others, the pool of images of ‘touch interfaces’ on Flickr is growing nicely. I originally asked for contributions in......

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  1. Posted 12 October 2009 at 16:07 | Permalink

    Great article guys! Truly fascinating stuff, I look forward to future experiments and I totally think you guys should push to use the field icon as a future symbol for RFID technologies.

  2. Posted 12 October 2009 at 17:18 | Permalink

    such a simple and effective way of explaining pickup fields. i love the iconography of the field too.

  3. TomM
    Posted 14 October 2009 at 0:23 | Permalink

    Clever stuff.
    Privacy folk will want to see some field strength information and also the third party eavesdropping volume. Eavesdropping implies that a third party might listen to to the tag/reader interaction at a much greater distance than the reader can excite and read the tag .
    This work is important in designing the location of reader and placement of the tag in the “as intended” tracking and inventory use.

  4. Posted 15 October 2009 at 12:39 | Permalink

    Really nice article. Apart from the beautiful way in which the magic invisible world was made visible it also gives some real insights on how big RFID fields for this particular chip are.

  5. Michael
    Posted 15 October 2009 at 20:54 | Permalink

    Very interesting. I love your approach & methods. Its very difficult to imagine the 3D space from the 2D image. There is an interesting trick though, no idea how it is called, that by toggling between two static images taken from slightly different angles, our brain creates a spatial representation. Have a look here: Maybe that’s an idea for you? It reminds a little of the Matrix ‘time slice’ principle.

  6. Posted 15 October 2009 at 21:32 | Permalink

    That’s Really ggood

  7. Ann L
    Posted 15 October 2009 at 23:07 | Permalink

    Hey Jack, great to hear what you are doing and that it’s so inspiring. Been doing work to help people get their heads round ubiquitous computing - this is the best tool I’ve seen…

  8. GCBB
    Posted 16 October 2009 at 1:38 | Permalink

    It is totally inspiring to see the sensibility you have in conveying your research. These films manage to encourage a deeper attitude of this technology than what has been shown before. And the icon sets new standards for visual communication of technology, beautiful! and I hope to see it adapted!

  9. Posted 16 October 2009 at 19:17 | Permalink

    Very nice work. Have you considered haptic feedback to provide a physical sensation of the extent of the field? It would be interesting to have a little tactile feedback in handheld tags to signify nearness. Would not be unreasonable for a powered device like a phone, although possibly impractical for a Suica card.

  10. Simon
    Posted 16 October 2009 at 20:47 | Permalink

    I like your idea to use the field shape as a symbol for rfid in general. However I think that the annulus should be slightly fatter and the lobes should be more elongated. The shape immediately reminded my of the shape of wave function of the 3-d-orbital in a hydrogen atom. I’m sure there is some mathematical, geometrical reason for that similarity. The equation for the orbital can be looked up. I personally find the actual shape prettier than you stylized version of it. Good luck with getting people to use the symbol.

  11. paul martin
    Posted 19 October 2009 at 12:49 | Permalink

    Try a bigger bulb and see if you get rf lighting

  12. david
    Posted 31 October 2009 at 0:17 | Permalink

    the effect of the field on LED helps to characterize the shape of the the different lobes.
    i’m working as radio engineer for a gsm network company. in our field, we use softwares to modelize the radiation pattern.
    see for defitions:
    thanks to these sw, we design antennaes in function of the different needs. it’s possible to get a 3D schema of the pattern and may be it could be helpfull for you to compare what you get and the theorical pattern. check ADS from Agilent for ex.
    we also use models in order to calculate the effect of the environment (forest, building, rivers and so on…) on the propagation of the microwaves.
    in the same ideas, i know it exists now pretty good sw capable to materialize EMC inside complex box with electronic components. for ex:
    10 yrs ago, it was not the case simply because the computers were not powerfull enough.

  13. Louis Delmas
    Posted 31 October 2009 at 0:23 | Permalink

    Very Stylish video, really. I like this way of “feeling” physics, instead of the usual modeling. Mixing the designer’s approach with the scientific processes is a way for the future. BUT !
    WTF ? All of that for a symbol ? Really ? You got lost in your way didn’t you ? If that was what you were looking for you could have asked a junior physicist to draw it for you… (I could get even more crazy here but I won’t because I really like the way you handled this in the first place….still …”mystification”... come on guys !)
    To finish on a positive thought; I admit it : I am jealous, you have the dream job… and I am disgusted because I get the feeling that you don’t get everything you might get out of it.

  14. Lavoisier
    Posted 31 October 2009 at 15:52 | Permalink

    Entirely agree with Louis Delmas. A great moment of poetry in the laboratory.

  15. IlievPlamen
    Posted 2 November 2009 at 12:51 | Permalink

    I realy enjoyed the video…
    I work in these systems for a few years now, but the idea of the field visualization is a great one ;-)
    By the way, I also like your icon…

  16. Posted 7 February 2010 at 20:06 | Permalink

    What a great idea, simple and effective. We did some work on improving the range of vehicle tyre tags where we increased the effective range using a mixture of approaches. Visualisation would have helped us a lot.

    I see the value of this in studying the impact ofthe environment, people, clothing on range and field. John.

29 Trackbacks

  1. [...] This post was mentioned on Twitter by timo arnall and Dan. Dan said: RT @Timo New work with BERG, 'Immaterials': the ghost in the field [lovely; like the flat '70s colour-wash on Schulze] [...]

  2. [...] Genau mit diesem Thema haben sich Jack Schulze und Timo Arnall in ihrem neuen Film nach Nearness beschäftigt, in dem sie das Funkfeld eines RFID-Lesers sichtbar gemacht haben. Ausführliche Artikel dazu bei Berg und Touch. [...]

  3. [...] This video is about exploring the spatial qualities of RFID, visualised through an RFID probe, long exposure photography and animation. It features Timo Arnall of the Touch project and Jack Schulze of BERG.I [...]

  4. By Heavyset » Immaterials: Readable RFID Volume on 13 October 2009 at 22:32

    [...] From the very intriguing people at Touch: In order to study the readable volume around an RFID reader, we built experimental probes that [...]

  5. [...] A really good visual explanation of what RFID actually is [...]

  6. [...] maravillado con los proyectos de Touch (, el último es Immaterials_ the ghost in the field. Se trata de un pequeño proyecto para comprender como poder visualizar algo que es imposible de [...]

  7. By Leapfroglog - links for 2009-10-15 on 15 October 2009 at 14:02

    [...] Links on 15 October 2009 with no comments Immaterials: the ghost in the field I think Timo and Jack have made a lovely film, and they're obviously on to something. But [...]

  8. [...] they make visible the ordinarily imperceptible fields around RFID devices. (If you haven’t, click this link immediately; I’ll wait for you to get [...]

  9. By RFID, the ghost in the field - wtf? on 15 October 2009 at 16:17

    [...] Intéressante vidéo sur une idée originale pour visualiser les champs radio sur lesquels opère une petite antenne RFID. [...]

  10. [...] More [...]

  11. By Helsinki Design Lab 2010 » Weeknote 032 on 16 October 2009 at 14:48

    [...] friends at BERG London together with Timo Arnall have released Immaterials: the ghost in the field, a second video exploring the realm of RFID and nearfield communications. [...]

  12. [...] exposure photography and animation. In order to study the readable volume around an RFID reader, Timo Arnall [] and Jack Schulze [] built experimental probes that would flash an LED [...]

  13. By Tenez vous loin des puces RFID on 18 October 2009 at 19:02

    [...] gizmodo, nearfield, [...]

  14. By RFID icon based on Immaterials on 19 October 2009 at 17:26

    [...] Touch Interaction with RFID and NFC Skip to content HomeProjectsMediaPublicationsPeopleAbout & contact « Immaterials: the ghost in the field [...]

  15. [...] designers Timo Arnall et Jack Schulze ont publié un prototype (vidéo) permettant de visualiser le volume de lisibilité d’un objet [...]

  16. By ganzkaltefuesse » Die Käsebrotedition on 22 October 2009 at 23:32

    [...] Nun zur Abwechslung mal was richtig cooles aus Norwegen. Jungs mit echt viel Zeit und einer witzigen Idee, haben sich intensiv Gedanken darüber gemacht, wie man unsichtbares sichtbar machen kann. [...]

  17. [...] on Timo Arnall’s and Jack Schulze’s [...]

  18. By Responses to ‘Immaterials’ on 26 October 2009 at 16:23

    [...] the two weeks since we launched our film Immaterials we’ve seen it spread across the internet, going much further than we anticipated (for such an [...]

  19. [...] designer Timo Arnall e Jack Schulze publicaram um protótipo (vídeo) para mostrar o volume de leitura de um objecto de [...]

  20. By the-uMe | Invisible beauty on 2 November 2009 at 2:05

    [...] and animation. It features Timo Arnall of the Touch project and Jack Schulze of BERG. More info here at and here at BERG [...]

  21. [...] the two weeks since we launched our film Immaterials we’ve seen it spread across the internet, going much further than we anticipated for such an [...]

  22. By Rendering immaterials into 3D on 8 December 2009 at 16:25

    [...] Immaterials film, that visualises the spatial qualities of RFID, inspired architect Oliviu Lugojan-Ghenciu (from the [...]

  23. [...] Immaterials - The ghost in the field What does RFID interaction look like? So simple and beautiful. Deals with issues around ‘invisible’ technologies.  By revealing the RFID volume the nearfield team have developed a symbol that could be used to represent the technology.  Watch the video at [...]

  24. [...] using the Near Field Communication (NFC) standard. Indeed, Timo Arnall and Jack Schulze’s recent work for the Touch project demonstrates the spatial qualities of an RFID device’s signal, the [...]

  25. [...] have been thinking about what does the radio around us look like.  The project “Immaterials: the ghost in the field” is about visualizing the spatial qualities of RFID from Timo Arnallof the Touch project and [...]

  26. By Designing with film on 6 April 2010 at 14:11

    [...] visualise the interactive phenomena of RFID. Many of the visual/cinematic concepts for Nearness and Immaterials were invented by exploring and experimenting with [...]

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