Bio Mapping

Bio Mapping Device

Technical Info

Bio Mapping consists of 3 different components.

1 A Galvanic Skin response sensor/data logger
2 A commercial GPS unit.
3 Visulisation/Mapping software.

Galvanic Skin response

I developed the Galvanic Skin response sensor/data logger which is now progressed to version 3. While arly prototypes used hand soldered boards and wires, they have now been replaced with custom made circuit boards.

Bio Mapping Device

On the circuit board a PIC microcontroller passes a small current through one of the electrodes into the wearer's fingers and calculates how long it takes for a capacitor to fill up.

The GSR finger cuffs are based on a design from here

The length of time the capacitor takes to fill up allows us to calculate the skin resistance. A short time means low resistance while a long time means high resistance.

In itself this number is not very meaningful - i.e. one person's hands might be sweatier than another, but what is significant is the rate of change of this value over time.

The difficulty is working out all the correct timing in order to capture change and in particular the so called "Startle Response".

" GSR Physiology: Easily measured and relatively reliable, GSR has been used as an index for those who need some measurable parameter of a person's internal "state". As in EEG, there is not a clear understanding of what the measures reflect. Physiology, the GSR reflects sweat gland activity and changes in the sympathetic nervous system and measurement variables. Measured from the palm or fingertips, there are changes in the relative conductance of a small electrical current between the electrodes. The activity of the sweat glands in response to sympathetic nervous stimulation ( Increased sympathetic activation ) results in an increase in the level of conductance. There ia a relationship between sympathetic activity and emotional arousal, although one cannot identify the specific emotion being elicited. Fear, anger, startle response, orienting response and sexual feelings are all among the emotions which may produce similar GSR responses."
- Taken from Bio website


In addition to the Galvanic Skin response the device also records the wearers location every 4 seconds. This position data as well as the arousal data is stored on a large EEPROM memory chip with 256k of storage which give me about 48 hours of recording - more than enough for my purposes.


After the data has been downloaded the data is visualised using one of 3 different mapping systems.

The first is a custom a custom built software that functions like a data-driven slideshow which continuously zooms and pans through every participants walk and at intervals builds up a communal map of all the tracks. This software requires scanned maps.

Secondly, I use Google Earth to visualise the tracks after they have been converted to GPX by my custom software. The advantage of this that it is 3D, the map data is extremely high resolution and included with the application.

Third I use a tool written by Tom Carden in Processing to visualise the Bio Mapping walks. The advantage is that the visualisation can be heavily tweaked is open source and because it is 3D graphically very powerful.


This project has received technical advice and support from the following people:

Martin Yong - GSR sensors
Stevon Ritchie - Mapping software
Jeff Knowlton - Mapping software
Tom Carden - Processing mapping software

Christian Nold
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All the work on the Bio Mapping website is licensed under a Creative Commons Attribution NonCommercial ShareAlike 2.5 License. The CSS is adapted from Intensive Station

Last Updated 22.08.07


Hello I need to get feedback from people about what they think about the Bio Mapping project. Please help by filling out this online form. Thanks so much !!!


I am in Tokyo speaking and running a Bio Mapping workshop at the Dislocate 07 conference. Come and join us if you are around.


Link to all the press coveage

The San Francisco Emotion Map is complete. At the end of July I will be Bio Mapping in Tokyo. Until then I am working on my book and setting up a project in Stockport and Stoke Newington. Please see my main site for more info.


There is a new interview about the Bio Mapping project.


Bio Mapping has won the SciArt R&D award which will give me time to write a book about the project and commission some critical / historical essays around the project. If you are intersted in writing one get in touch!

Live interview on WAMU US public radio.


New articles about Bio Mapping on the Discovery Channel the New Scientist and on Slashdot in the German Telepolis, Italian MondoGIS , French Liberation and Techno Science as well as British Council magazine


A high quality MPEG4 video of the Greenwich Emotion Map is available for download


I was interviewed on BBC World Service and NewsTalk106. See Tom Hagler's walk in Covent Garden.
(requires Google Earth)


The Observer carries an article on Bio Mapping. Click on the links to view David Smith's walks in rural Bibury as well as 'Murder Mile' in Hackney.
(requires Google Earth)