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Bio FeedBack

In this section I'am listing my research on the generic term of Bio Feedback. The extent of these research is to simplify the use of brain and body feedback system and implement it in self improvement software, using hypnosis and other technics.

The bio feedback will be based on 4 layer, the actual EEG, the voice synthesis, the phrase and content for the induction and the algorithm which will bring the patient under hypnosis.

Some project on the Biofeedback


Pulse Sensor

Galvanic skin response

The Galvanic Skin response was used in the bio feed back game Wild Divine and could be a good tool to include into a complete biofeedback system


ElectroEncephalogram is a technic to read the brains waves spectrum which could be useful in tracking a patient state of mind. Thanks to few fun toys released on the market it's now readily available to connect it to the arduino board.


To improve on the arduino + eeg solution I wanted to port the code to the teensy - but someone already done that - YEAH !

#include <Brain.h>

HardwareSerial Uart = HardwareSerial();
   // Set up the brain parser, pass it the hardware serial object you want to listen on.
   Brain brain(Uart);

void setup() {
   // Start the hardware serial.
   pinMode(11, OUTPUT);
   digitalWrite(11, HIGH); 

void loop() {
   // Expect packets about once per second.
   // The .readCSV() function returns a string (well, char*) listing the most recent brain data, in the following format:
   // "signal strength, attention, meditation, delta, theta, low alpha, high alpha, low beta, high beta, low gamma, high gamma" 

   if (brain.update()) {


  • Matel Mindflex



Voice synthesis

  • Festival
  • Flite
  • Microsoft - Sun - att

Brain Waves research

Brain Waves During Hypnosis

For a long while it was thought that alpha wave patterns were characteristic of hypnotic states. It is now understood that it is theta and to some extent delta waves and 40Hz gamma waves that are predominant. Other wave patterns occur, even active beta waves, but these are due to the content of the suggestions and the images created by them.

The sequence seems to run something like this.

  • As the you relax and then close your eyes there is a brief build up of alpha waves.
  • As the induction (see about hypnosis) develops there is an increase in theta and to a lesser extent delta activity and the alpha activity drops away.
  • This continues until the end of the hypnotic deepening.
  • During the therapeutic suggestions the brain wave activity can vary depending upon the nature of these suggestions and the effect they are having. Generally during this period the delta and theta wave activity begins to slowly subside.
  • Through the whole hypnotic process there is a gradual increase in 40Hz gamma wave activity.
  • During termination the alpha activity and finally the normal beta activity returns.

This pattern is especially noticeable in highly hypnotisable subjects.

If you want to read more about this then the following article from the April 2004 issue of the American Journal of Clinical Hypnosis presents some interesting research and a review of previous ideas.

bio_feedback.txt · Last modified: 2012/03/29 10:36 by damaru