Calm technology for biofeedback : why and how?

We discuss several possibilities and fundamental difficulties when designing biofeedback systems based on calm technology. As a carrier for the discussion we develop a novel biofeedback installation based on heart rate variability. The system is built-in to an elegant table and gives visual feedforward or feedback for relaxation based on breathing. When in feed-forward mode, the system will show a sine wave of about 7 cycles per second, close to the well-known resonant breathing frequency. Alternatively, the amplitude of the movement can give feedback on the heart rate variability level, which is known to be directly associated with a reduced level of mental stress. The demonstrator has a pulse- plethysmography sensor which measures the beat-to-beat intervals of successive heart beats. The mechanical design of the actuator is designed to operate completely noise-less. Both the adaptive algorithm and the actuator are new to the best of our knowledge. Still new fundamental questions arise.