You may already know that the human body uses electricity to feel, move and think. Where this electricity originates from and what its consequences are is fascinating. Some of these signals can me measured at the outside of our body: the signals of our heart (ECG), the signals of our brain: EEG, the signals of our muscles: EMG. Sometimes we do not measure electrically but optically: PPG (actually, this is one of our favourite tools). PPG is relatively easy to measure and is a strong signal and the signal itself holds a lot of interesting information. These signals can be used to design and develop various applications, for example, health monitoring at hospital and at home, communication and bonding by bio-feedback, sport applications, or stress management.
The above image was taken from a real-time Poincaré plot during a slow breathing exercise as described in (Feijs, Langereis, Van Boxtel 2010) [published in Design and Semantics of Form and Movement, DeSForM). Working in the Industrial Design department of TU/e, particularly in the Designed Intelligence Group (DI), we have an interest and competencies in both the technological aspects of measuring the signals and also in the formgiving, how to deliver the results to their users. The results can be presented visually, as sound, or even haptic (to feel them). We also are interested in the idea of bio-feedback: to let a user sense his or her own body again, and perhaps train. Existing commercial tools such as stress-eraser are aimed at stress-reduction by resonant breathing: a fascinating idea and we like to create more options in this direction.
We have an electronic atelier, which is also used for education and a biofeedback laboratory. Our biofeedback lab is equipped with EEG sensors and we have some of the best existing biofeedback games, such as The Journey to the Wild Divine and stress eraser. But the preferred tool is a simple [PPG sensor circuit[(http://www.geertlangereis.nl/SensorWiki/doku.php) created by Dr.ir. Geert Langereis which gives us the heart beat signal derived from a finger clip. The nice thing is that we get the data in an Arduino, which makes them accessible and embeddable in creative projects and applications. Of course we are not the only group creating sensor circuits with Arduino, similar hardware/software can be found at MedicArduino, for example.
We cooperate with a network of partners such as the SPS group at the department of Electrical Engineering for signal processing, such as the psychology department of Tilburg University, the MMC hospital (see for example the Sibrecht Bouwstra's smart jacket project), Kempenhaeghe (working towards new instruments related to sleep and stress, for example Neurophysiological correlates of dissociative symptoms) and the VU Amsterdam (see for example student Kyra Frederik's project). We also have cooperated with companies such as Holst center and The Mind Connection, either using their technology, or helping them to develop new technology.
The theory and the PPG tool are also used in our education program at TU/e ID, for example in a module called Sense Your Heart designed by Dr. Wei Chen. A few of the results can be seen on Dr. Jun Hu's Sense Your Heart page.