This article presents an end-to-end system for capturing physiological sensor data and visualising it on a real-time graphic dashboard and as part of an art installation. More specifically, it describes an event where the level of engagement of the audience was measured by means of Galvanic Skin Response (GSR) sensors and of the presenter through a sweater fitted with GSR, ECG and acceleration sensors. The gathered data was presented in real-time through a visualisation projected onto a screen and a physical electro-mechanical installation, which would change the height of helium-filled balloons depending on the atmosphere in the auditorium. Thereby trying to create a tangible way of making the invisible visible.