Why is breath an interesting concept for an interface? Because it adds life. It's artificial, but it encourages empathic connection through suggesting a living system. Breath is intimate. The pace is something we understand deeply. The regular rhythm is something that we recognize as our own and as something belonging to those closest to us. It brings us into connection. With sensors that measure the body, the breath of the system could entrain with the user, helping lead their breathing to calm or simply synchronize to increase connection.
Watching someone close to me I noticed how their breathing and mine would sync in and out of phase. In watching their chest move in and out I felt a closer connection. I found myself wondering about how this deep signature of living things might transfer into more inanimate things, bringing a sense of connection.