Breathe

The idea was to create a wearable sensor on the chest, that can measure breathing based on the small movements on the chest. We designed a breathing sensor based on the principle of a load cell. It consists of 4 strain gauges connected using a Wheatstone bridge. The Wheatstone bridge has an output voltage of zero when all the resistors on the bridge are balanced. Each resistor represents a strain gauge. When a strain gauge bends in one direction, the resistance of the strain gauge decreases and vice versa. We needed the bridge to be balanced when no force is applied and unbalanced when some force is applied, that way we could detect a voltage change due to the imbalance in the resistances.