A Stretchable Extrusion Printed Piezoresistive Strain Sensor for Respiration Monitoring

We introduce a wearable respiration monitor system manufactured utilizing direct write extrusion printing techniques. The proposed system features a flexible, stretchable strain sensor, constructed from piezoresistive carbon ink printed on a thermoplastic polyurethane (TPU) substrate. Integrated upon a lightweight nylon band, the sensor is positioned around the patient’s torso to detect respiratory movements. As the patient breathes, the band stretches, causing the sensor to experience lateral elongation. This deformation alters the sensor’s resistance, a change that is quantitatively measured by an adjoining resistive divider circuit. Key advantages of this respiration monitor compared to knitted e-textile implementations include its low-cost production, ease and rapidity of manufacture, and the use of comfortable, breathable, and unobtrusive materials. Furthermore, the system demonstrates excellent sensitivity with a gauge factor of 22.5, making it an ideal solution for continuous respiratory monitoring in various healthcare settings.