fig4

Figure 4. Demonstration, application and functionalization of the respiration sensor. (A) A sample data of an average individual’s inhalation and exhalation pattern variation; (B) Calibrated output voltage and calculated air pressure from three volunteers’ breathing profiles; (C) Breathing profiles of Volunteer 3 before and after COVID-19 diagnosis; (D) Breathing profile for normal, meditation and exercise states; (E) IMT device assembled from a modified respiration sensor with added airhole obstruction components composed of three different shapes and designs of airholes; (F) Calibrated output voltage of maximum peaks from inhalation and exhalation breathing profile of a volunteer using the IMT device; (G) Inhalation and exhalation characterization plot (calibrated output voltage plotted against increasing air pressure) for respiration sensor modified with three different thicknesses of PDMS membrane. Error bars that are not visible are smaller than the symbol size; (H) Deep breathing measurements from two volunteers using a modified respiration sensor with PDMS membrane thickness of 2.0 mm; (I) Linear regression plots (of sensors with PDMS t = 2.0 mm) showing predicted output voltage for deep breathing ranges. IMT: Inspiratory muscle training; PDMS: polydimethylsiloxane.