Fig. 2: Operational principle and characterization of the sensor.
From: A flexible catheter-based sensor array for upper airway soft tissues pressure monitoring
a The simplified electrical model of the flexible piezoresistive sensor. b Simulation results of piezoresistive sensors’ microstructural elastomeric contact deformation reveal the relationship between SC and applied pressure. c The relationship between the external pressure and sensor resistance change (ΔR). d Photograph of the catheter after the microstructure has been etched on the catheter wall by femtosecond laser. Scale bar = 5 mm. Inset: enlarged view of the triangular cross-sectional microstructures on the catheter wall under a metallurgical microscope. Scale bar = 100 μm. e SEM image of uniformly distributed microstructures etched on the catheter surface by femtosecond laser. Scale bar = 100 μm. Inset: magnified side-view SEM image of the microstructures. Scale bar = 100 μm. f Resistance change (∆R) versus different pressures for sensors with the aspect ratio K = 1:1 at various depths (100, 80, 50, and 30 μm). g Resistance change (ΔR) versus different pressures for sensors with the same depth of 100 μm at different widths (130, 100, 70, and 50 μm). h Relative change in sensor resistance response during 200 cycles of compression testing. i Response time of the sensor when 30 mmHg pressure is applied. j Resistance change (∆R) versus different pressures for sensors in the natural state and the 10 cm diameter bent state. k Resistance responses of each sensor unit in the same sensor array over the target pressure range.
