A Rapid and Low-Cost Lung Function Testing Method Based on an Optical Flow Sensor

Optical Fiber Fabry–Perot Interferometer Based Spirometer: Design and Performance Evaluation

“…The same figure also illustrates the theoretical wavelength shifts for the same values of flow, obtained according to (13), to provide a comparison with the underlying theory described in the previous sub-section. For the restraining factor p in (12), a value of 0.7 was considered, found through data processing. From the fit performed to the data represented in Figure 6, the values of the constants W I and W E, were found to be 66.76 L/s•(nm) 1/2 and 55.43 L/s•(nm) 1/2 , respectively.…”

“…Optical fiber-based sensors appear as an alternative capable of overcome such limitations by offering immunity to electromagnetic interferences and electrical isolation, along with low signal attenuation, high accuracy, and possibility of remote sensing [8]. So far, there are reports of solutions based on the modulation of the fiber Bragg gratings (FBG) response due to the thermal variations associated with the breathing cycles [9,10], the bending losses, or vibrations induced by the air flow that impact on the optical signal intensity [11,12], cantilever mechanisms that apply strain proportional to the air flow onto FBG-based sensors [13,14], among others. An FBG 3D printed system was recently explored by the research team of this paper, also for the spirometry application [15].…”