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Key benefits of design are:
· Extremely low cost <1 $ to manufacture sensor
· Accurate inspiratory and expiratory spirograms
· Measures low frequency tones
· Hurricane wind force tested
· Sterilizable
· Not sensitive to physical movement
· Very low baseline drift
· Reproducible
· Flexible form factor
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- Figure 1. Cross comparison of the prototype using FeatherTone™ technology ----- versus a $3,000 Pneumotach ¤¤¤¤(black diamonds).
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Figure 1 presents a simultaneous series measurement with a commercially available spirometer. The data are remarkably similar. The FeatherTone™ instrument shows additional fine structure that is not related to noise. Frequency analysis of the time domain signal indicates a vibration 90 and 70 Hz. This vibration was repeatable and not observed with another patient. We believe that this is clinically significant and are actively pursuing clinical causality. This vibration was not observed in wind tunnel calibration runs. Our FeatherTone™ sensor are sensitive to sounds and can pick up vocal cord emanations with delicate sensitivity.
Our first trial was on 9/10/09 and spirographs were measured for two subjects: 3 trials for an adult male and 5 trials for an adult female. The pneumotach was placed in series and simultaneous measurements taken. Cross comparison of the results for the forced expiratory volume after 1 sec (FEV1) shows significant accuracy (R2 = .9966).
Likewise the forced expiratory vital capacity, which is an integrated quantity, compares extremely well with the pneumotach (R2 = .9806). For Subject 1 two data points are overlapping.
