Comparative tests are executed between your conventional fist BVP alarm and you may the system recommended whenever victims have condition regarding impulsive breathing. 5 . They shows that the new noncontact product is comparable to contact device as a display out-of heart rate ( Fig. 5(a) ), and the difference in the results measured from the both gadgets try in this 3beat/minute. One another result of clean air saturation also are inside the a beneficial contract having each other ( Fig. 5(b) ).
Fig. 5 Scatter area indicating noncontact device’s dimensions out-of heart rate and you may fresh air saturation as opposed to the new contact device’s aspect. (a) heartbeat. (b) clean air saturation.
As can be seen from Fig. 5(a) , the heart rate obtained from the noncontact device proposed is generally in agreement with that of the finger BVP sensor. We have analyzed the results by Bland-Altman method in order to quantitatively describe the consistency of both devices. Figure 6(a) shows the Bland-Altman plot based on the results shown in Fig. 5(a) . Assuming that the mean difference between the devices is normally distributed, 95% confidence interval can be calculated at d ? ± 1.96 ? Sd ( d ? = 0.6238beat/min is the mean of the difference between measurements by both devices, and Sd is the standard deviation between measurements of both devices). The difference between measurements by both devices is within the limitation of confidence interval. It indicates that the results measured by the non-contact device are in good agreement with that by the finger BVP sensor, and they can be used interchangeably. The consistency of the SPO2 measured by both devices by Bland-Altman method is also assessed. Figure 6(b) shows a Bland-Altman plot. One among the 30 groups of data lies beyond the limitation of d ? – 1.96 ? Sd and d ? + 1.96 ? Sd . It indicates that the accuracy of measurement by the non-contact device proposed can’t reach the level of clinical application.
Pursuing the investigations take to that have 29 volunteers, new computing consequence of each other products are given during the Fig
Fig. 6 Bland-Altman plot of the mean of the measurements by both devices for each subject versus the difference between the measurements by both devices for each subject. (a) heart rate, (b) SPO2 (The number next to the data point is the sample number at that location).
This process uses the fresh background light while the source of light, that the latest PPG code try sensitive and painful. So that the ambient light-intensity should be believed because of its influences towards test results. Y. Sun et al demonstrated the measurement away from heart rate is actually nearly blind into ambient white alter . The new test finding new has an effect on out of background light alter towards blood outdoors saturation is completed inside the darkroom with the exact same setups given that people found for the Fig. dos . The distinctions is light-averaging piece and power modifying white Led array added to play with once the lighting resource in order to replicate brand new background lighting requirements not as much as certain environment. The new cousin intensity of the fresh background white is described as the newest average gray value of the human face pixel gathered by CCD that have 520nm filter out.
Table 1 summarizes the descriptive statistics for critical evaluation of the proposed method compared to a finger BVP sensor at different ambient light intensity. It shows that the relatively stable ambient light intensity has no obvious influences on SPO2 (the average gray value fluctuation is within ± 5). Temperature is also the factor that should be considered. The test is conducted under conditions with controllable temperature and stable ambient light while the temperatures are controlled as 16 ± 1°C, 20 ± 1°C, 24 ± 1°C, 28 ± 1°C, 32 ± 1°C respectively. The blood oxygen saturation of the volunteers is measured respectively after they stayed in the conditions with different temperature for 45 minutes. It turns out that the temperature almost has no influences on the test results.