# A Novel Magnetic Respiratory Sensor for Human Healthcare
## 3 Results and Discussion
### Real-Time Monitoring of Human Respiratory Motion in Multiple Breathing States  
In practical applications, it is essential that a sensor be able to precisely monitor a patient's breathing in various and complex states in real time [26; 27]. Existing respiratory monitoring devices are unable to provide this information. In this study, we tested the ability of the MLCR sensor to monitor a patient's respiratory motion in simple and complex breathing states. Subject 1 was instructed to breathe in two different states, namely, normal and deep breathing states. The MLCR sensor precisely tracked how their breath (breathing amplitude and rate) varied and transitioned from one state to another (Figure 4), which demonstrates the excellent capacity of the MLCR sensor for real-time tracking of a patient's health progress.  
It has been reported that breathing training can significantly enhance health and physical performance in humans [26]. A proper breath holding technique can increase the amount of carbon dioxide in our cells and help us to reveal personal issues we need to confront [27; 28]. It has been shown that breath control improves lung function, which in turn preserves the health of stem cells and improves longevity, as well as promotes the regeneration of new tissues in the brain [29]. It has been reported that daily exercise of breath control can positively impact the sympathetic nervous system and the immune system by increasing the production of anti-inflammatory mediators [26; 27; 28].  
In this regard, we explored the ultrahigh sensitivity of the MLCR sensor for real-time tracking of a patient's breathing in multiple/complex states from holding breath (State 1) to the release of breath (State 2) and the return to normal breathing (State 3). A clear understanding of this complex breathing process provides valuable information of the patient's health and may help doctors to develop an appropriate treatment plan for the patient. In our study, Subjects 2 and 3 were instructed to first hold their breath as long as  
Figure 4: Breathing patterns of Subject 1 (30 years old (YO)) in normal (State 1) and deep (State 2) breathing states. The sensor provided an accurate measure of the strength of breath at these two states. An obvious breathing transition from the first to the second state is observed.  
Figure 3: Peak-to-peak time as a function of time for three subjects aged (**a**) 30, (**b**) 36, and (**c**) 42 years old. These abnormal breathing patterns are related to those seen in Figure 2.  
they could (State 1), then release their breath (State 2), and finally come back to normal breathing (State 3). The selected test results are displayed in Figure 5.  
It is worth noting in this figure that both the subjects underwent three distinguishable states, which were precisely tracked by the MLCR sensor. Subject 2 held the longest breath for 47 s (State 1) and, after releasing the breath, took 15 s to catch their breath (State 2) before returning to normal breathing (State 3). Meanwhile, Subject 3 held their longest breath for 30 s (State 1) and, after releasing the breath, took only 10 s to catch their breath (State 2) before returning to normal breathing (State 3). Compared to Subject 3, Subject 2 breathed more regularly after releasing their breath toward the normal breathing state. These findings seem to suggest that when getting older, one's ability to hold their breath decreases to a shorter period of time, and they may experience more respiratory issues. Using this testing method, one can be aware of their current health status and be encouraged to follow an appropriate breathing control method to improve health and physical performance.