## 3 Results
### Medicine
#### 3.3.2 Respiratory Monitoring  
BCG/SCG signals can accurately detect human respiratory status [77; 78], evaluate the corresponding respiratory status of human body [79; 80; 81], and diagnose respiratory diseases [82; 83; 84]. See Table 2 for the typical research.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Research Contents** & **Researcher** & **Conclusion** \\  & **[Representative Article] (Year)** & **By comparing BCG and ECG synchronous signals, the relationship between peak R and peak J in the waveforms of these two signals was analyzed, to obtain more accurate estimation of blood pressure, for diagnosis of hypertension.** \\ \hline Evaluation of cardiopulmonary function with SGC & [PERSON] (2020) [71] & The relationship between SCG signal and VO2 max was used for in-depth exploration, to analyze the reference point of waveform, and cardiorespiratory fitness (CRF) grades could thus be accurately assessed. \\ \hline Application of SCG in diagnosis and rehabilitation of coronary disease & [PERSON] (2020) [67] & A case study of a patient after cardiac valve replacement was conducted using SCG and MRI technologies, and it was found that the morphologic changes of SCG signal during cardiac diastolic period accurately reflected the status of cardiovascular functional recovery of the patient. \\ \hline SCG/BCG for patients with aortic stenosis (AS) in home settings & [PERSON] (2020) [68] & A system was developed using SCG/BCG technology to monitor the health of patients with aortic stenosis (AS) in home settings to determine the severity of disease progression. \\ \hline Application of BCG signal in diagnosis of cardiovascular diseases & [PERSON] (2019) [65] & Detection of atrial fibrillation by means of bed-type BCG signal measurement. \\ \hline BCG signal for sleep phase analysis & [PERSON] (2017) [79] & The dynamic time warping (DTW) method was used to obtain the morphologic changes of BCG signal waveform corresponding to different postures/breathing phases to judge the phase of sleep. \\ \hline SCG for sleep phase analysis & [PERSON]. [PERSON] (2017) [80] & A machine learning algorithm was developed using SCG signal to independently extract the information from different breathing phases in the signal. \\ \hline BCG signal for diagnosis of respiratory diseases & [PERSON] (2015) [82] & The heart rate variation index was calculated, and the data of sleep phase was analyzed by means of BCG signal, these can be used for diagnosis of apnea syndrome and evaluation of the status of stress of the user. \\ \hline \hline \end{tabular}
\end{table}
Table 2: Typical Research of Application of BCG/SCG in Clinic Medicine in the Tears 2015-2020.  
BCG/SCG technology, with its characteristics of non-invasive measurement, can realize the long-term collection of the signals of human vital signs with no interference or low interference, thus very suitable for sleep screening [85; 86]. The research conducted by [PERSON] et al. [82] proposed to use BCG information to calculate heart rate variation index and determine sleep apnea syndrome. In addition, BCG/SCG technology can also produce a positive guiding effect on the patients with depression, for example, [PERSON]'s [87] team used a smart bed to monitor the sleep quality of a group of children suffering from depression, analyze their sleep quality, timely intervene in their abnormal physical status, and alleviate the risk of disease deterioration.