## 4 Discussion
### Comparative Analysis of the Proposed Piezoresistive Chest Band with Similar Devices  
This section reports a comparative analysis of the proposed piezoresistive chest band with similar devices for monitoring breathing activity to highlight the main contributions and the performance of the developed wearable system. Table 5 summarizes some wearable piezoresistive RR devices, comparing them with the proposed chest band from the point of view of the used sensing device, processing unit, sampling rate, availability of wireless communication, and wearability. The sensing systems in [59; 60] offer excellent performance in terms of minimum detection limit but lack wearability since they are designed for fixed or portable instruments. Moreover, the solutions proposed in [60; 61; 62] show good reliability but are obtrusive for the users since they require a large band on the upper part of the human body. The proposed chest band relies on a custom strain sensor realized with pressure-sensitive textile (model LTT-SLPA-20K, manufactured EeonTex) and flexible electrodes. The design and realization of the strain sensor are considered to be an advantage of the proposed activity compared to other similar works using commercial strain/pressure sensors [8]. Compared to similar systems [21; 24], the developed chest band combines piezoresistive and inertial sensors for removing the body artefacts induced by body movements, thus improving the detection of the breathing parameters, as presented in [29]. Furthermore, the chest band integrates a BLE module, which is an energy-efficient communication protocol that  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Seated**} & \multicolumn{4}{c}{**Standing**} & \multicolumn{4}{c}{**Walking**} \\ \cline{2-13}
**Patient** & **r** & **MD** & **LoA** & **ME** & **r** & **MD** & **LoA** & **ME** & **r** & **MD** & **LoA** & **ME** \\  & **[adim]** & **[BrPM]** & **[BrPM]** & **[\%]** & **[adim]** & **[BrPM]** & **[\%]** & **[adim]** & **[BrPM]** & **[\%]** & **[adim]** & **[BrPM]** & **[BrPM]** & **[\%]** \\ \hline
1 & 0.958 & 0.8 & +3.47\({}^{\mathrm{\text{\text{\text{\textasci  
significantly reduces the power consumption compared to other systems employing other communication technologies (Classic Bluetooth, WiFi) [21; 25; 29; 56; 63]. Finally, the presented chest band is less intrusive than the device in [26], which uses six piezoresistive sensors distributed on the abdomen, unlike the designed device, which uses a single sensor applied on the chest. In conclusion, a performance comparison of the realized RR monitoring device with other similar systems based on the piezoresistive sensors is presented in Table 6.  
As is evident from Table 6, the performance of the developed chest band is in line with that provided by similar RR monitoring systems based on piezoresistive textiles. The system proposed in [65] employs yarn-based sensors to improve the sensing characteristics. The experimental results demonstrated that the proposed RR monitoring system obtained the lowest mean error (as shown in Table 6), which was obtained with the use of a high-resolution acquisition board (16-bit NI PCI-6024 A/D card) followed by an offline post-process through a PC. Similarly, the system presented in [29] achieves slightly better performance (2% mean error) than the presented chest band due to the employment of a 16-bit acquisition stage (i.e., NI-USB6003), thus enabling it to detect quick and small movements related to breathing. In addition, the device in [29] uses two strain sensors