Table 2.
Analysis of sensing techniques, sensors, breathing parameters, and sensor location and size for studies of the environmental category.
| Study 1 | Technique | Sensor | Measured Parameter | Location | Size |
|---|---|---|---|---|---|
| Al-Wahedi 2019 [163] | Modulation cardiac activity | Radar | RR | Distance from subject (20–75 cm away) | |
| Chen 2019 [164] | Modulation cardiac activity | Radar | RR | Mat (below bed) | |
| Gunaratne 2019 [165] | Chest wall movements | Piezoelectric | RR | Mat | 7 × 7 cm (each sensor) |
| Guo 2019 [166] | Chest wall movements | Capacitive | RR | Mat | |
| Isono 2019 [167] | Chest wall movements | Piezoelectric | RR | Others (under bed legs) | |
| Ivanovs 2019 [168] | Chest wall movements Modulation cardiac activity |
Camera Radar |
Respiration detection | - | |
| Joshi 2019 [169] | Chest wall movements | Capacitive | RR | Mat (below baby mattress) | 580 × 300 × 0.4 mm |
| Krej 2019 [170] | Chest wall movements | Fiber optic | RR | Mat | |
| Lorato 2019 [171] | Air temperature | Camera | RR | Distance from subject (side and front, 10–50 cm away) | |
| Massaroni 2019 [172] | Chest wall movements | Camera | RR | Distance from subject (1.2 m away) | |
| Park 2019 [173] | Chest wall movements | Piezoelectric | RR | User’s mat (Chest region) | 40 × 750 × 0.25 mm |
| Walterscheid 2019 [174] | Modulation cardiac activity | Radar | RR | Distance from subject (3.3–4.2 m away) | |
| Wang 2019 [175] | Modulation cardiac activity | Radar | RR | Distance from subject (50 cm away) | |
| Xu 2019 [176] | Respiratory sounds | Microphone | RR | Others (instrument panel of vehicle) | |
| Yang 2019 [177] | Modulation cardiac activity | Radar | RR | Distance from subject (1.5 m height, 0–3 m away) | |
| Chen 2018 [178] | Modulation cardiac activity | Wi-Fi transmitter and receiver | RR Respiration detection |
Nodes | - |
| Chen 2018 [179] | Chest wall movements | Piezoelectric | RR | Mat | 2 × 35 cm |
| Massaroni 2018 [180] | Chest wall movements | Camera | RR Respiratory pattern |
Distance from subject (1.2 m away) | - |
| Massaroni 2018 [181] | Chest wall movements | Fiber optic | RR | Others (inside ventilator duct) | 3 cm |
| Sadek 2018 [182] | Chest wall movements | Fiber optic | RR Respiratory pattern |
Mat | 20 × 50 cm |
1 Note: The analysis for studies published before 2018 [5,6,7,9,10,19,48,50,51,52,53,54,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234] is included in Appendix A (Table A2).