Table 4.

The summarization for the development of wearable sensors based on NGs.

Type feature	Tactile sensors	Motion sensors	Strain sensors	Others
Size (cm)	1.5 × 1.5 [124] 1 × 1 [128] 2 × 1.5 [129] 6 × 3 [130] 5 × 5 [131]	7.1 (Φ) [119] 150 [133] 2 × 6 [134] 10 × 6 [135] 0.01 (thick) [136] 20.32 × 29.46 [137] 3 × 1.6 [138]	1 × 1 [106] 2 × 1.8 [109] 2 × 1 [139] 1 × 2.5 [141] 5 × 5 [143]	7.5 × 5 [106] 25 [145] 1.5 × 1.5 [107] 2.5 × 3 [116] 2 × 3 [147] 3.5 × 3.5 [148]
Sensitivity/output voltage	0.99 V·kPa−1 [128] 0.39-1.46 V·N−1 [129] Uniaxial strain 1160% [132]	0.06 V·N−1 [133] 45.5 mV·K−1 [134] Over 2000 V·m−2 [137] 72 V/ε (ε = ΔL/L0) [138]	2.0 V [106] 29.4 mV [139] 0.16 W·m−2 [143] 49.7 V [143] 1.2 V [144]	0.55 V·kPa−1 and 0.1 V·°C−1 [107] <0.1 K and >28.9 kPa−1 [147] 42 V [148]
Position/accessory	Finger [124–126, 128] Finger skin [127] Finger and hand [129] Hand [131, 132] Wrist [130]	Hand and chest [119] Sock [133] Elbow and wrist [134] Arm and leg [135] Wrist, foot, elbow, knee [137] Cap or jaw [138]	Joint [106] Forearm, shirt, pants [109] Abdomen [117] Thumb and wrist [140] Finger [141, 144] Cotton glove [142] Finger, elbow, arm, knee [143]	Elbow, leg, neck [106] Respirator [108, 145, 148] Finger [107] Waist and abdomen [116] Hand and fingertip [147]
Flexibility	Yes [124–132]	Yes [133–138] None [119]	Yes [109, 117, 140–144] None [106, 139]	Yes [108, 118, 147] None [107, 108, 145, 148]
Stretchability	Yes [124–126, 129–132] None [127, 128]	Yes [135, 138] None [119, 133, 134, 136, 137]	Yes [117, 140–144] None [106, 109, 139]	Yes [106, 147] None [107, 109, 110, 118, 148]
Types of nanogenerator	PENG [128, 132] TENG [125–127, 129–131] PYENG [124]	TENG [135, 136, 138] Hybrid [119, 133, 134, 137]	PENG [139, 144] TENG [106, 109, 140–143] Hybrid [117]	TENG [107–110] PYENG [147, 148] Hybrid [116]