Table 4.

Output performances of PEH and TEH.

Reference	Harvester Size	Voltage (V)	Power	Power Density	Frequency (Hz)	Optimal Load
1. Piezoelectric energy harvester
Panthongsy et al. [1]	2.80 cm3	7.57	0.58 mW	2.07 mW/cm3	20.83	99 kΩ
Yang et al. [50]	241 mm3	22.50	2.53 mW	10.50 mW/cm3	44.00	200 kΩ
Dai et al. [51]	2.26 cm3	24.47	1.06 mW	0.47 mW/cm3	51.00	564.7 kΩ
Sriramdas et al. [52]	108 mm3	3.96	8.1 µW	0.08 mW/cm3	30.80	1 MΩ
Ma et al. [53]	270 mm3	1.46	3.18 µW	0.012 mW/cm3	93.00	700 kΩ
Dhakar et al. [54]	102.08 mm3	6.32	40 µW	0.39 mW/cm3	36.00	1 MΩ
Lee et al. [55]	0.023 mm3	0.84	1.38 µW	61.3 mW/cm3	255.9.	510 kΩ
Song et al. [56]	0.11 mm3	0.03	0.023 µW	0.209 mW/cm3	48.00	40 kΩ
Zou et al. [57]	400 mm3	12.29	387 µW	0.968 mW/cm3	9.90	390 kΩ
Morimoto et al. [58]	0.26 mm3	0.51	5.3 µW	20.46 mW/cm3	126.00	50 kΩ
2. Triboelectric energy harvester
Zhang et al. [5]	18.75 cm2	36	162 µW	86.4 mW/cm2	-	8 MΩ
Jurado et al. [6]	64 cm2	3.83	307.88 µW	19.24 µW/cm2	150	10 MΩ
Shamsuddin et al. [17]	118.16 cm2	40.00	17 µW	0.14 µW/cm2	-	60 MΩ
Yang et al. [18]	36 cm2	749.40	9.36 mW	260 µW/cm2	3.2	60 MΩ
Uddin et al. [19]	2.28 cm2	16.20	36 µW	15.8 µW/cm2	3	1 MΩ
Xia et al. [26]	6 cm2	48.00	2.88 mW	480 µW/cm2	-	800 kΩ
Kim et al. [27]	36 cm2	13	210 µW	48 µW/cm2	-	20 MΩ
Mule et al. [29]	4 cm2	774.59	10 mW	2.54 mW/cm2	-	60 MΩ