Table 3.

Summary of the most important properties for piezoelectric and triboelectric nanogenerators [16].

		Piezoelectric Nanogenerator	Triboelectric Nanogenerator
Materials [175]		BaTiO3 and P(VDF-TrFE), AlN, polymer threads, ZnO nanowires and nanorods, PZT nanowires and ceramic, PVDF, PVDF-NaNbO3, PVDF polymer and nanofibers, Ceramic PMNZT, PTFE and Al, Al wires and PDMS	PTFE, FEP, PET, PDMS Metals—Cu, Al, Ni, Graphene Nitrile, silicone, Kapton film, PLGA-PCL, Silk fibroin, cellulose, chitin, Rice paper, egg white
Structure [176]		Spiral twining/multilayer/winding Coaxial Core-sheath Woven (2D and 3D) Twisted Sandwich E-skin	Nanofiber stacking/embedded Coaxial Core-shell Knitted/woven (2D and 3D) Textile, fibre, yarn 3D printed Sandwich E-skin
Output performance	Pulse sensor	97.5 V; 1.16 µA [177]	109 V; 2.73 µA [19]
	E-skin	3.2 V; 56.1 nA [133]	220 V; 1.12 µA [178]
	Cardiac pacemaker	3.5 mV; 60 nA [179]	136 V; 2 µA [165]
Material fabrication process		−Complex and expensive fabrication process −Ceramics are fragile and brittle	+Wide selection of materials +Relatively low cost +Easily fabricated
Power density		+High power density −Lower current density −Affected by operation frequency	+High power density +Higher output voltage +Multiple-operation mode
Sensing performance		+High dynamic sensing +Fast response −Poor static sensing	+Wide sensing range +Fast response −Poor static sensing
Scalability		+Successfully miniaturized −Expensive and fragile	+Large-area application −Low-output voltage after miniaturization
Durability		+Good mechanical durability	+Good stability of electrical signal −Poor mechanical performance −High erosion of the material −Sensitive to environment
Biocompatibility		+(Co)polymers and lead-free materials are biocompatible −Ceramics can be toxic	+Biocompatible