Table 3. Filler materials for biodegradable conductive composites [20,23,28,30,58]

Fillers	Electrical conductivity (s/m)	Biodegradation mechanism	Application
Mo	1.79×107	2Mo+2H2O+3O2→2H2MoO4 [58]	Strain sensor [20]
W	1.76×107	2W+2H2O+3O2→2H2WO4 [58]	Moisture sensor [28]PCB board [30]
Fe	1.00×107	Fe+2H2O→Fe(OH)2+H2 [58]	-
Zn	1.69×107	Zn+2H2O→Zn(OH)2+H2 [58]	NFC device [23]