Table 2.

Comparative analysis of nano-enabled smart packaging sensors.

Mechanism	Sensing Principle	Nanomaterials Used	Target Analyte	Application
Colorimetric	pH/gas-triggered dye change	ZnO (with anthocyanins as colorimetric agent),	Volatile amines	Spoilage detection in meat
Fluorescence-based	Emission under UV light	Quantum dots, CDs, ZnO	Microbial metabolites	Dairy spoilage sensors
Electrical conductivity	Resistance/capacitance shift	CNTs, graphene, metal oxides	Pathogens, gases	Sensor chips in seafood packs
Gas sensing	Chemisorption	SnO2, MWCNTs, Ag-doped ZnO	NH3, H2S, CO2	MAP packaging freshness tracking
Time–temperature	Thermal response of indicators	PDA/Ag NPs	Cumulative heat	Cold chain integrity