Investigations on 3D printed PETG based smart containers for online health monitoring of food articles

Abstract

Polyethylene terephthalate glycol (PETG), a food-grade thermoplastic, is widely used in food articles (FA) packaging. However, the application of 3D-printed PETG smart containers for the online health monitoring of FAs remains underexplored. This study investigates the feasibility of recycling waste PETG for sensor fabrication and optimizing its performance. newlineWaste PETG was subjected to four recycling cycles, followed by comprehensive mechanical, rheological, thermal, FTIR, and SEM analyses. The results confirmed structural stability and improved mechanical properties after recycling: Young s modulus (E) increased substantially by 42.8% (from 0.586 GPa to 0.737 GPa, corresponding to a porosity decrease (26.54% to 19.19%). Flowability saw a significant 186.98% increase, with a negligible change in the glass transition temperature (Tg). These findings suggest a material limitation of four recycling cycles for sensing applications due to a 113.29% increase in electrical resistance. newlineSubsequently, the fused filament fabrication (FFF) process was optimized for maximum tensile strength using a Taguchi L9 array, considering nozzle temperature (NT: 235/240/245 °C), infill density (ID: 60/80/100%), and printing speed (PS: 50/55/60 mm/s). The optimal FFF setting (NT 245°C, PS 55 mm/s, ID 100%) yielded a substantial 43.68% improvement in tensile strength. newlineFinally, 3D-printed ring resonators (RR) and microstrip patch antennas (MPA) were tested for environmental sensitivity. The RR exhibited a radio frequency (RF) shift from 2.744 GHz to 2.718 GHz under moisture and a 2.769 GHz to 2.680 GHz shift with temperature increase (20°C to 60°C). The MPA demonstrated even higher sensitivity, with a significant RF decrease from 2.948 GHz (dry) to $2.712 GHz (5 ml) and 2.948 GHz at 20°C to 2.400 GHz at 70°C. The consistent and measurable response of both RR and MPA proves their viability as integrated sensors within recycled PETG containers for continuous health monitoring of food articles. newline newline