3D-printed PETG-based Smart Containers for Online Health Monitoring of Food Articles

Polyethylene terephthalate glycol (PETG) is one of the food-grade thermoplastic materials used extensively in the packaging of food articles (FA). But hitherto little has been reported on the use of smart PETG containers for online health monitoring of such FA. This work is focused on the 3D printing of PETG-based smart containers as an IoT solution, which may be helpful to estimate the shelf life of FA with a smartphone using a Bluetooth application. In this work, a ring resonator has been fabricated using a 3D-printed PETG substrate and its radio frequency characteristics were explored as a sensor for online health monitoring of FA (pickle). For experimental investigations, a solution of mustard oil (Brassica juncea), having the main constituent allyl isothiocyanate and NaCl has been prepared (1 g of NaCl in 10 ml of oil). The resonating frequency peak shift from 2.74 to 2.71 GHz was observed on exposure of PETG substrate to the solution of mustard oil-NaCl and water content (5 ml) (to mimic the effect of moisture), and the dielectric constant (epsilon) change was noticed from 2.67 to 2.73, respectively. Further voltage-resistance characterization of the ring resonator was performed and it has been observed that the resistance of PETG decreases with exposure to the solution (selected stimuli), and hence may be used as a sensor in PETG containers for online health monitoring of selected FA.