Silk-Based Microneedle Biosensor for Sustainable Food Supply Chain

Manipulation of hierarchical assembly of biopolymers enables utilization of their functionalities for engineering purposes. Silk fibroin extracted Bombyx mori cocoons is an emerging technical material for food contact applications due to its non-toxic and edible nature. In this study, we present a silk-based microneedle injection system for food bacteria and spoilage detection. We developed internal pore structures of microneedles through the water-annealing process leading to increased beta-sheet formation. The microneedles delivered internal food fluid via capillary action in pores to a colorimetric sensor on the needle array's backside. Within a day of injection, we identified E. coli contamination and common food spoilage in fish fillets by color changes of the polydiacetylene-based sensor. We also showed that the microneedle sensor could pierce commercial food packaging, implying a successful adaptation of the technology downstream in conventional food supply chains. Therefore, this study provides insights into global food safety and food waste reduction.