Recent applications of hydrogels in food safety sensing: Role of hydrogels

Access to safe food is critical for human health. Therefore, efficient sensing of hazardous substances in food is highly demanded. Hydrogels with three-dimensional polymer network structures have advantages of large surface area, easy-to-functionalize structure, excellent biocompatibility, flexibility, and mechanical stability. In recent years, stimuli-responsive hydrogels have aroused great attention in the sensing field for food safety monitoring. In order to obtain a better comprehension on the recent advances of hydrogels in real-time food safety monitoring, this current review presents the recent applications of hydrogel-based materials in developing various sensors for determination of harmful substances in food. The applications are compared, discussed, and summarized depending on the mode of signal transduction. The sensing mechanism of each application are outlined, and the role of hydrogels in each sensing strategy are highlighted. Challenges faced by hydrogel-based sensors and future trends are also discussed. Hydrogel-based materials have demonstrated admirable performance when employed in food safety monitoring based on the target triggered optical, electrical, chemical, or biological signals analyzable by transduction systems. Despite hydrogel-based materials have exhibited great potential, continuous efforts are still needed before they could be widely used in commercialized food safety control systems. With the development of novel synthesis and functionalization strategies, hydrogel-based sensors are expected to further promote the efficiency of food safety sensing. What's more, through combination with smart sensing devices, the hydrogel-based sensors are facing remarkable improvements in the applicability of the fabricated sensing systems.