Photothermal detection of food hazards using temperature as an indicator: Principles, sensor developments and applications

Photothermal sensing, due to its high resolution and spatial controllability, has gained significant attention in optical imaging for applications such as disease treatment and diagnosis, environmental monitoring, etc. It has effectively overcome the drawbacks of traditional sensors, such as susceptibility to interference, high cost, lack of portability, and strong dependency on operational procedures. Photothermal conversion-based light-responsive temperature change sensors have been proven to break limitations, serving as an alternative strategy for more potential applications, particularly in the detection of hazardous substances in food. In the current review, the principles of temperature generation in photothermal materials and the corresponding representative materials are inducted and the modulation of temperature signals in sensors and the response-dependent principle for rapid detection are discussed. The practical applications of photothermal sensors in food hazard detection and the outlook on the challenges faced are also presented in the current review. Various doped and modified photothermal materials have been shown to enable quantitative detection of food hazards through different temperature signal modulation mechanisms as well as relying on non-specific, molecular biological and immunological responses. It is hoped that the review can provide researchers with reference sources for further developments of more effective and sensitive photothermal sensors for food safety assurance for the food industry.