Research progress of non-destructive testing techniques in moisture content determination

• theoretical basis and practical applications are comprehensively reviewed. • the challenges faced in non-destructive moisture content detection is explored. • potential future route for the further development and promotion of NDT technology. • performance index of machine learning-assisted moisture sensor is point out. Accurate measurement of moisture content is crucial in various industries for improving product quality, ensuring safety, optimizing production processes, and protecting the environment. However, traditional moisture measuring methods often damage the sample and are complex and time-consuming, making it challenging to meet the high demands of modern industries for efficiency, precision, and real-time monitoring. Non-destructive testing (NDT), an advanced technology, can rapidly and accurately assess the characteristics and conditions of materials without damaging their structure, morphology, chemical components, and physical properties, making it suitable for moisture content testing. This paper provides an overview of traditional drying methods for moisture content detection and a comprehensive review of the theoretical basis of electrical resistive, capacitive, and microwave methods, including their applicable detection materials. Moreover, we analyze the advantages and disadvantages of each method. Additionally, the paper highlights that combining non-destructive moisture content detection with machine learning can significantly improve both detection efficiency and accuracy. Finally, we address the challenges associated with non-destructive moisture content detection and explore potential future developments to support the further advancement and adoption of NDT technologies.