The measurement of moisture in textile materials worn on or near the skin can be performed for a variety of reasons, for example, to analyze the amount of perspiration in clothing, wound fluid in bandages or even urine in diapers or bed sheets. Conventional moisture measurement methods, such as electrical resistance or capacitance measurement, can be susceptible to cross sensitivities to electrical fields or ionic impurities, often occurring in measurements close to the human body. The very reliable gravimetric methods are too bulky and difficult to be integrated in portable and online measurements. In this paper, the authors present a “transient heat moisture sensor” (THMS) which is small and comparatively easy to integrate into textiles. The authors describe the measurement principle and present a sensor element manufactured with thin film technologies. The analytical description of the sensor fits to both, experimental data and the result of first numerical analysis (COMSOL Multiphysics). The authors demonstrate how to limit the sensors spatial sensitivity to a thin layer of textile without being influenced by the adjacent environment by proper timing of the signal readout.

Moisture in textile materials worn close to the skin greatly influences our daily comfort. The measurement of moisture in textile materials is therefore of great interest, for example, to determine the amount of perspiration in clothing or car seats, the wound fluid in dressings, or even the urine in diapers or bed linen. All these applications require a robust moisture measurement method, which is harmless to humans and measures in thin layers. One method ideally suited to fit these requirements is the transient‐heat moisture sensing (THMS) method. Herein, a miniaturized and evolved adaption of the THMS method is shown. The measurement system presented herein is optimized for low energy consumption and portability. The working principle of this measuring system is demonstrated by conducting a simple test to investigate the transplanar wicking of eight fundamentally different but garment‐typical textiles. The THMS method and its ability to measure in thin layers that is ideally suited to measure moisture in thin layers are shown. Finally, it lays a foundation to enable a multitude of future applications, wherever moisture (e.g., sweat) is to be measured with high accuracy and with a wearable system close to the human skin.