With the development of society and the progress of technology, people are paying more and more attention to flexible wearable electronic devices. The development potential of electronic smart textiles is huge and the market prospect is extremely broad. Smart textiles are widely used in human physiological signal monitoring, pressure, temperature and humidity detection, energy storage, gas sensors, and biosensors.
Among them, the detection of humidity is closely related to human life. For example, it has applications in various fields such as construction, chemical pharmacy, food, and agriculture. However, humidity detection often faces interference from a variety of other conditions. Therefore, the selectivity and stability of the humidity sensor in different working environments become extremely important.
Metal organic framework (MOF) materials not only have the highly regular morphology of inorganic materials, but also have the characteristics of multi-chemical functions of organic materials. Therefore, MOF is one of the ideal materials for preparing smart textiles. Based on this, researchers from King Abdullah University of Science and Technology in Saudi Arabia used MOF as the active functional layer to functionally modify both linen and cotton fabrics to prepare a high-performance flexible humidity sensor (TEX).
Performance comparison of different substrate MOF humidity sensors
Researchers used Langmuir-Blodgett (LB) technology to directly deposit MIL-96 (Al) MOF film on the surface of linen and cotton fabrics, respectively. The test results show that MOF has a higher coverage rate on the surface of linen fabrics than pure cotton fabrics. High and humidity sensing performance is more excellent.
MOF deposition coverage test on fabric surface
From the SEM morphology characterization point of view, the fiber diameter of linen fabric is smaller than that of cotton fabric, and the arrangement is more regular, which is more conducive to the deposition of LB functional film on the surface. Therefore, the MOF coating is more uniform and dense on the surface of linen fabric. The sensing performance of TEX based on linen fabric is even better.
SEM image of fiber and its surface
System testing shows that the prepared TEX has excellent cycle performance stability, and still has sensitive and stable humidity responsiveness under different temperature conditions and after storage for up to 3 weeks.
Humidity sensor cycle performance test
In addition, the research team tested the humidity sensor's selectivity to moisture under mixed atmosphere conditions. In a mixed atmosphere of water, methanol, ethanol, acetone, benzene, toluene, and chloroform (VOCs 5000 mg/kg), TEX exhibits obvious high selectivity to water vapor. The research results have certain guiding significance for the application of MOF materials and other nano-functional materials in the construction of smart textiles.
