Electrohydrodynamic Printed Ultra-micro AgNPs Thin Film Temperature Sensor

To achieve high-density and arrayed temperature sensing, thin film temperature sensors require a multilayer structure and miniaturized preparation technology. Currently, screen printing, direct writing by squeeze, and MEMS are the main methods for preparing thin film sensors. However, the film line width produced by screen printing or direct writing by squeeze is impossible to achieve width within 10 μm, while MEMS is costly and limited in terms of target materials. Electrohydrodynamic (EHD) printing is a promising alternative due to its ability to print multiple materials and multilayer structures with patterned films less than 10 μ m width. In this study, we propose a method using only EHD printing to prepare ultra-micro thin film temperature sensors, including a AgNPs sensitive layer and PDMS encapsulation layer. The area of the AgNPs film sensitive layer is less than 120 μm×120 μm, with an average line width of less than 10 μm, and a film thickness of less than 200 nm. The printing range of the PDMS encapsulation layer is 300 μm×300 μm, with a minimum film thickness of 567 nm. The performance test results show that the ultra-micro AgNPs film temperature sensor after EHD printing of PDMS encapsulation has a higher temperature measurement upper limit. The hysteresis error was ± 0.1309%, and the repeatability error was ± 0.3311%, both much lower than previously reported. The successful fabrication of ultra-micro thin film temperature sensors using EHD printing suggests the potential of this method to supersede MEMS for achieving high-density and arrayed temperature sensing in limited space.