Electrohydrodynamic-Printed AgNPs/PR Thin-Film Temperature Sensors With Micro Dimensions and Higher Temperature Measurement Capabilities

Conflicts between the existing temperature-resistant ink and printing window currently prevent electrohydrodynamic (EHD)-printed thin-film temperature sensors from achieving both fine linewidth and a higher temperature measurement limit simultaneously. In this study, we propose a method to adjust the existing AgNPs ink to prepare thin-film temperature sensors with micro dimensions and enhanced temperature measurement capabilities. The method involves leveraging the solubility of polyester resins (PRs) in alcohol–ether solvent to incorporate PR into a nano-silver solution in the same solvent system. This allows for easy printing while using the temperature-resistant properties of PR to anchor conductive networks. The AgNPs/PR film sensitive layer has an area less than
$800\times 800\,\,\mu \text{m}$
, with an average linewidth of under
$50 ~\mu \text{m}$
and a film thickness of approximately 700 nm. The unencapsulated AgNPs/PR film sensitive layer demonstrates long-term conductivity at 400 °C, while maintaining its structural integrity. Furthermore, performance test results indicate that AgNPs/PR film temperature sensors without encapsulation have a temperature measurement upper limit of 400 °C, but they are susceptible to oxidation drift at this temperature. To eliminate oxidation, SiO2 encapsulation is prepared. Experimental results demonstrate that AgNPs/PR film temperature sensors with SiO2 encapsulation achieve a temperature measurement upper limit of 407 °C. At this temperature, the resistance drift rate (RDR) is −0.0496%/h. After three rounds of testing, the change rate of the sensor resistance at 100 °C was −0.281%. The successful fabrication of the sensor using EHD printing suggests the potential of this sensor for applications in high-density temperature sensing requirements.