Characterization of Aerosol Printing Conductive Traces and Custom Strain Gauges on PCB

Aerosol Jet Printing (AJP) is an emerging technology in the field of additive manufacturing, offering the potential for high-precision deposition of conductive traces and custom strain gauges on printed circuit boards (PCBs). Unlike traditional manufacturing methods, AJP enables non-contact printing with the capability to work on diverse substrates, making it particularly suitable for rapid prototyping, small-scale production, and the modification of existing PCBs in three-dimensional environments. This study focuses on the application of AJP for the development and characterization of custom strain gauges, using JS-A426 silver ink from NovaCentrix, a commonly utilized material in AJP for printed electronics. In this work, a custom direct-write strain gauge was developed and found to have compatible performance to that of a commercial thin-film devices. The strain gauge design consisted of an 8-leg serpentine array of 50 μm wide traces, with an overall gauge length of 4 mm and a total width of 15 mm. Following the printing process using an Optomec AJP system equipped with a 300 μm nozzle, the silver nano-particle ink was sintered using a novel hybrid technique consisting of a preliminary low temperature thermal cure followed by Intense Pulse Light (IPL) exposure to avoid the high-temperature requirements of traditional thermal sintering methods. The final printed gauge had a measured resistance of 255 Ω, slightly lower than the target value of 300 Ω due to variations in the trace thickness which is inherit to the nature of the aerosol jet spraying process. Additional reasons are further explained in the paper. The performance of the printed strain gauge was characterized by measuring its gauge factor using a 4-point bending test, which ensured accurate measurement of the strain and resistance changes. This approach offers improved consistency over traditional cantilever bending methods. The gauge factor of the printed strain gauge was found to be 1.81, slightly less than commercial thin-film strain gauges which can achieve gauge factors as high as 2.1. Despite the slightly lower sensitivity, the custom direct-write AJP printed strain gauge’s performance remains within an acceptable range for most all practical applications, showcasing the potential of AJP for producing functional strain sensors. This research not only demonstrates the feasibility of producing custom strain gauges using AJP but also highlights the advantages of AJP in terms of flexibility, rapid prototyping, and cost-effectiveness. The ability of AJP to print conductive traces and strain gauges directly onto PCBs provides a promising alternative to traditional manufacturing methods, potentially revolutionizing the production of sensors for a wide range of applications, including environmental sensing, health monitoring, and flexible electronics. Overall, the findings validate the potential of AJP in developing custom, cost-effective electronic components and paves the way for further innovations in the field of printable electronics.