Aerosol jet printing process study of micro flexible strain sensors

Abstract Aerosol jet printing technology was utilized to enhance the quality of the four printing processes, with the objective of producing high-quality silver wires. Silver nanowires were used as the ink media. Subsequently, micro-flexible strain sensors were fabricated on PI substrates. A comprehensive investigation was conducted to ascertain the impact of systematic variation in four pivotal printing process parameters-sheath gas flow rate (30–50 sccm), nozzle height (8–13 mm), atomization current (0.25–0.50 mA), and printing speed (1–3.5 mm s⁻¹) on the width of printed lines, their morphology, and the resistance exhibited. The objective of this investigation was to achieve the printing of silver lines with reduced line widths and diminished resistances. Concurrently, the influence degree of these four process parameters was analyzed. Subsequent to the optimization of the parameters, the fabrication of flexible strain sensors was successfully executed, and their performance was duly validated. The test results show that the line quality of the silver wire is good and the resistance is low in the range of 40–45 sccm of sheath gas flow, 10–12 mm of working distance, 0.35–0.45 mA of atomization current, and 2–2.5 mm s⁻¹ of printing speed. Finally, the strain sensor with a line width of 40 μm was printed on the PI substrate under the conditions of sheath gas flow rate of 40 sccm, working distance of 11 mm, atomization current of 0.4 mA, and printing speed of 2 mm s⁻¹. The flexible strain sensor prepared under these conditions exhibited a sensitivity of 65.7 and a hysteresis rate of 4.37% at 0%–5% strain, adhesion rating to substrate reaches 4B level, demonstrating good repeatability.