Aerosol Jet Printing of PVDF-HFP: Process Development and Deposition Variability

Polyvinylidene fluoride (PVDF) and its copolymers are promising for flexible electronics due to their piezoelectric performance, mechanical robustness, and biocompatibility, giving them advantages over piezoceramics for flexible sensors, actuators, and energy harvesting applications. However, while good piezoelectric character can be achieved with conventional processing methods—generally solvent casting followed by extrusion and high-voltage poling—less work has been conducted on deposition of thin PVDF films with spatial control and lateral resolution.

This work presents a PVDF printing process using aerosol jet printing, a direct-write additive manufacturing method enabling deposition of fine features while eliminating the need for a poling step. A solution composed of 1% w/w polyvinylidene-hexafluoropropylene (PVDF-HFP) in dimethylformamide (DMF) was formulated, exhibiting good wettability across a range of substrates. The solution viscosity of 1.84 cP is compatible with the printer’s ultrasonic atomization mechanism, and an operability range is established for successful aerosolization and deposition.

Stylus profilometry and atomic force microscopy show that the deposition process is capable of producing films ranging from 240 nm to over 20 μm in thickness. Fourier transform infrared spectroscopy demonstrates that the printed films can achieve up to 80.7% fraction of the piezoelectric β phase relative to the nonpiezoelectric α phase, representing a 15% increase compared with the same solution deposited via spin coating and a 76% increase relative to the raw polymer material. These results indicate that aerosol jet printing can produce PVDF films with significant piezoelectric phase content without post-processing poling.

The effects of process parameters—including gas flow rates, transducer current, and temperature stabilization via a water bath—were examined to establish a stable operating window for deposition. Despite these capabilities, the process exhibits instability, drift, and run-to-run variation in deposition behavior. This work therefore also investigates possible mechanisms underlying this variability and discusses mitigation strategies to improve reproducibility in aerosol jet additive manufacturing.