Electrohydrodynamic jet printed conducting polymer for enhanced chemiresistive gas sensors†
Electrohydrodynamic Jet Printing (EHD) enables the printing of sub-micron structures using a wide variety of materials and substrates, thus comparing favorably to many current additive manufacturing techniques. By using EHD to print polyaniline based chemiresistors, we demonstrate ammonia gas sensors reaching a detection sensitivity of 2.5% ppm−1 (limit of detection = 0.2 ppm) on glass, and 6.9% ppm−1, (limit of detection = 0.7 ppm) on flexible substrates. We quantitatively compare the results obtained from printed sensors to those prepared with conventional dropcasting, and find significant improvement. Further, we report our findings on the role of the dopant acid in the polymer structure and sensing, as well as the processability of polyaniline for EHD with the use of advanced characterization techniques. This work validates the use of EHD for printed sensors on flexible substrates, laying the groundwork for further research and development into rapid production of a host of miniaturized flexible polymer sensors.