Impact of Analyte pH on the Sensitivity of Screen-Printed Flexible Ammonium Sensor

This work reports the impact of analyte pH conditions on the sensitivity of the Ammonium (NH4+) sensor. The NH4+ sensor was developed by screen printing an IDE structure and subsequently modified with multiwalled carbon nanotube (MWCNT) and Zinc Oxide (ZnO) nanocomposite active layer on a fiber epoxy substrate. The sensor impedance response was studied for the varying NH4+ analyte pH levels, and device sensitivity was found to decrease with increased analyte pH concentrations (pH 4 - pH 9). The maximum impedance of the sensor operated at pH 4 was similar to 10.5% higher when performed at pH 9. The outcome demonstrates that the presented study could open new opportunities to develop highly sensitive nutrient sensors based on tuning of the analyte pH conditions. Alternately the study highlights the need for maintaining analyte pH conditions for the stable and reliable response of the flexible ammonium sensor.