Circular sensing of nitrate levels in water with flexible screen-printed sensors on biodegradable cellulose substrate

Authors: INAM, AKM SARWAR - University Of Texas; ISLAM, MD NAJMUL - University Of Texas; RIA, SHA ZAYED - University Of Texas; PEREZ, FRANCISCO - University Of Texas; Delhom, Christopher; ABIDI, NOUREDDINE - Texas Tech University; TABASSUM, SHAWANA - University Of Texas

Submitted to: IEEE Sensors Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2023
Publication Date: 8/4/2023
Citation: Inam, A., Islam, M., Ria, S., Perez, F., Delhom, C.D., Abidi, N., Tabassum, S. 2023. Circular sensing of nitrate levels in water with flexible screen-printed sensors on biodegradable cellulose substrate. IEEE Sensors Letters. 7:9. https://doi.org/10.1109/LSENS.2023.3301834.
DOI: https://doi.org/10.1109/LSENS.2023.3301834

Interpretive Summary: Inorganic nitrate is commonly found in the environment but may be considered a major contaminant in water and soil due to excessive presence because of agricultural production practices and activities. This work present a low-cost electrical sensor constructed by screen-printing the sensor onto a biodegradable cellulose substrate. Copper nanoclusters were used to create the sensor's electrode which was combined with a specialized membrane to allow for continuous monitoring of nitrate levels in water. The sensor was shown to have a wide range of detection capability. Minimal impact, on the sensor, was found for substances which are commonly known to interfere with the detection of nitrates. Bending tests were performed on the sensor to verify mechanical durability. Additional testing was done to confirm the biodegradation of the cellulose substrate which ensures sustainability of the sensing platform.

Technical Abstract: Inorganic nitrate is ubiquitous in the environment and has become a center of attention in industrial and agricultural sectors, but it is regarded as a major contaminant in water and soil. In this work, we present a flexible, cost-effective amperometric sensor that is screen-printed on a biodegradable cellulose substrate. The sensor’s working electrode was functionalized with copper nanoclusters, followed by the application of a solid-state ion-selective membrane(ISM), enabling continuous monitoring of nitrate levels in the water. The optimized electrodeposition of copper nanoclusters served as a metal catalyst to reduce nitrate ions, while the optimized ISM cocktail selectively detected nitrate ions. The sensor showed a wide linear detection range from 1 ppm to 100 ppm with a high sensitivity of 687 nA/ppm. Selectivity tests conducted with common interfering substances such as sodium, chlorine, sulfate, bicarbonate, and nitrous dioxide) showed minimal impact on nitrate sensing. The mechanical durability of the sensor was also assessed using a customizable bending setup. Additionally, Fourier transform infrared spectroscopy (FTIR) results demonstrated the gradual degradation of the cellulose substrate into the soil, highlighting the attainment of sustainable and circular sensing capabilities.