Copper Fluoride Doped Polypyrrole for Portable and Enhanced Ammonia Sensing at Room Temperature

Point-of-care (POC) monitoring of breath ammonia has emerged as a great approach for non-invasive chronic kidney disease (CKD) diagnosis. Polypyrrole (PPy) is recognized as a suitable polymer material for breath ammonia sensing. Here we describe the copper fluoride (CuF2) doping effect on sensing performance of the ammonia gas sensor based on PPy. At first, PPy was synthesized by chemical oxidative polymerization and characterized by scanning electron microscopy, energy dispersive X-ray analysis, and Fourier Transform Infrared Spectroscopy techniques. The CuF2 was doped to the polymer by an aqueous ion exchange process. A portable sensing system was developed for portable ammonia detection by measuring the resistance variation of the fabricated electrode from synthesized materials. The gas-sensing results disclose that the CuF2-PPy based sensor displays the highest response to 2 ppm NH3, which is 3 times higher than that of the pure PPy sensor. The low limit of detection (LOD) value for pure PPy was found to be 0.19 ppm, which has been decreased to 0.02 ppm for CuF2 doped PPy. The CuF2-PPy resistive sensor exhibits a sustainable, selective, and stable sensing response to ammonia even in the presence of 60 % humidity. Moreover, the fabricated setup is low-cost, user-friendly, and suitable enough to be used at the point of care and CKD diagnosis applications.

Automated summary

Point-of-care monitoring of breath ammonia for non-invasive CKD diagnosis using a CuF2-doped PPy gas sensor has demonstrated high sensitivity and low detection limits. The sensor exhibited a strong response to 2 ppm NH3, with a detection limit decreased to 0.02 ppm after CuF2 doping. Additionally, the sensor displayed sustained, selective, and stable sensing response to ammonia, even in high humidity conditions.