Flexible Screen-Printed Carbon-Based Electrode Functionalized With Multiwall Carbon Nanotubes for Portable Point-of-Care pH Sensing

Flexible, screen-printed electrode (SPE) systems offer significant advantages in biomedical applications due to their rapid fabrication capability and adaptability to irregular surfaces. Despite this, no flexible, screen-printed biosensors for pH measurement are readily available on the market. This article introduces an innovative fabrication technique for integrating flexible SPE systems with multiwall carbon nanotubes (MWCNTs). These SPE systems feature flexible screen-printed working electrodes (WEs) functionalized with MWCNTs (f-MWCNTs) for pH sensing, achieving a fabrication success rate of 78.57%. Furthermore, these SPE systems have been optimized to improve voltage changes and thoroughly characterized for performance using pH buffer solutions. This was done utilizing open-circuit potentiometry. The results demonstrate that the SPE systems can detect pH ranges from 4.0 to 8.9 with an average sensitivity of 33.66 mV/pH, an output range of 202.62 mV, a settling time of 19.71 s, and stability for up to 72 h. Additionally, the SPE systems have been tested with artificial saliva in the pH range of 5.0–8.3, achieving a sensitivity of 44.86 mV/pH and an output range of 192.90 mV. These findings pave the way for further exploration in pH sensing research, particularly utilizing SPE systems coated with MWCNTs.