Session: 14-02-01: General Topics in MEMS and Fabrication

Paper Number: 167153

Highly Sensitive Phosphotungstic Acid-Doped Polyamide-6 Nanofibers/Sulfonated Polyether Ether Ketone Composite Membrane for Proton Exchange Membrane Fuel Cell-Based Ethanol Sensor 

This work presents the fabrication of a proton exchange membrane fuel cell (PEMFC)-based ethanol sensor, designed to provide high sensitivity, rapid response, and long-term stability for real-time ethanol detection across biomedical, industrial, and forensic applications. The sensor employs a polyamide-6 (PA6) reinforced, sulfonated polyether ether ketone (SPEEK)-based composite membrane designed for excellent proton conductivity and mechanical stability. The fabrication process begins with the cryogenic grinding of polyether ether ketone (PEEK) pellets to a fine powder, followed by sulfonation with concentrated sulfuric acid (H₂SO₄) under controlled conditions at 50°C with magnetic stirring at 1000-1250 RPM. This process optimizes the degree of sulfonation (DS), enhancing the proton conductivity of the polymer. The sulfonated SPEEK is then dissolved and functionalized with phosphotungstic acid (HPW) nanofiller to further enhance its proton transport properties. The polymer solution is coated onto UV-treated PA6 nanofibers, which serve as the base material for the sensor's proton-conducting matrix. The incorporation of the SPEEK composite into the PA6 nanofibers mat produces a hydrated matrix that raises the electrochemical efficiency of the sensor. The composite membrane is subsequently incorporated in a multi-layered sensor configuration, comprising Monel mesh electrodes. The entire assembly is then subjected to a hot-pressing process at 90°C under 2500 psi pressure to achieve strong adhesion, mechanical stability, and reproducible electrochemical performance. The sensor thus obtained is demonstrated to sense ethanol in real time with excellent sensitivity. The electrochemical analysis of the sensor reveals a faster response time, measured at under one second, and a limit of detection (LoD) set at 3.27 ppm. In addition, the sensor performs an amperometric response that is linear over a very wide range of ethanol concentrations, with a coefficient of determination (R²) of 0.9838, thus confirming its potential to measure ethanol concentrations with high accuracy. Repeatability and stability tests show no significant differences in signal response, with variations of 0.9 μA, 0.7 μA, and 0.52 μA for ethanol concentrations of 1 ppm, 40 ppm, and 100 ppm, respectively. In addition, the sensor is reproducible, as indicated by the observation that 90% of the data points are within the predefined limits of agreement in the Bland–Altman plot, thus proving to be reliable in repeated trials. One of the most critical factors for the long-term effectiveness of the sensor is the fact that the hydrated SPEEK-PA6 matrix is present, which serves to buffer environmental variations and preserve baseline stability. This arrangement guarantees that the sensor remains credible over changing environmental conditions. Characterized by its high sensitivity, quick response time, good stability, and consistency in both repeatability and reproducibility, this PEMFC-based ethanol sensor emerges as a strong candidate for large-scale, high-precision ethanol monitoring applications. Thus, this sensor’s ability to deliver consistent and accurate measurements in diverse environments makes it a valuable tool for applications in biomedical diagnostics, industrial process monitoring, and forensic analysis, where real-time ethanol detection is essential.

Presenting Author: Roy Rodriguez The University of Texas Rio Grande Valley

Presenting Author Biography: Roy Rodriguez is an undergraduate student at the University of Texas Rio Grande Valley (UTRGV), currently serving as a Student Academic Assistant at the Center for Nano Technology. His research interests span fuel cells, micro/nanofabrication, and sensor technologies. With a strong passion for advancing energy solutions and sensor applications, he actively explores innovative fabrication techniques to enhance the performance and efficiency of these systems. Roy is dedicated to gaining hands-on experience in nanotechnology and its interdisciplinary applications.

Authors:

Roy Rodriguez The University of Texas Rio Grande Valley
G M Mehedi Hossain The University of Texas Rio Grande Valley
Anthony Mendoza The University of Texas Rio Grande Valley
Fahmida Alam The University of Texas Rio Grande Valley
Karen Lozano Rice University
Ahmed Hasnain Jalal The University of Texas Rio Grande Valley