Pressure-resistant and portable array gas membrane device for rapid Escherichia coli detection in infant milk powder via smartphone colorimetry with all-in-one preparation strategy

This study presents a novel Pressure-Resistant and Portable Array Gas Membrane Separation (PAGMS) device for the rapid, smartphone-based detection of Escherichia coli ( E. coli ) in infant milk powder. The PAGMS device efficiently separates acetic acid, a byproduct of E. coli growth, enhancing detection sensitivity. Utilizing bromocresol violet as an indicator, this method quantifies E. coli based on colorimetric changes, with UV spectrum absorbance shifts indicating a linear correlation (R 2 = 0.9864) within 5.0–120 μmol/L acetic acid concentration. Visual MINTEQ simulations validate the mechanism behind the indicator’s response. The approach surpasses traditional plate culture methods in terms of sample preparation time, achieving detection within a comparable timeframe of 15 min, and can concurrently process up to 48 samples, thereby substantially enhancing analytical throughput while detecting E. coli with a limit of detection of 5 cfu/g. This method demonstrates enhanced sensitivity, speed, and high-throughput capabilities, offering significant advantages in food safety monitoring.