A proton-selective membrane (PSM)-deposited dual-gate ion-sensitive field-effect transistor (DG-ISFET) integrating a microchamber-embedded filter membrane for bacterial enrichment and antimicrobial susceptibility test

Abstract

The antimicrobial susceptibility test (AST) is one of the most common methods to evaluate bloodstream infections (BSI). Currently, AST methods usually required prolonged sample preparation processes and bulky systems, making it difficult to provide timely information for clinical decisions. In this paper, we integrated a proton-selective membrane (PSM)-deposited dual-gate ion-sensitive field-effect transistor (DG-ISFET) with a microchamber-embedded filter membrane to perform bacterial enrichment and incubation followed by on-chip AST. The DG-ISFET sensor consists of a high-k dielectric hafnium oxide (HfO2) sensing surface and dual gate, enabling high ion sensitivity, and low drifting and hysteresis issues. By depositing a PSM on DG-ISFET, the sensor has higher proton sensitivity and selectivity, preventing interference from other ion signals in the bacterial culture medium. To further shorten the bacterial culture time, we integrated a microchamber-embedded filter membrane on top of the DG-ISFET sensor to enrich the amount of bacteria and place seeded bacteria close to DG-ISFET’s sensing surface. As a proof of concept, we first evaluated the proton sensitivity and selectivity of DG-ISFET under various PSM deposition thicknesses. Then, we demonstrated that the PSM-deposited DG-ISFET system can successfully distinguish kanamycin-susceptible and resistant Escherichia coli strains treated with various kanamycin concentrations in 30 min based on the continuous drain-source current (Ids) pattern. We envision that this fully integrated system can perform rapid, real-time, continuous AST, which can potentially be applied in resource-limited environments or point-of-care settings.