Reply to the ‘Comment on “Electron-interfered field-effect transistors as a sensing platform for detecting a delicate surface chemical reaction”’ by M. Micjan and M. Weis, J. Mater. Chem. C, 2026, 14, DOI: 10.1039/D5TC02689J

Abstract

Michal Micjan and Martin Weis argue that electron-interfered FET (EIFET) cannot detect surface reactions via threshold-voltage shifts (ΔV_th) because charge produced at the interference electrode (IE) must manifest primarily as a gate current (I_G); they further suggest that the reported V_th dynamics arise from bias-stress and interfacial trapping rather than chemistry at the IE. We rebut these claims on three grounds. First, a capacitive-network analysis shows that the transient displacement current, I_G, is quantitatively and operationally negligible, while the quasi-static V_th modulation is the only relevant observable. Charge transiently accumulated at the IE modulates the effective gate bias through capacitive coupling and produces a measurable, reversible V_th(t) signal. Second, the characteristic V_th(t) signature co-varies with an independent surface-science observable—the IE surface energy γ_s(t)—and survives stringent controls (dielectric substitution, solvent/ionic solutions, and preformed SAMs) that a trap-only hypothesis cannot explain. Third, the magnitude and time scale of ΔV_th are quantitatively consistent with small, transient IE charge densities (10¹¹–10¹² cm⁻²), far below monolayer coverages and fully compatible with the proposed mechanism.