Work

Single-Frequency Effective Capacitance Cec and Membrane Resistance Z Readout for Solid-Contact Ion-Selective Electrodes

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Here, we propose new single-frequency effective capacitance C ec and membrane resistance Z readout principle for solid-contact ion-selective electrodes (SCISEs). Conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrenesulfonate (PSS – ), i.e., PEDOT(PSS), as solid contact and valinomycin-based membrane were prepared for K + -SCISEs. At high frequencies, the membrane resistance of K + -SCISEs corresponding to impedance absolute value Z was recorded constantly as KCl aqueous solution diluted with water. The membrane resistance Z increases as the electrolyte concentration decreases. Under identical dilution steps, the linear slope of the logarithmic membrane resistance log Z vs log a K+ for K + -SCISEs with the spin-coated membrane is larger than that of the electrode covered with the drop-cast membrane. As the K + -SCISE resistance with the spin-coated membrane was reduced to hundreds of Ω, the log Z of K + -SCISEs is linearly proportional to log a K+ in the range of −1 to −3.4, providing a possibility of utilizing membrane resistance Z as a calibration-free analytical signal for SCISEs. The effective capacitance C ec of K + -SCISEs with the spin-coated membrane was performed in 0.1 M KCl applied with single frequency ranging from 1 MHz and decreases by a factor of 10 to 10 mHz. The obtained C ec of K + -SCISEs with the spin-coated membrane is linearly proportional to log f in the range of 1 MHz to 10 Hz with a slope of ca. −0.97, while at a low frequency ranging from 1 Hz to 10 mHz, the linear slope of log C ec vs log f is suppressed, where Warburg diffusion takes effect. Furthermore, the membrane resistance Z is independent of applied high frequencies, and the effective capacitance C ec is independent of the excitation amplitude.

Source: ACS Measurement Science Au

DOI: 10.1021/acsmeasuresciau.4c00093

Authors: Tingting Han, Sini Chen, Tao Song, Dongxue Han, Li Niu

Institutions: Guangzhou University, Key Laboratory of Guangdong Province, State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Sun Yat-sen University

Language: English

Topic: Analytical Chemistry and Sensors

Subfield: Bioengineering

Field: Chemical Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,500

Funders: National Natural Science Foundation of China, Guangdong Science and Technology Department, Guangzhou Municipal Science and Technology Project