Measurement of Electric Double Layer Capacitance Using Dielectrophoresis-Based Particle Manipulation

Abstract

An electric double layer (EDL) generally exists at the interface between a conductive electrode and its adjacent liquid electrolyte. Accurate measurement of the capacitance of EDL is requisite but a great challenge due to the complexity of its variation mechanism correlated with the magnitude and frequency of applied signals and the difficulty in measuring the inner layer potentials across the EDL. Herein, a novel dielectrophoresis (DEP)-based approach is proposed to measure the capacitance of an EDL at a microelectrode/electrolyte interface. The measurement is achieved by employing DEP manipulation to micro polystyrene (PS) spheres suspended in a liquid electrolyte and determining the capacitance of EDL on the microelectrodes from the moving velocities of spheres. This method allows measurement of the capacitances of EDL under alternating current (AC) signals with different magnitudes and frequencies, so that the capacitance change with the magnitude and frequency of the applied signal can be characterized. The method avoids the impedance interference from the liquid electrolyte, external measuring systems, and other crosstalks, enabling an accurate measurement of double layer capacitance. In addition, the inner layer potentials across EDL under different magnitudes and frequencies of applied signals are comprehensively investigated, which facilitates an understanding of the ion behavior at the interfacial boundary that governs external observations of electrochemical reactions. The accurate measurement of the capacitance of EDL is of significance to explore the mechanism of interfacial functioning of electrochemical and bioelectrical devices and systems.

In Situ Nanofluid Dispersion Monitoring by Liquid–Solid Triboelectric Nanogenerator Based on Tuning the Structure of the Electric Double Layer

“…As the electric double layers of neighboring particles in the nanofluid overlap with each other, the charge transfer mechanism inside the liquid medium accordingly alters, turning out to affect the macroscopic dielectric properties of the nanofluid. [ 34 ] Moreover, the distribution of nanoparticles can also be regarded as a series of capacitances, so the relationship between the dielectric properties of the electric double layer and the particle size as well as the particles spacing can be characterized by C NP , [ 42–45 ] as illustrated in Equation (4). where C NP is the equivalent capacitance value of nanoparticle agglomerates, ε l is the dielectric constant of the liquid, R S is the geometric radius of the nanoparticles, R D is the cutoff radius of the dielectric layer that can be regarded as spacing.…”

“…As the electric double layers of neighboring particles in the nanofluid overlap with each other, the charge transfer mechanism inside the liquid medium accordingly alters, turning out to affect the macroscopic dielectric properties of the nanofluid. [34] Moreover, the distribution of nanoparticles can also be regarded as a series of capacitances, so the relationship between the dielectric properties of the electric double layer and the particle size as well as the particles spacing can be characterized by C NP , [42][43][44][45] as illustrated in Equation ( 4).…”

A Cellulose Nanofiber Capacitive Humidity Sensor with High Sensitivity and Fast Recovery Characteristics

“…At 33% RH, the CIS presents an arc shape. At this time, cations ionized from the electrolyte and H + in water molecules interacted with electrons in the metal electrode, and closely gathered near the interface to form an electric double layer (EDL) [26], which was also the reason for the high sensitivity of the sensor. With the increase in humidity, the CIS showed a quarter-circle arc on the left half and a descending arc on the right half (Figure 6c-f), which indicates the emergence of Warburg impedance (Zw).…”

Scalable two-tier protruding micro-/nano-optoelectrode arrays with hybrid optical-electrical modalities by hierarchical modular design

“…Furthermore, cyclic voltammograms reveal large charging currents for micro-/nano-optoelectrodes compared to planar electrodes due to the more extensive electric double layer (EDL) at the interface between the conductive 3D electrode and aqueous electrolyte, potentially benefiting other applications such as supercapacitors, fuel cells, electroporation devices, and dielectrophoretic devices. 24…”