Electronic Circuit Simulations as a Tool to Understand Distorted Signals in Single-Entity Electrochemistry

Abstract

Electrochemical analysis relies on precise measurement of electrical signals, yet the distortions caused by potentiostat circuitry and filtering are rarely addressed. Elucidation of these effects is essential for gaining insights behind sensitive low-current and short-duration electrochemical signals, e.g., in single-entity electrochemistry. We present a simulation approach utilizing the Electrical Simulation Program with Integrated Circuit Emphasis (SPICE), which is extensively used in electronic circuit simulations. As a proof-of-concept, we develop a universal electrical circuit model for single nanoparticle impact experiments, incorporating potentiostat and electronic filter circuitry. Considering these alterations, the experimentally observed transients of silver nanoparticle oxidation were consistently shorter and differently shaped than those predicted by established models. This reveals the existence of additional processes, e.g., migration, partial or asymmetric oxidation. These results highlight the SPICE approach's ability to provide valuable insights into processes occurring during single-entity electrochemistry, which can be applied to various electrochemical experiments, where signal distortions are inevitable.

Recent Developments in Single-Entity Electrochemistry

“…252−254 Aside from simulating single particle motion, a recent study utilized Electrical Simulation Program with Integrated Circuit Emphasis (SPICE), which is historically used in electronic circuit simulations, to understand and predict signal distortions in single particle collision (Figure 9). 255 Unlike Monte Carlo simulations and random walk models, which are simulated at the level of physical particles, this approach developed an equivalent circuit model to simulate nanoparticle impacts, which is shown in Figure 9a. The switching on and off of two parallel circuits generates dynamic changes of charge transfer resistance and double-layer capacitance of the nanoparticle to the working electrode, which mimic the events of nanoparticle collision.…”

“…SEE measurements are often experimentally challenging with current magnitudes in the low picoampere range and temporal responses at the (sub)­millisecond time scale required. Therefore, successful SEE experiments rely on the measurement of low signals with the best time resolution. ,, A longstanding challenge in this regard is signal distortion due to the analog or digital low-pass filters which are commonly required to mitigate noise. − Moreover, instrumental limitations could compromise signal characteristics, such as amplitude or duration. − As a result, a true electrochemical characteristic of a transient single particle/molecule event, free from instrumental convolution, is often unrealizable from raw data . To reveal the original signal due only to the SEE collision, simulation approaches have been applied. ,,, For instance, dynamic Monte Carlo simulations have been used to discern multiple distinct motion trajectories of individual Ag nanoparticle collisions from time-resolved current traces .…”

“… 250 − 254 Moreover, instrumental limitations could compromise signal characteristics, such as amplitude or duration. 253 − 255 As a result, a true electrochemical characteristic of a transient single particle/molecule event, free from instrumental convolution, is often unrealizable from raw data. 254 To reveal the original signal due only to the SEE collision, simulation approaches have been applied.…”

Electrochemical Analysis of Attoliter Water Droplets in Organic Solutions through Partitioning Equilibrium

“…Single-entity electrochemistry has recently attracted significant interest [ 1 , 2 , 3 ]. In particular, a single entity has been electrochemically monitored individually to study its characteristics, such as metal nanoparticles [ 4 , 5 ], biomaterials [ 6 ], nanobubbles [ 7 ], liquid droplets [ 8 ], and vesicles [ 9 ].…”

Detection of Single Ag–Cu2O Particle Collision and Catalysis Using Impact Electrochemistry

“…This method, which focuses on single-entity electrochemistry detection, has garnered significant attention, particularly for its ability to unveil electrochemical processes taking place at the nanoparticle level during collisions with the working electrode. Impact electrochemistry, leveraging ultramicroelectrodes (UME), has proven instrumental in detecting a diverse range of redox electrocatalytic reactions. − In the field of single-particle detection, various types of synthetic and biological micro- and nanoswimmers act as mobile probes, efficiently exploring microscopic environments to locate and interact with electrodes. − The different morphologies and structure (e.g., porous) of microparticles play an important role in single-particle electrochemical detection due to its inherent benefits. The porous structure offers increased surface area compared to solid counterparts of equivalent size, creating more sites for interaction between the analyte and the electrode and enhancing the sensitivity of the detection process. , Porous structures provide a higher density of active sites on the electrode surface, with better electrocatalytic activity essential for many electrochemical detection methods .…”