Super-resolution Scanning Electrochemical Microscopy.

To achieve super-resolution scanning electrochemical microscopy (SECM), we must overcome the theoretical limitation associated with noncontact electrochemical imaging of surface-generated species. This is the requirement for mass transfer to the electrode, which gives rise to the diffusional broadening of surface features. In this work, a procedure is developed for overcoming this limitation and thus generating "super-resolved" images using point spread function (PSF)-based deconvolution, where the point conductor plays the same role as the point emitter in optical imaging. In contrast to previous efforts in SECM towards this goal, our method uses a finite element model to generate a pair of corresponding blurred and sharp images for PSF estimation, avoiding the need to perform parameter optimization for effective deconvolution. It can therefore be used for retroactive data treatment and an enhanced understanding of the structure-property relationships that SECM provides.

Evaluating the Use of Edge Detection in Extracting Feature Size from Scanning Electrochemical Microscopy Images.

The edge of a reactive or topographical feature is hard to estimate from feedback-based scanning electrochemical microscopy due to diffusional blurring, but is crucial to determining the accurate size and shape of these features. In this work, numerical simulations are used to demonstrate that the inflection point in a 1D line scan corresponds well to the true feature edge. This approach is then applied in 2D using the Canny algorithm to experimental images of two model substrates and a biological sample. This approach circumvents the need for aligning the imaged region between separate microscopy techniques, reveals hidden details embedded in SECM images, and allows individual features to be separated from their background more effectively.

Simultaneous Electrochemical and Emission Monitoring of Electrogenerated Chemiluminescence through Instrument Hyphenation.

One of the long-standing challenges to performing electrogenerated chemiluminescence (ECL) research is the need for dedicated instrumentation or highly customized cells to achieve reproducibility. This manuscript describes an approach to designing ECL systems through the hyphenation of existing laboratory instruments, which provide innate time correlation of electrochemical and emission data. This design methodology lowers the entry barrier required to obtaining reproducible ECL measurements and provides flexibility in the scope of applications. Uniquely, the simplicity of this system's experimental interface, a spectrochemical quartz cuvette, readily enables collaboration with finite element modeling that simulates ECL occurring in the cuvette-based cell. This combination of empirical and simulation data allowed for the investigation of the intertwined kinetics behind the coreactant ECL mechanism of tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)32+) and tripropylamine (TPA). The complexity of the system measurable via the hyphenation methodology was further scaled though the addition of tris[2-(4,6-difluorophenyl)pyridinato-C2, N] iridium(III) (Ir(dFppy)3) and the observation of real time multiplexing.

Altered Spatial Resolution of Scanning Electrochemical Microscopy Induced by Multifunctional Dual-Barrel Microelectrodes.

The nonuniform diffusion profile to the edge of many multifunctional microelectrodes has the potential to give rise to distortions in its imaging capability, reducing the spatial accuracy of the techniques they are used in. In this work, numerical simulations are used to predict these distortions for dual-barrel electrodes used in the combined feedback/generation-collection mode of scanning electrochemical microscopy imaging a model substrate. The sensitivity of this distortion to tip-substrate distance, electrolyte composition, and size and shape of a reactive substrate feature are discussed.