Parylene C coated microelectrodes for scanning electrochemical microscopy

Abstract

a b s t r a c tHerein, we present a simple microelectrode preparation methodology consisting in coating a platinum wire or a carbon fiber with a thin insulating Parylene C film (e.g. 1-10 m), to produce SECM probes with a small and constant probe RG (i.e. ratio between the radius of the insulating sheath and the radius of the active electrode area). After exposition of a fresh active electrode area by blade cutting, a disc shaped electrode is obtained thanks to a protective hot mounting wax layer that avoids Parylene C coating deformation and is easily removed with acetone. Stiffness and straightness of the probe can be tuned by modifying the Parylene C coating thickness and the length of the carbon fiber or platinum wire. This simple electrode preparation method is highly reproducible (c.a. > 90%). The prepared Parylene C coated microelectrodes were characterized by optical microscopy, cyclic voltammetry, scanning electrochemical microscopy (SECM) approach curves and finally applied to SECM imaging of Pt band structures in contactless and contact mode.

High‐Performance Graphene‐Fiber‐Based Neural Recording Microelectrodes

“…Parylene-C was selected due to its high dielectric property, biocompatibility, pin-hole free and uniform coatings, and its common use for neural prostheses. [41] Microelectrodes made from bare graphene microfiber (i.e., no Pt coating) were fabricated for comparison (Figure S3). Moreover, while the polymer coating process increased the robustness of the graphene microfibers, the flexibility was also improved as demonstrated by tying an overhand knot (Movie 1 and Figure S4).…”

3D Electrodes for Bioelectronics

“…Conformal Parylene film is a good insulator on 3D electrodes, and it can be easily patterned by O 2 plasma etching. [115,116,[118][119][120] Due to these characteristics, Parylene can be applied as an insulation layer on entire devices, [116,119,121] or as a substrate of free-standing 3D probes. [79,117,122,123] Figure 7b shows an SEM image of a microelectrode coated with Parylene-C. [124] Ghame-Motlagh et al reported that Parylene-C were deposited using a chemical vapor deposition process and etched by oxygen plasma from the tips.…”

Oxygen Absorption in Electrocatalyst Layers Detected by Scanning Electrochemical Microscopy

“…To equilibrate the chemical potentials of oxygen in the solution and across the interface, oxygen partitioning takes place and additional oxygen is supplied from across the interface, or from within the porous interface. For example, an oxygen partition induced positive feedback is observed when approaching a liquid‐air interface, [31] a water‐air interface,[ 32 , 33 ] or an interface with a porous hydrophobic film. [1] In these cases, the positive feedback is not due to the electrochemical reaction on an electrochemically active substrate, but positive feedback due to the availability and partitioning of the additional oxygen for equilibrating the chemical potentials of the oxygen in the solution and across the interface.…”