Parallel Imaging and Template‐Free Patterning of Self‐Assembled Monolayers with Soft Linear Microelectrode Arrays

Abstract

Reagents were generated locally on an array of eight individually addressable electrodes in order to modify self‐assembled monolayers. Since the array was manufactured in a soft polymer material, it can have mechanical contact with a delicate sample without inducing defects. Lengthy leveling procedures are not necessary and the scan times can be shortened.

High-throughput scanning electrochemical microscopy brushing of strongly tilted and curved surfaces

“…Soft linear arrays of carbon microelectrodes were prepared as described previously [50,51,53]. In brief, microchannels (midpointto-midpoint distance 500 m) were UV laser-ablated (193 nm ArF excimer laser; fluence = 250-350 mJ; frequency = 50 Hz; Lambda Physik, Göttingen, Germany) through a metallic mask into the PET film and manually filled with the carbon ink.…”

“…After curing for one hour at 80 • C, the conductive carbon tracks were covered and sealed with a thin Parylene C coating of 3-5 m thickness. The cross-section was exposed either by UV laser ablation or by razor blade cutting and defines sickle-shaped active electrode areas [50,51,53]. The quality of the electrodes and the shape of the exposed area were inspected using a laser scanning microscope Keyence VK 8700 (Keyence, Osaka, Japan).…”

“…Up to 32 working electrodes can be controlled individually vs. one reference electrode (RE) and one auxiliary electrode (AX) using the in-house made software SECMx [53]. A Pt wire was used as AX and an Ag wire served as quasi-RE to which all potentials given herein are referred to.…”

“…Even initially dry surfaces can be scanned if the mediator solution is provided and removed by means of microfluidics integrated into the probe [52]. Delicate surfaces such as self-assembled monolayers have been brushed without damaging them due to a very small mechanical pressure exerted by the probes on the surface [49,53]. Since the amperometric current response in SECM relies on the diffusional mass transport of the redox-active species with a time constant ≈ r T 2 ·D −1 , where r T is the radius of the UME and D is the diffusion coefficient of the redox species, probe translation rates faster than 25 m·s −1 have to be avoided in order to achieve an appropriate resolution and to exclude convectional disturbances [54].…”

“…industrial applications and quality testing). For this purpose, we have recently presented different soft linear arrays of microelectrodes as SECM probes [49,50,53,55]. Earlier approaches for SECM multi-tips were also reported, such as the two-dimensional imaging of O 2 , H 2 O 2 and glucose distributions by an array of 400 individually addressable Pt microelectrodes by Meyer et al [56], the linear independent 16 Pt microelectrode array from Barker et al [57] and the Au multinanotip electrode from Deiss et al [58]; however, in contrast to the soft probe arrays, the earlier developed approaches do not combine a constant working distance mode with individually addressable sensors for high-throughput reactivity imaging and surface modification.…”