Application notes 5 min read

SECM height relief with OSP: an application in sensors – Scanning Probes – Application Note 3

Latest updated: May 6, 2020

Abstract

The response of the Scanning Electrochemical Microscope (SECM) depends on the surface conductivity of the sample as well as its topography, or more precisely the distance between the probe and the sample. In some cases where the sample is uneven or too rough, the change of response due to the topography is higher the change of response due to conductivity. Measurements in constant distance mode are then needed.
M370/M470 systems provide a way of performing constant distance measurements. First, the sample is scanned using the Optical Surface Profiler (OSP) technique, a laser-based profilometer. Second, the topography data are used in the SECM measurement to keep the probe at a constant distance from the sample. The note shows the procedure to do these measurements on a screen-printed sensor.

 

Introduction

Application of the scanning electrochemical microscopy (SECM) technique to sensors or electrodes can provide valuable information. Providing a high-resolution view of the sensor’s activity or conductivity across the surface of the sensor can help the development of higher sensitivity sensors with greater reproducibility. Key to the measurement of electrochemical activity using the SECM technique is the ability to maintain the SECM electrode in close and constant proximity to the surface during a scan as the current measured across a surface can be influenced by the topography and the electrochemical activity, producing a response that is a sum of both. This may not be an issue for small areas, or for sensors that could be considered flat, however, for the sensors that: are not flat (e.g. screen-printed), cannot be levelled (e.g. delicate biological interface) or not precisely enough (e.g. large area
sensors), have some masking or underlying tracking, it may be necessary to remove the topology effect from the probe’s signal to access the true electrochemical activity over the surface.
With the addition of Height-Tracking, it is possible to effectively remove the effects of topography resulting in an unbiased measure of the electrochemical activity. In this application note the topography measurement is obtained using the OSP (Optical Sensor Profiler).

To view the entire application note please click the download button below.

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