Characterization of Microfabricated Probes for Combined Atomic Force and High-Resolution Scanning Electrochemical Microscopy

A combined atomic force and scanning electrochemical microscope probe is presented. The probe is electrically insulated except at the very apex of the tip, which has a radius of curvature in the range of 10-15 nm. Steady-state cyclic voltammetry measurements for the reduction of Ru(NH3) 6Cl3 and feedback experiments showed a distinct and reproducible response of the electrode. These experimental results agreed with finite element simulations for the corresponding diffusion process. Sequentially topographical and electrochemical studies of Pt lines deposited onto Si 3N4 and spaced 100 nm apart (edge to edge) showed a lateral electrochemical resolution of 10 nm. © 2006 American Chemical Society

Assessment of insulated conductive cantilevers for biology and electrochemistry

This paper describes the characterization and application of electrically insulated conductive tips mounted on a cantilever for use in an atomic force microscope and operated in liquid. These multifunctional probes were microfabricated and designed for measurements on biological samples in buffer solution, but they can also be employed for electrochemical applications, in particular scanning electrochemical microscopy. The silicon nitride based cantilevers had a spring constant ≤0.1 N m-1 and a conductive tip, which was insulated except at the apex. The conductive core of the tip consisted of a metal, e.g. platinum silicide, and exhibited a typical radius of 15 nm. The mechanical and electrical characterization of the probe is presented and discussed. First measurements on the hexagonally packed intermediate layer of Deinococcus radiodurans demonstrated the possibility to adjust the image contrast by applying a voltage between a support and the conductive tip and to measure variations of less than 1 pA in faradaic current with a lateral resolution of 7.8 nm. © 2005 IOP Publishing Ltd

Development of Insulated Conductive Probes with Platinum Silicide Tips for Atomic Force Microscopy in Cell Biology

A microfabrication process of a multifunctional probe is introduced for atomic force microscopy and various electrochemical measurements on biological samples in buffer solution. The silicon nitride probes have a spring constant lower than 0.1 N/m and a conductive tip, which is tightly insulated except at the apex. The conductive core of the tip consists of PtxSi y and shows a typical radius of curvature of 15 nm. A simultaneous measurement of topography and electrical current on graphite in air was demonstrated

Surface characterization using atomic force microscopy (AFM) in liquid environments

Liquid imaging provides intrinsic advantages for AFM experiments, particularly for conducting in situ studies of chemical or biochemical reactions. Using liquid media has benefits for improving resolution, since the amount of force applied between the tip and sample can be reduced. Surface changes caused by immersion in different liquids can be investigated, such as for studying electrochemical reactions with different parameters of solvent polarity, pH or ion concentration. Aqueous buffers enable studies of biochemical reactions that simulate physiological conditions, with time-lapse capture of image frames at different intervals. Studies of surface changes throughout the course of self-assembly reactions have been monitored with AFM in liquid media. By injecting new molecules into the sample cell, AFM-based nanofabrication can be accomplished by nanografting protocols. Liquid environments expand the capabilities for scanning probe studies to provide insight for dynamic processes at the molecular-level. © Springer-Verlag Berlin Heidelberg 2013