Laser-pulled ultramicroelectrodes

This section discusses the fabrication of microelectrodes with diameters of a few micrometers to tens of nanometers using a laser-pulled technique. The methods discussed focus on the fabrication of platinum (Pt) ultramicroelectrodes (UMEs) sealed in 

Buehler, Lake Bluff, IL) a method to manipulate the plane of the polishing surface and a microscope or other method to facilitate viewing the UME tip. An optical microscope is a necessity for monitoring the various stages of pulled UME construction. 

Optimization of a pulling program requires patience, practice, and a bit of luck. The efficiency of UME fabrication using this technique is rarely more than 60% and when every step is taken into consideration, is typically mnch less. Under ideal conditions, one capiUary should produce two identical microelectrodes. However, small imbalances in the pulling solenoids or imprecise calibration of the laser scanning results in less than ideal behavior. 

Filament number corresponding to the scan length and scan speed of the laser for the 

Heat Smaller tip longer taper Larger tip shorter taper  

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B. Preparation and electrochemical response of 1-3 mn Pt disk electrodes. Anal. Chem. 2009, 81, 5496-5502. (g) Laforge, F. O., Velmumgan, J., Wang, Y, Mirkin, M. V. Nanoscale imaging of surface topography and reactivity with the scanning electrochemical microscope. Anal. Chem. 2009, 81, 3143-3150. (h) MauzeroU, J., LeSuer, R. J. Laser-pulled ultramicroelectrodes. In Handbook of Electrochemistry,... 

Amicro-liquid/liquid (p-L/L) interface is usually formed either at the tip of a pulled glass micropipet or within a small hole made in a thin membrane (8, 91, 92). Unlike solid ultramicroelectrodes (UMEs), such pipets or holes are easily made. Pipets as small as a few nanometer radii have recently been fabricated using a laser puller (93). Dual-pipets (or d-pipets) can also be prepared by pulling 0-glass tubing (94-96). Another simple way of producing a p-L/L interface in a microcavity is to chemically dissolve microwire encapsulated within a glass tube (97). 

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