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Proceedings Paper

Nanofabrication of electrochemical planar probes for single cell analysis
Author(s): R. J. Fasching; S.-J. Bai; T. Fabian; F. B. Prinz
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Paper Abstract

Needle shaped probes with a dual electrode system in submicron size have been developed for electrochemical analyses of living single cells. The probe system is designed for local probing of the cytosolic cell environment and cell organelles using amperometric, potentiometric and impedance spectroscopic methods. Silicon nitride cantilevers with an electrode metal layer system are fabricated on four-inch wafers using conventional micro fabrication techniques. The probe needle structures with a tip in sub micron scale are patterned using Focus Ion Beam (FIB) technology. A focused ion beam is utilized to write the probe needle shape into the pre-shaped cantilever and, for a dual electrode system, the probe is divided into two parts to create two separate electrodes. Subsequently, the needle structures are released from the supporting bulk silicon during a wet etching step, and a silicon nitride layer is deposited to isolate and embed the electrode metal layer. Finally, FIB milling is used for a precise exposure of the buried metal layer by cutting the top of the tip. Electrochemical characterization of nano-probes showed full functionality of Ag/AgCl as well as of platinum transducer systems. The sharpness of the probe tip with a radius of smaller than 50nm and the mechanical robustness of the needle structure allow for a reliable penetration of cell membranes. Initial measurements of cell membrane potentials and cell membrane impedances of rat fibroblast cells using Ag/AgCl transducer probes demonstrate the analytical capability of these probes in biological environments.

Paper Details

Date Published: 23 January 2006
PDF: 9 pages
Proc. SPIE 6109, Micromachining and Microfabrication Process Technology XI, 610902 (23 January 2006); doi: 10.1117/12.648950
Show Author Affiliations
R. J. Fasching, Stanford Univ. (United States)
S.-J. Bai, Stanford Univ. (United States)
T. Fabian, Stanford Univ. (United States)
F. B. Prinz, Stanford Univ. (United States)

Published in SPIE Proceedings Vol. 6109:
Micromachining and Microfabrication Process Technology XI
Mary-Ann Maher; Harold D. Stewart; Jung-Chih Chiao, Editor(s)

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