High-Speed, High-Resolution Impedance Sensor

Tech ID: 10272 / UC Case 2003-344-0


While there has been extensive work in developing radio-frequency probes for measuring proximal impedances in air, these probes have been limited to applications using good conductors as their proximal impedance source. For electrolytic and biological samples, lower frequency probes have generally been employed, but they are limited to a relatively low signal-to-noise ratio and slow signal response due to the stray capacitances and large resistances often encountered in such samples.


A University of California researcher has invented a radio-frequency probe that is suitable for use with electrolytic and biological samples, providing a time resolution on the order of 10-9 seconds and a spatial resolution in the range of 10 nm to 1 mm.


The UC probe could be used to make quantitative measurements and images of the electrical impedances of samples of metals, semiconductors, insulators, electrolytic fluids over a wide range of frequencies (100 to 109 Hz) when in close proximity to them. The UC probe will likely be used in both fixed and scanning-type applications either as a standalone device, or as a part of a surface-probe microscope (SPM) tip as in atomic force microscopy (allowing simultaneous measurement of local electrical impedance and surface topology) or as an element within an array of probes that cover a wide variety of electrical and chemical conditions. The high speed and resolution of the UC probe will make it the preferred impedance sensor in many applications.


The UC impedance probe:

  • has unparalleled temporal and spatial resolution;
  • is compatible with a wide variety of samples, including dynamic biological systems; and
  • can be used in conjunction with other sensor technologies, such as the topography sensing of SPM.

Patent Status

Country Type Number Dated Case
United States Of America Issued Patent 7,451,646 11/18/2008 2003-344


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  • Cleland, Andrew N.
  • Soh, Hyongsok T.

Other Information


indmicroscopy, indpharma

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