Dielectric Relaxation Spectroscopy (DRS)


University of Nevada, Reno researcher, Nelson Publicover, of the Department of Electrical and Biomedical Engineering focusses on the development of new biosensors as well as a wide range of biomedical instrumentation and novel imaging techniques.

Technology Summary

Dielectric relaxation spectroscopy (DRS) measures the ability of a material to polarize itself within an electromagnetic field. DRS is attractive because it can probe particle properties and interactions without the use of chemically attached dies, labels, or markers. A disadvantage of current DRS techniques is the resulting interfacial polarization that occurs when the fluid/sample and electrode(s) come into contact. This restricts charge transfer and causes charge accumulation, interfering with the dielectric relaxation measurement. Current methods can require surface or system regeneration and/or recalibration (sometimes before each measurement) due to the electrode contact with the sample solution which can irreversibly interfere with DRS measurements. In the long term, this damage often requires that the sensor to be replaced.

The UNR DRS device holds a sample contained within a sample cell placed inside a holder. On either side of the sample holder, there are at least two electrodes with an alternating current source in electrical communication with at least one of the electrodes. Between the electrode and the sample cell, there is a cell barrier section partially made from an electrical insulator between then electrodes (Fig. 7). A number of particles can be added to the sample. The reaction between the particles and the sample produces a relaxation frequency between about 400 Hz and 200 kHz which is detected and measured by a detector attached to one of the electrodes.

The UNR device uses a remote electrode which can reduce or eliminate interfacial polarization effects such as charge accumulation because the electrode and sample material do not come into contact. The use of remote electrodes can reduce or eliminate surface degeneration or temporary contamination or alteration for the DRS electrodes, and can mitigate or eliminate the need to recalibrate, regenerate, or replace electrodes. Because the fluid does not touch the electrodes, sample components such as proteins or other substances sticking to the electrodes is no longer a concern.

Potential Applications

  • Sensor applications as used for:

  • National security, industrial, and military applications such as the detection of toxic chemicals, explosives, and biological agents.

  • Invasive or non-invasive medical applications (biosensors).

  • Environmental measurements (i.e. detecting substances within pipes containing fluids of interest such as ground water).

  • Terrestrial, atmospheric, and aquatic substance testing for quality control procedures (i.e. checking the purity of milk).


UNR is seeking expressions of interest from parties interested in collaborative research to further develop, evaluate, or commercialize this technology.

IP Status

UNR ID# UNR04-029
Dielectric Relaxation Spectroscopy Apparatus and Methods of Use
U.S. Patent No.: 7,514,938

Patent Information:
For Information, Contact:
Dan Langford
Technology Commercialization, Manager
University of Nevada, Reno and Desert Research Institute
Nelson Publicover
Craig Vincze