Surface or interfacial impedance spectroscopy has been
established as a powerful technique for many applications, ranging from
electrochemistry and corrosion analysis to biochips and biosensors. Most
applications utilize a single or an array of electrodes and an electrical
instrument to perform impedance measurement and analysis, which does not have
imaging capability. Atomic force microscopy has been used to probe local
capacitance, but it is impractical for routine analysis because it is slow and
complicated. It is highly desired to image or map the local impedance of the
entire surface of an electrode, which so far has not been demonstrated.
In an important development at ASU, researchers have
invented a method which allows the imaging of surface impedance in real time. In
addition, it also allows the monitoring of molecular binding processes without
using labels, which is particularly useful for biochips and biosensors. Finally,
the technique can provide information about the charge of biomolecules adsorbed
on a sensor surface, which provides additional insight into the functions of the
molecules. The basic principle of the technique relies on the sensitive
dependence of surface plasmon resonance (SPR) on local surface charge density.
By applying a potential modulation to an electrode surface, it is possible to
obtain an image of the DC component and the amplitude and phase images of the AC
component. This allows a new dimension of imaging that is currently not possible
with conventional SPR techniques.
Potential Applications
This technology will facilitate the imaging of surface
impedance in solution, which will be important to researchers working in the
following fields:
- Biochips
- Biosensors
- Drug discovery
- Diagnostics
- Electro analysis
Benefits and Advantages
- Fast: Interface images can be generated in real time
- Novel: This technique is reported to be the first that
can image the local impedance of an entire electrode surface.
- Better Contrast: This technique will reveal interface
features that are not possible with conventional SPR imaging techniques.
- Ease of Use: Allows the monitoring of molecular binding
processes without using labels.
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For more information about the inventor(s) and their
research, please see
Dr. Tao's
directory webpage
Dr. Tao's laboratory
webpage
Dr.
Tao's Biodesign directory webpage
