US 6,621,079 B1Granted

Apparatus and method for a near field scanning optical microscope in aqueous solution

AssigneeUniversity of Virginia Patent Foundation

InventorsZhifeng Shao, Gabor Szabo, Anders Mannelqvist

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Abstract

The present invention near field scanning optical microscope NSOM, and related method thereof, provides a high resolution image of a sample in aqueous solution without damaging the sample. This attribute will greatly expand the applications and utility of a NSOM in biomedicine, among other fields. Moreover, the NSOM can be further extended to include signals other than light. In operation, a pipette is filled with an electrolyte solution (aqueous solution) and lowered through the reservoir toward the surface of the sample while the current between the electrode inside the pipette and the electrode in the reservoir is monitored. As the tip of the pipette approaches the surface, the ion current decreases because the space through which ions can flow is reduced. The pipette is then scanned laterally over the surface and the path of the tip pipette follows the topography of the surface. An optical image is simultaneously provided as the light source is incident on the sample and the emitted light reaches the image acquisition device after being transmitted through the sample. The acquisition device converts the light energy into electrical signals where they are processed for displaying the acquired images on the monitor or printer.

Claims15

Dependent claims

A near field scanning optical microscope (NSOM) comprising:

a reservoir holding a sample to be scanned therein;
a pipette having an open tip communicating with a hollow shaft;
an electrolyte solution disposed within the reservoir covering the sample and disposed within the tip of said pipette;
a first electrode disposed in said shaft in ionic communication with said electrolyte solution in said open tip, said first electrode being in ionic communication with electrolyte solution in said reservoir via said open tip by means of electrolyte solution within said tip;
a second electrode disposed in said reservoir in ionic communication with said electrolyte solution in said reservoir and forming a continuous ionic current path between said first and second electrodes via the electrolyte solution in said reservoir and in said open tip;
scanning means for scanning said tip of said pipette over a top surface of said sample in a scanning pattern;
voltage means for applying a voltage across said first and second electrodes;
current means for measuring a current flowing in the ionic current path between said first and second electrodes through said open tip of said pipette and for supplying an indication of said current at an output thereof;
and
control logic means having an output connected to said scanning means and an input connected to said output of said current means for causing said scanning means to set the height of said tip at a desired distance above said top surface;
wherein the improvement comprises:
a light source disposed on said microscope for emitting light through said shaft of said pipette and onto the sample;
said hollow shaft being opaque to substantially prevent light emitted from said light source from being transmitted through the walls of said shaft;
and
an image acquisition means in optical communication with said light source so that the sample is in optical communication between said light source and said image acquisition means, whereby said image acquisition means for acquiring an image of the sample.

12 more elements

A method for optically imaging a sample comprising the steps of:

disposing the sample to be scanned in a reservoir containing an electrolyte covering the sample;
providing a pipette having an open tip communicating with a hollow shaft, wherein said shaft is at least partially opaque;
disposing an electrolyte within the tip of the pipette;
disposing a first electrode in the shaft in ionic communication with the electrolyte in the open tip;
disposing a second electrode in the reservoir in ionic communication with the electrolyte in said reservoir and forming a continuous ionic current path between said first and second electrodes via the electrolyte solution in said reservoir and in said open tip;
applying a voltage across the first and second electrodes and measuring an ionic current flowing in the ionic current path between the first and second electrodes through the open tip;
scanning the tip of the pipette over a top surface of the sample in a scanning pattern with the tip of the pipette at a desired distance above the top surface which will maintain the current flow between the first and second electrodes through the open tip at a constant value which will cause the tip to follow the top surface in close non-contacting proximity thereto so as to provide a z-directional component of the position of the tip of the pipette;
scanning the tip of the pipette over a top surface of the sample in a scanning pattern with the tip of the pipette in a plane parallel and close adjacent above the top surface;
emitting light through said shaft of said pipette onto the sample;
and
acquiring light having been transmitted through the sample for acquiring an image of the sample and outputting a corresponding acquisition signal.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/606,343Filed 29 Jun 2000 · us provisional application
Priority: 2 Jul 1999
Granted: 16 Sep 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

G01Q 60/44
Particular types of SPM [Scanning Probe Microscopy] or microscopes; Essential components thereof: sICM [Scanning Ion-Conductance Microscopy] or…
G01Q 60/22
SNOM [Scanning Near-Field Optical Microscopy] or apparatus therefor, e.g. SNOM probes: probes, their manufacture, or their related…
G01Q
Scanning-probe techniques or apparatus