Other

Veeco Instruments Inc.

Lucien P Ghislain

Virgil B Elings

Watt W Webb

A sensor includes a sensor head with at least two surfaces separated by a gap. One surface is mechanically fixed, a second surface is free to move and deflections of the second surface relative to the first surface are monitored by optical interferometry. An optical fiber could be used to direct light from a light source to the sensor and collect light reflected by the sensor. Interaction of molecules or other objects in the sample with the second surface is detected as a change in amplitude and/or phase of deflection the second surface in response to an applied driving signal. A layer of binding molecules may be immobilized on the second surface and this surface exposed to a sample.

Sensor apparatus and method using optical interferometry

A sensor apparatus and method includes a sensor head with at least two surfaces separated by a gap. One surface is mechanically fixed, a second surface is free to move and deflections of the second surface relative to the first surface are monitored by optical interferometry. In one embodiment, an optical fiber is used to direct light from a light source to the sensor and collect light reflected by the sensor. In alternate embodiments the sensor apparatus includes integrated optical elements, free-space optics, and direct laser-diode sensing. In operation, interaction of molecules or other objects in the sample with the second surface is detected as a change in amplitude and/or phase of deflection the second surface in response to an applied driving signal. A layer of binding molecules may be immobilized on the second surface and this surface exposed to a sample. The invention includes a method for detecting an analyte in a sample, including detecting the presence of analyte, the amount of analyte or the rate of association and/or dissociation of the analyte with a binding partner.

A method of scanning probe microscopy includes using a cantilever having a planar body, generally opposed first and second ends, and a tip disposed generally adjacent the second end and extending downwardly towards a surface of a sample. Preferably, the sample is disposed on a support surface. The method includes directing a beam of light onto the second end in a direction substantially parallel to the support surface. In operation, the second end directs the beam towards a detector apparatus at a particular angle. Then, the method monitors a change in the angle of deflection of the beam of light caused by deflection of the cantilever as the cantilever tip traverses the surface of the sample, the change being indicative of a characteristic of the surface. Preferably, the second end includes a flat reflective surface, with the flat reflective surface being generally non-planar with respect to the planar body of the cantilever. In addition, the flat reflective surface comprises a mirror fixed to the second end, while in another embodiment, the flat reflective surface is microfabricated integrally with the cantilever.

Method and apparatus for atomic force microscopy

A scanning probe microscope uses a high refractive index solid immersion lens (SIL) probe to provide optical images with a resolution better than the diffraction limit in air. The SIL probe has a spherical upper surface and a conical (or pyramidal) lower surface with a sharp tip. The SIL reduces the focused spot size because the spherical surface increases the angle of the marginal rays and the high refractive index material shortens the wavelength. The focused spot generates an evanescent wave having an amplitude that decays exponentially with distance from the SIL. The sharp tip on the lower surface reduces the tip-sample contact area and the tip-sample separation so that sample is within the near-field of the SIL probe. The sample perturbs the evanescent wave and a photodetector monitors characteristics of the light. A cantilever carries the SIL probe and a cantilever deflection sensor permits precise control of tip-sample forces and separation. The cantilever deflection sensor operates in a force feedback loop to maintain the tip-sample gap within the near-field as the SIL probe scans over the sample in a raster pattern to generate optical data.

Scanning probe optical microscope using a solid immersion lens

A scanning force microscope utilizes a probe consisting of a glass stylus, or probe, positioned and oriented by an optical trap. The probe is an optically transparent cylinder having at least one tip on its axis with an apex dimension less than one wavelength of the light used for the trap. An optical displacement sensor utilizing forward scatter or an optical interferometer detects the motion of the probe caused by the force between the tip and an object to be scanned. Mutual scanning displacement between the probe and the object is carried out by moving a support stage along x/y coordinates or by movement of the light beam forming the optical trap along these coordinates. Radiation forces due to the three-dimensional intensity distribution of the light in the optical trap allow the probe to be positioned with precise control and with a low spring constant, allowing resolution in the range of .lambda./100, with the probe being capable of measuring forces smaller than 0.1 pN.

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Millbrae, CA, United States of America

Lucien P Ghislain