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Atomic Force Microscopy

Introduction

Scanning probe microscopy (SPM) has revolutionised high resolution imaging of a wide range of samples. With the introduction of atomic force microscopy (AFM) high resolution images can be obtained without the need for the sample to be placed in a vacuum chamber. Furthermore, modern AFM systems are capable of producing high quality images of samples immersed in a wide range of liquids.

Atomic force microscope

Technical specifications

The PSIA XE-100 is a non contact atomic force microscope.

  • True non-contact mode results in improved resolution due to reduced tip and specimen damage.
  • Separated X-Y & Z Scanner. No coupling between the x-y plane and the z-scanner completely removes background curvature from the fundamental level, and effectively eliminates the cross-talk and non-linearity problems that are intrinsic to conventional piezoelectric tube based AFM systems.
  • Ultra High Force Z-Scanner. The key innovation that enables True Non-Contact Mode in the XE-Series. The ultra high force z-scanner allows a significantly higher resonance frequency than those of conventional piezoelectric tube scanners. This enables more than 10 times faster scan rates than is possible with a conventional tube type scanner.
  • Hardware Closed-loop Feedback. Hardware, not software, feedback is used to drive all the AFM signals in order to guarantee distortion free imaging. Hardware closed-loop position control allows for the absolute scaling of AFM measurements.
  • 2D Guided Flexure X-Y Scanner. High resolution imaging without background curvature. This single module parallelkinematics x-y scanner has low inertia and minimal runout, providing the best orthogonality, high responsiveness, and axis-independent performance.

The Main Unique Aspects of the Machine

  • The separated and high force nature of the scanning piezos produces very high quality images without effects of tip or sample deterioration.
  • The full enclosure and active anti-vibration table which support the instrument provide an optimal environment for high quality experimentation.
  • The dovetail head mount, magnetic tip chip carrier and in-line optical arrangement make tip positioning and laser alignment a very simple task.
  • The acquisition and analysis software is state of the art and allows detailed analysis of images and spectroscopic data.
  • A nanoindentor option enables surface hardness measurements to be undertaken.

Examples of Work undertaken at EDI

A wide variety of projects have utilised this technique for analysis of a range of surfaces. For example (left hand figure below) we have examined the surface of a compressed collagen scaffold for tissue engineering applications. The resolution of the microscope is such that it is possible to visualise the de-banding which occurs in collagen fibrils. This can be seen as the regular patterning which can be seen along the length of the fibrils running through the centre of the image.

The image on the right hand side shows the surface topography of an ion implanted titanium surface following argon ion etching. The combination of ion bean techniques has resulted in pronounced etching of the grain structure.

surface topography

For more information, please contact
Professor Jonathan Knowles
Email. j.knowles@ucl.ac.uk
Tel. +44 (0)20 3456 1189
Eastman Dental Institute
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