Research Themes in my lab:

Much of the research in my group is focused on the broad area of soft condensed-matter physics. Soft materials are materials in which "the thermal fluctuations that dominate the fluid state coexist with the stringent constraints characteristic of the solid state" [Witten, Reviews of Modern Physics 71, S367 (1999)]. Well known examples include polymers, in which subunits are joined covalently to form a flexible chain, and liquid crystals, which exhibit some, but not all, of the ordering seen in solid crystals. In order to understand the structure of such materials, we employ atomic force microscopy, video microscopy, and small-angle neutron scattering. If you would like to learn more about our work, please explore some of the specific projects listed below...

Current Projects:

Alkane Crystallization

One thing we study is the crystallization of normal alkanes - paraffin wax. Although this might seem mundane at first glance, there are several reasons to study this system. More info ...

Adhesive and Mechanical Properties of Cells

Through a collaboration with research groups in Biomedical Engineering and the Medical Sciences, we are performing atomic-force microscopy studies of biological cells in order to better understand their structure, mechanical properties, and adhesive properties. More info...

PVA Hydrogels

Hydrogels are another class of soft material we are investigating. Hydrogels are typically comprised of a sparse network of cross-linked polymers imbedded in a fluid matrix - one well-known example is Jello. More info...

Mechanical Properties of Nanomaterials

The ability of the AFM to measure forces at the pico-Newton scale with nanometer lateral resolution is well suited to the study of nanomaterials such as carbon nanotubes. More info...

Atomic Force Microscopy Techniques

One of the primary experimental instruments employed in my research is the atomic force microscope (AFM), which can measure structures and forces at the nanometer and pico-Newton levels. Still only 20 years old, development of new AFM techniques continues. More info...

Web Resource: Calibration of AFM Cantilevers

An important application of the atomic force microscope is in quantitative force measurements, a prerequisite of which is accurate knowledge of the cantilever spring constant. Although several calibration methods have been described in the literature, one must often wade through numerous publications in order to track down all of the details. Here, we briefly review three popular methods and single out one — the thermal noise method — for a detailed description. More info...

Main Experimental Techniques

Optical Microscopy

Although an old technique, advances in microscopic techniques, such as phase constrast and differential interference contrast, have maintained the usefulness of this tool. An excellent primer is available on-line.

Polarizing microscope image of wax crystals
Wax crystals seen through a
polarizing optical microscope
AFM map of the centre of a spherulitic 
			polycrystalline domain

Scanning-Probe Microscopies

A much more modern microscopic method, scanning-probe microscopes allow nanometer-scale measurements of properties such as:

  • topography and adhesion forces - atomic-force microscopy (AFM)
  • electron density - scanning tunneling microscopy (STM)
  • frictional forces - lateral-force microscopy (LFM)
For an on-line introduction to these instruments, try:
AFM map of the centre of a
spherulitic multicrystalline domain

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Last updated July 16, 2005