Instrumentation and metrology for nanomechanics
An important tool in nanotechnology, the atomic force microscope
measures forces precisely yet without good accuracy. We developed a
method that quickly calibrates the normal spring constant of the
cantilevers used to
measure forces in AFM to an accuracy of 10%. We also developed a method
to quantitatively measure lateral forces. Other progress lies in
tip-radius calibration, the use of optical excitation at the tip-sample
interface, and the influence of higher modes of the cantilever on its
response. Here are links for programs for tip-radius and
[Refs. 32-37, 40, 44, 47, 48 in journal list.]
Topography and device performance
microsensors, "MEMS", can be fabricated with moving devices that
can make contact with the substrate upon which they are grown. Their
are coated with a molecular layer that lowers the likelihood
sticking and thus prevents failure of the device, but the contribution
roughness to the "stiction" remains poorly understood. Using the tip of
an AFM to replace one side of the silicon-oxide interface, we are
correlating the properties of the interface with stiction. Likewise,
topography changes the capacitance of self-assembled monolayer devices.
[Refs. 38, 40, 41, 45 in journal and Refs. 12, 13 in proceedings list.]
of tissue-growth substrates and asphalt binders
only the chemical environment, but also the topographic and mechanical
of cells influence their growth into tissues. Using an AFM, which
applies displacements on the order of that cells themselves create, we
have characterized the topographic properties of implants and are
deciphering the mechanical properties of polyacrylimide gels.
Similarly, the binder that holds roads together is visco-elastic, and
we have started investigating its properties on the nanoscale.
39 in journal list.]
Mechanical response of molecules
We have investigated how molecules -- from the vital to the virulent --
respond to excitation: hemoglobin to carbon dioxide and
nanotubes to shear, bacteriorhodopsin to light, and liquid crystals and
[Ref. 42, 43, 46 in
Nanoscience and society
are technologies that have not been well accepted by the public, for
example, vaccines, nuclear power, and genetically modified foods. The
public is currently generally content with
nanotechnology, although people balk at the thought of injecting
"nanobots" into their bodies. We found six factors that increase the
confidence of WPI students in their acceptance of new medicines.
Watching a video on nanotechnology can change its acceptance by the
viewers. (For the references used for the 2007-08 video, please read
p.31 of the 2007-08 report.) Acceptance of nanotechnology rises as the
self-reported knowledge of surveyees rises. There is possible
environmental risk when nanosilver particles are released into water,
yet it is possible to make guidelines to mitigate the threat.
Report 2004-05... Report 2005-06... Report
2006-07... Video 07-08...
2009-10... Poster 2009-10...
Last modified: January 2013