Nano technologies -
Method for Fabricating Arrayed Light Emitting Probes
for a Scanning Optical Microscope
Introduction
The resolution of conventional (far-field)
optical microscopes is limited by diffraction to the
wavelength of light. The shortest wavelengths are 200-300
nm. Near-field scanning optical microscopy (NSOM), a
recent advancement, obtains high-resolution images (less
than 100 nm) by working with probe light source diameters
and probe-to-surface distances shorter than the wavelength
of light.
NSOM achieves high resolution while
retaining the sensitivity and flexibility of far-field
optics, including the ability to perform fluorescence
and polarized imaging and ultraviolet, infrared, and
Raman spectroscopy. In addition, NSOM requires little
sample preparation and can be performed on a wide range
of subjects such as silicon chip matrices and living
cells. Advanced NSOM instruments also incorporate the
topographical and force data of atomic force microscopy
Commercially available NSOM probes
consist of a fiber through which light from an external
source is delivered to a tip with a 25-100 nm aperture.
The probes are still made by hand, an inefficient manufacturing
process, and the fibers are bulky, with a diameter of
80-100 micrometers. The bulkiness prevents the construction
of dense arrays of nanoscale probes that would speed
scanning and allow for simultaneous imaging with light
of different wavelengths.
Invention Description
A dense NSOM probe array has been
developed using micro-electro-mechanical systems (MEMS)
fabrication technology. Each probe in the array is also
a nanoscopic light-emitting diode (LED) configured to
emit light of a different wavelength from other probes
in the array. The LED is created by trapping nanoparticles
in a 10 nm aperture between silicon electrodes. The
inventors are now ready to integrate this array with
other silicon/MEMS functional elements, such as piezoresistive/piezoelectric
force sensors, MEMS actuators, and transistor circuitry.
Benefits
Microfabrication may provide low-cost
mass production of high-quality probes
Probe arrays will speed scanning,
enabling scanning of larger areas
Enhanced resolution
Scans with different wavelengths
of light
Integration with other MEMS devices
Features
Independent nanoscale light sources
on probe tip
Lock-in amplification of signal
Market Potential/Applications
This NSOM probe array is ready for
many research and manufacturing process applications,
including but not limited to imaging molecular semiconductor
heterostructures, laser diodes, and cell membranes;
analyzing the structure of organic thin films and polymer
blends, and drug-receptor interactions; viewing nanotubes,
quantum dots, and other nanomaterials during their synthesis
or use.
Development Stage
Lab/bench prototype completed.
IP Status
One U.S. Patent Application filed
UT Researcher
John X.J. Zhang, Ph.D, Department
of Biomedical Engineering, The University of Texas at
Austin
Kazunori Hoshino, Ph.D., Department of Biomedical Engineering,
The University of Texas at Austin
