Microscopy Characterization of Nanoporous Alumina
George
National Aeronautics and Space Administration
1
Glasgow ,
1Department
Jessica
2
Koehne ,
Adam
3
Seger
,Olufisayo
1
Jejelowo ,
Nader
3
Pourmand ,
M.
2
Meyyappan
of biology Texas Southern University, 2NASA Ames Research Center, 3University of Santa Cruz Baskin School of Engineering
Abstract
Background
Nanoporous alumina is a thin oxide film,
which is fabricated from 99.99%
aluminum that is anodized in an acidic
electrolyte solution. Nanoporous alumina
is a nanomaterial that has gained
significant attention from many biologist
because of its ion conducting pores,
which can be used to detect biological
molecules.
Materials and methods
 Nanoporous
Alumina
substrate
(figure 1) is the main specimen.
 Reagents were acid, base and water
were used to soak alumina substrate.
 Hitachi TM-1000 scanning microscope
(figure .2) was used for the observation
and characterization of the nanoporous
alumina substrate before and after the
reagents and protein was applied.
 Hitachi S-4800 (figure 3) scanning
microscope was used for observation at
a higher resolution.
Results
Nanoporous alumina is being characterized with a scanning electron
microscope (SEM) to study environmental effects on the thin-film material.
The experiment will evaluate the size and distribution of pores in the
nanoporous alumina. A unique characteristic of nanoporous alumina is its
nanochannels (of 50nm to 300 nm in diameter) that can transmit particles
and conduct ionic current. The ion current can be used as a signal in
biosensing, but the signal depends on pore size and distribution. Currently,
the effects of time, solvent, and heat on alumina nanopore properties are
unknown. Environmental effects on the nanoporous alumina pores size will
be evaluated in this experiment. A scanning electron microscope is used to
characterize a nanoporous alumina surface and determine the pore size.
The nanoporous alumina will be placed in various environments, such as air,
water, and ethanol for various periods of time to evaluate pore stability.
Results from the electron microscopy analysis will be compared with surfacecontact angle measurements of the material. The experiment results will
determine whether pores are stable under a variety of conditions, and what
factors contribute to their degradation or blockage. These results will enable
future studies of nanoporous alumina as a platform for nanoporous
biosensors.
Scanning Electron Microscope
Raster scanning is utilized by a scanning electron microscope (SEM) to
produce an image of a specimen by detecting secondary electrons. Then,
images are captured digitally and displayed on a computer monitor and
stored on a computer’s hard disk.
Initial Alumina
substrate
untreated
10 μm
10 μm
Alumina
substrate treated
with H₂O for
Alumina
24hrs.
substrate
treated with
NaOH for
24hrs.
10 μm
Alumina
substrate
treated with
HCl for 24hrs.
10 μm
The initial untreated alumina substrate had an average pore
diameter of 209 nm and a standard deviation of 24.10 nm.
Alumina substrate treated with NaOH for 24hrs had an
average pore diameter of 205.38 nm and a standard deviation
of 19.24 nm
Conclusion
(figure 2) TM-1000
scanning electron
microscope has a
maximum resolution of
100 nm and a
maximum magnification
of 10k .
(Figure 1) Nanoporous
Alumina substrate is an
excellent sample for observation
with a SEM to observe its
porous characteristics.
Image of porous
Alumina taken by
TM-1000 SEM at
maximum
magnification of
10K
10 μm
H₂O HCl
NaOH
100ml 0.1 M
0.1M
Scanning Electron Microscope (SEM)
Future Work
(figure. 3). An S4800 SEM has a
maximum
resolution of 1 nm.
The max zoom
for an S-4800
SEM is 800k.
The spatial arrangement of the porous alumina was
characterized and determined. The characterization and
observation of nanoporous alumina placed in chemical
solutions, such as H2O, NaOH and HCl was essential for
supplying useful information about nanoporous alumina. The
information gathered from this experiment will be valuable to
biologist for finding ways to use nanoporous alumina as a
biosensor for detecting biomolecules.
Determine the change in pore diameter for nanoporous
alumina substrates soaked for 24hrs in H₂O and HCl.
Image of porous
Alumina taken by
S-4800 SEM at
magnification of
40K .
Acknowledgements
500 nm
I would like to give thanks to everyone who aided with the
completion of this project for their dedication and devotion.
References
J. W. Diggle, T. C. Downie and C. W. Goulding, Chem. Rev., 1969, 69, 365.
Schmid.Gunter, The Royal Society of Chemistry., 2002, 1231.
Template provided by: “posters4research.com”