At the nanoscale, three dimensional manipulation and assembly becomes extremely challenging and also cost
prohibitive. Self-assembly provides an attractive and possibly the only highly parallel methodology to structure truly
three dimensional patterned materials and devices at this size scale for applications in electronics, optics, robotics and
medicine. This is a concise review along with a perspective of an important and exciting field in nanotechnology and is
related to a Nanoengineering Pioneer Award that I received at this SPIE symposium for my contributions to the 3D selfassembly of nanostructures. I detail a historical account of 3D self-assembly and outline important developments in this
area which is put into context with the larger research areas of 3D nanofabrication, assembly and nanomanufacturing. A
focus in this review is on our work as it relates to the self-assembly with lithographically patterned units; this approach
provides a means for heterogeneous integration of periodic, curved and angled nanostructures with precisely defined
three dimensional patterns.
Hand-held instruments capable of spectroscopic identification of chemical warfare agents (CWA) would find extensive
use in the field. Because CWA can be toxic at very low concentrations compared to typical background levels of
commonly-used compounds (flame retardants, pesticides) that are chemically similar, spectroscopic measurements have
the potential to reduce false alarms by distinguishing between dangerous and benign compounds. Unfortunately, most
true spectroscopic instruments (infrared spectrometers, mass spectrometers, and gas chromatograph-mass spectrometers)
are bench-top instruments. Surface-acoustic wave (SAW) sensors are commercially available in hand-held form, but rely
on a handful of functionalized surfaces to achieve specificity. Here, we consider the potential for a hand-held device
based on surface enhanced Raman scattering (SERS) using templated nanowires as enhancing substrates. We examine
the magnitude of enhancement generated by the nanowires and the specificity achieved in measurements of a range of
CWA simulants. We predict the ultimate sensitivity of a device based on a nanowire-based SERS core to be 1-2 orders
of magnitude greater than a comparable SAW system, with a detection limit of approximately 0.01 mg m-3.
One of the important challenges in nanoscale manufacturing is the construction of simultaneously patterned three
dimensional structures, materials and devices. Since we live in a three dimensional world, such capabilities are needed to
fully realize the capabilities of nanotechnology. We describe self-assembly processes based on utilizing intrinsic stress
and inducing grain coalescence (extrinsic stress) in thin metal films that can be used to curve or fold lithographically
patterned two dimensional (2D) panels into 3D structures. We discuss the use of intrinsic chromium (Cr) stresses and
extrinsic stresses based on induced grain coalescence in tin (Sn) based structures with varying material composition to
create a variety of lithographically patterned curved and polyhedral structures.
We report the results of scanning micro-Raman spectroscopy obtained on Au-Ag nanowires for a variety of chemical
warfare agent simulants. Rough silver segments embedded in gold nanowires showed enhancement of 105 - 107 and
allowed unique identification of 3 of 4 chemical agent simulants tested. These results suggest a promising method for
detection of compounds significant for security applications, leading to sensors that are compact and selective.
We report results of scanning micro-Raman spectroscopy obtained on isolated nanowires and networks of nanowires with different geometries and surface morphologies. We measured a strong, relatively homogeneous, surface enhancement of the Raman response from nanowires with a rough surface morphology, and detected a more sporadic enhanced response detected from smooth nanowires. These results provide the first steps towards the development of selective sensors for hazardous bio- and chemical-agent detection that rely on a combination of electronic conductance measurements and Raman spectroscopic measurements from metallic nanowire networks.
Conference Committee Involvement (12)
Biosensing and Nanomedicine XII
11 August 2019 | San Diego, California, United States
Biosensing and Nanomedicine XI
19 August 2018 | San Diego, California, United States
Biosensing and Nanomedicine X
6 August 2017 | San Diego, California, United States
Biosensing and Nanomedicine IX
28 August 2016 | San Diego, California, United States
Biosensing and Nanomedicine VIII
9 August 2015 | San Diego, California, United States
Biosensing and Nanomedicine VII
17 August 2014 | San Diego, California, United States
Biosensing and Nanomedicine III
25 August 2013 | San Diego, California, United States
Biosensing and Nanomedicine II
12 August 2012 | San Diego, California, United States
Biosensing and Nanomedicine
21 August 2011 | San Diego, California, United States
Biosensing III
1 August 2010 | San Diego, California, United States
Biosensing II
4 August 2009 | San Diego, California, United States
Biosensing
12 August 2008 | San Diego, California, United States
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