12 research outputs found
Reproducible Deep-UV SERRS on Aluminum Nanovoids
Surface-enhanced Raman scattering
(SERS) with deep-UV excitation
is of particular interest because a large variety of biomolecules
such as amino acids exhibit electronic transitions in the UV spectral
range and resonant excitation dramatically increases the cross section
of the associated vibrational modes. Despite its potential, UV-SERS
is still little-explored. We present a novel straightforward scalable
route to fabricate aluminum nanovoids for reproducible SERS in the
deep-UV without the need of expensive lithographic techniques. We
adopt a modified template stripping method utilizing a soluble template
and self-assembled polymer spheres to create nanopatterned aluminum
films. We observe high surface enhancement of approximately 6 orders
of magnitude, with excitation in the deep-UV (244 nm) on structures
optimized for this wavelength. This work thus enables sensitive detection
of organics and biomolecules, normally nonresonant at visible wavelengths,
with deep-UV surface-enhanced resonant Raman scattering on reproducible
and scalable substrates
Quantitative SERS Using the Sequestration of Small Molecules Inside Precise Plasmonic Nanoconstructs
We show how the macrocyclic host, cucurbit[8]uril (CB[8]),
creates
precise subnanometer junctions between gold nanoparticles while its
cavity simultaneously traps small molecules; this enables their reproducible
surface-enhanced Raman spectroscopy (SERS) detection. Explicit shifts
in the SERS frequencies of CB[8] on complexation with guest molecules
provides a direct strategy for absolute quantification of a range
of molecules down to 10<sup>–11</sup> M levels. This provides
a new analytical paradigm for quantitative SERS of small molecules
In Situ SERS Monitoring of Photochemistry within a Nanojunction Reactor
We demonstrate a powerful SERS-nanoreactor
concept composed of
self-assembled gold nanoparticles (AuNP) linked by the sub-nm macrocycle
cucurbit[<i>n</i>]uril (CB[<i>n</i>]). The CB[<i>n</i>] functions simultaneously as a nanoscale reaction vessel,
sequestering and templating a photoreaction within, and also as a
powerful SERS-transducer through the large field enhancements generated
within the nanojunctions that CB[<i>n</i>]s define. Through
the enhanced Raman fingerprint, the real-time SERS-monitoring of a
prototypical stilbene photoreaction is demonstrated. By choosing the
appropriate CB[<i>n</i>] nanoreactor, selective photoisomerism
or photodimerization is monitored in situ from within the AuNP-CB[<i>n</i>] nanogap
Mapping Atomic-Scale Metal–Molecule Interactions: Salient Feature Extraction through Autoencoding of Vibrational Spectroscopy Data
Atomic-scale features, such as step edges and adatoms,
play key
roles in metal–molecule interactions and are critically important
in heterogeneous catalysis, molecular electronics, and sensing applications.
However, the small size and often transient nature of atomic-scale
structures make studying such interactions challenging. Here, by combining
single-molecule surface-enhanced Raman spectroscopy with machine learning,
spectra are extracted of perturbed molecules, revealing the formation
dynamics of adatoms in gold and palladium metal surfaces. This provides
unique insight into atomic-scale processes, allowing us to resolve
where such metallic protrusions form and how they interact with nearby
molecules. Our technique paves the way to tailor metal–molecule
interactions on an atomic level and assists in rational heterogeneous
catalyst design
Controllable Multimodal Actuation in Fully Printed Ultrathin Micro-Patterned Electrochemical Actuators
Submillimeter or micrometer scale electrically controlled
soft
actuators have immense potential in microrobotics, haptics, and biomedical
applications. However, the fabrication of miniaturized and micropatterned
open-air soft actuators has remained challenging. In this study, we
demonstrate the microfabrication of trilayer electrochemical actuators
(ECAs) through aerosol jet printing (AJP), a rapid prototyping method
with a 10 μm lateral resolution. We make fully printed 1000
× 5000 × 12 μm3 ultrathin ECAs, each of
which comprises a Nafion electrolyte layer sandwiched between two
poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)
electrode layers. The ECAs actuate due to the electric-field-driven
migration of hydrated protons. Due to the thinness that gives rise
to a low proton transport length and a low flexural rigidity, the
printed ECAs can operate under low voltages (∼0.5 V) and have
a relatively fast response (∼seconds). We print all the components
of an actuator that consists of two individually controlled submillimeter
segments and demonstrate its multimodal actuation. The convenience,
versatility, rapidity, and low cost of our microfabrication strategy
promise future developments in integrating arrays of intricately patterned
individually controlled soft microactuators on compact stretchable
electronic circuits
Controllable Multimodal Actuation in Fully Printed Ultrathin Micro-Patterned Electrochemical Actuators
Submillimeter or micrometer scale electrically controlled
soft
actuators have immense potential in microrobotics, haptics, and biomedical
applications. However, the fabrication of miniaturized and micropatterned
open-air soft actuators has remained challenging. In this study, we
demonstrate the microfabrication of trilayer electrochemical actuators
(ECAs) through aerosol jet printing (AJP), a rapid prototyping method
with a 10 μm lateral resolution. We make fully printed 1000
× 5000 × 12 μm3 ultrathin ECAs, each of
which comprises a Nafion electrolyte layer sandwiched between two
poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)
electrode layers. The ECAs actuate due to the electric-field-driven
migration of hydrated protons. Due to the thinness that gives rise
to a low proton transport length and a low flexural rigidity, the
printed ECAs can operate under low voltages (∼0.5 V) and have
a relatively fast response (∼seconds). We print all the components
of an actuator that consists of two individually controlled submillimeter
segments and demonstrate its multimodal actuation. The convenience,
versatility, rapidity, and low cost of our microfabrication strategy
promise future developments in integrating arrays of intricately patterned
individually controlled soft microactuators on compact stretchable
electronic circuits
Controllable Multimodal Actuation in Fully Printed Ultrathin Micro-Patterned Electrochemical Actuators
Submillimeter or micrometer scale electrically controlled
soft
actuators have immense potential in microrobotics, haptics, and biomedical
applications. However, the fabrication of miniaturized and micropatterned
open-air soft actuators has remained challenging. In this study, we
demonstrate the microfabrication of trilayer electrochemical actuators
(ECAs) through aerosol jet printing (AJP), a rapid prototyping method
with a 10 μm lateral resolution. We make fully printed 1000
× 5000 × 12 μm3 ultrathin ECAs, each of
which comprises a Nafion electrolyte layer sandwiched between two
poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)
electrode layers. The ECAs actuate due to the electric-field-driven
migration of hydrated protons. Due to the thinness that gives rise
to a low proton transport length and a low flexural rigidity, the
printed ECAs can operate under low voltages (∼0.5 V) and have
a relatively fast response (∼seconds). We print all the components
of an actuator that consists of two individually controlled submillimeter
segments and demonstrate its multimodal actuation. The convenience,
versatility, rapidity, and low cost of our microfabrication strategy
promise future developments in integrating arrays of intricately patterned
individually controlled soft microactuators on compact stretchable
electronic circuits
Controllable Multimodal Actuation in Fully Printed Ultrathin Micro-Patterned Electrochemical Actuators
Submillimeter or micrometer scale electrically controlled
soft
actuators have immense potential in microrobotics, haptics, and biomedical
applications. However, the fabrication of miniaturized and micropatterned
open-air soft actuators has remained challenging. In this study, we
demonstrate the microfabrication of trilayer electrochemical actuators
(ECAs) through aerosol jet printing (AJP), a rapid prototyping method
with a 10 μm lateral resolution. We make fully printed 1000
× 5000 × 12 μm3 ultrathin ECAs, each of
which comprises a Nafion electrolyte layer sandwiched between two
poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)
electrode layers. The ECAs actuate due to the electric-field-driven
migration of hydrated protons. Due to the thinness that gives rise
to a low proton transport length and a low flexural rigidity, the
printed ECAs can operate under low voltages (∼0.5 V) and have
a relatively fast response (∼seconds). We print all the components
of an actuator that consists of two individually controlled submillimeter
segments and demonstrate its multimodal actuation. The convenience,
versatility, rapidity, and low cost of our microfabrication strategy
promise future developments in integrating arrays of intricately patterned
individually controlled soft microactuators on compact stretchable
electronic circuits
Accurate Transfer of Individual Nanoparticles onto Single Photonic Nanostructures
Controlled integration
of metallic nanoparticles (NPs) onto photonic
nanostructures enables the realization of complex devices for extreme
light confinement and enhanced light–matter interaction. For
instance, such NPs could be massively integrated on metal plates to
build nanoparticle-on-mirror (NPoM) nanocavities or photonic integrated
waveguides (WGs) to build WG-driven nanoantennas. However, metallic
NPs are usually deposited via drop-casting, which prevents their accurate
positioning. Here, we present a methodology for precise transfer and
positioning of individual NPs onto different photonic nanostructures.
Our method is based on soft lithography printing that employs elastomeric
stamp-assisted transfer of individual NPs onto a single nanostructure.
It can also parallel imprint many individual NPs with high throughput
and accuracy in a single step. Raman spectroscopy confirms enhanced
light–matter interactions in the resulting NPoM-based nanophotonic
devices. Our method mixes top-down and bottom-up nanofabrication techniques and shows the potential of building complex
photonic nanodevices for multiple applications ranging from enhanced
sensing and spectroscopy to signal processing
Gap-Dependent Coupling of Ag–Au Nanoparticle Heterodimers Using DNA Origami-Based Self-Assembly
We
fabricate heterocomponent dimers built from a single 40 nm gold
and a single 40 nm silver nanoparticle separated by sub-5 nm gaps.
Successful assembly mediated by a specialized DNA origami platform
is verified by scanning electron microscopy and energy-dispersive
X-ray characterization. Dark-field optical scattering on individual
dimers is consistent with computational simulations. Direct plasmonic
coupling between each nanoparticle is observed in both experiment
and theory only for these small gap sizes, as it requires the silver
dipolar mode energy to drop below the energy of the gold interband
transitions. A new interparticle-spacing-dependent coupling model
for heterodimers is thus required. Such Janus-like nanoparticle constructs
available from DNA-mediated assembly provide an effective tool for
controlling symmetry breaking in collective plasmon modes