3 research outputs found
Protein-Based Electronic Skin Akin to Biological Tissues
Human skin provides an interface
that transduces external stimuli into electrical signals for communication
with the brain. There has been considerable effort to produce soft,
flexible, and stretchable electronic skin (E-skin) devices. However,
common polymers cannot imitate human skin perfectly due to their poor
biocompatibility, biofunctionality, and permeability to many chemicals
and biomolecules. Herein, we report on highly flexible, stretchable,
conformal, molecule-permeable, and skin-adhering E-skins that combine
a metallic nanowire (NW) network and silk protein hydrogel. The silk
protein hydrogels offer high stretchability and stability under hydration
through the addition of Ca<sup>2+</sup> ions and glycerol. The NW
electrodes exhibit stable operation when subjected to large deformations
and hydration. Meanwhile, the hydrogel window provides water and biomolecules
to the electrodes (communication between the environment and the electrode).
These favorable characteristics allow the E-skin to be capable of
sensing strain, electrochemical, and electrophysiological signals
High-Contrast Infrared Absorption Spectroscopy via Mass-Produced Coaxial Zero-Mode Resonators with Sub-10 nm Gaps
We
present a wafer-scale array of resonant coaxial nanoapertures
as a practical platform for surface-enhanced infrared absorption spectroscopy
(SEIRA). Coaxial nanoapertures with sub-10 nm gaps are fabricated
via photolithography, atomic layer deposition of a sacrificial Al<sub>2</sub>O<sub>3</sub> layer to define the nanogaps, and planarization
via glancing-angle ion milling. At the zeroth-order Fabry-Pérot
resonance condition, our coaxial apertures act as a “zero-mode
resonator (ZMR)”, efficiently funneling as much as 34% of incident
infrared (IR) light along 10 nm annular gaps. After removing Al<sub>2</sub>O<sub>3</sub> in the gaps and inserting silk protein, we can
couple the intense optical fields of the annular nanogap into the
vibrational modes of protein molecules. From 7 nm gap ZMR devices
coated with a 5 nm thick silk protein film, we observe high-contrast
IR absorbance signals drastically suppressing 58% of the transmitted
light and infer a strong IR absorption enhancement factor of 10<sup>4</sup>∼10<sup>5</sup>. These single nanometer gap ZMR devices
can be mass-produced via batch processing and offer promising routes
for broad applications of SEIRA
High-Contrast Infrared Absorption Spectroscopy via Mass-Produced Coaxial Zero-Mode Resonators with Sub-10 nm Gaps
We
present a wafer-scale array of resonant coaxial nanoapertures
as a practical platform for surface-enhanced infrared absorption spectroscopy
(SEIRA). Coaxial nanoapertures with sub-10 nm gaps are fabricated
via photolithography, atomic layer deposition of a sacrificial Al<sub>2</sub>O<sub>3</sub> layer to define the nanogaps, and planarization
via glancing-angle ion milling. At the zeroth-order Fabry-Pérot
resonance condition, our coaxial apertures act as a “zero-mode
resonator (ZMR)”, efficiently funneling as much as 34% of incident
infrared (IR) light along 10 nm annular gaps. After removing Al<sub>2</sub>O<sub>3</sub> in the gaps and inserting silk protein, we can
couple the intense optical fields of the annular nanogap into the
vibrational modes of protein molecules. From 7 nm gap ZMR devices
coated with a 5 nm thick silk protein film, we observe high-contrast
IR absorbance signals drastically suppressing 58% of the transmitted
light and infer a strong IR absorption enhancement factor of 10<sup>4</sup>∼10<sup>5</sup>. These single nanometer gap ZMR devices
can be mass-produced via batch processing and offer promising routes
for broad applications of SEIRA