10 research outputs found
Electroless Copper Plating of Inkjet-Printed Polydopamine Nanoparticles: a Facile Method to Fabricate Highly Conductive Patterns at Near Room Temperature
Aqueous dispersions of artificially
synthesized, mussel-inspired polyÂ(dopamine) nanoparticles were inkjet
printed on flexible polyethylene terephthalate (PET) substrates. Narrow
line patterns (4 Îźm in width) of polyÂ(dopamine) resulted due
to evaporatively driven transport (coffee ring effect). The printed
patterns were metallized via a site-selective Cu electroless plating
process at a controlled temperature (30 °C) for varied bath times.
The lowest electrical resistivity value of the plated Cu lines was
about 6 times greater than the bulk resistivity of Cu. This process
presents an industrially viable way to fabricate Cu conductive fine
patterns for flexible electronics at low temperature, low cost, and
without need of sophisticated equipment
Flexible-to-Stretchable Mechanical and Electrical Interconnects
Stretchable electronic devices that
maintain electrical
function
when subjected to stress or strain are useful for enabling new applications
for electronics, such as wearable devices, humanâmachine interfaces,
and components for soft robotics. Powering and communicating with
these devices is a challenge. NFC (near-field communication) coils
solve this challenge but only work efficiently when they are in close
proximity to the device. Alternatively, electrical signals and power
can arrive via physical connections between the stretchable device
and an external source, such as a battery. The ability to create a
robust physical and electrical connection between mechanically disparate
components may enable new types of hybrid devices in which at least
a portion is stretchable or deformable, such as hinges. This paper
presents a simple method to make mechanical and electrical connections
between elastomeric conductors and flexible (or rigid) conductors.
The adhesion at the interface between these disparate materials arises
from surface chemistry that forms strong covalent bonds. The utilization
of liquid metals as the conductor provides stretchable interconnects
between stretchable and non-stretchable electrical traces. The liquid
metal can be printed or injected into vias to create interconnects.
We characterized the mechanical and electrical properties of these
hybrid devices to demonstrate the concept and identify geometric design
criteria to maximize mechanical strength. The work here provides a
simple and general strategy for creating mechanical and electrical
connections that may find use in a variety of stretchable and soft
electronic devices
Flexible-to-Stretchable Mechanical and Electrical Interconnects
Stretchable electronic devices that
maintain electrical
function
when subjected to stress or strain are useful for enabling new applications
for electronics, such as wearable devices, humanâmachine interfaces,
and components for soft robotics. Powering and communicating with
these devices is a challenge. NFC (near-field communication) coils
solve this challenge but only work efficiently when they are in close
proximity to the device. Alternatively, electrical signals and power
can arrive via physical connections between the stretchable device
and an external source, such as a battery. The ability to create a
robust physical and electrical connection between mechanically disparate
components may enable new types of hybrid devices in which at least
a portion is stretchable or deformable, such as hinges. This paper
presents a simple method to make mechanical and electrical connections
between elastomeric conductors and flexible (or rigid) conductors.
The adhesion at the interface between these disparate materials arises
from surface chemistry that forms strong covalent bonds. The utilization
of liquid metals as the conductor provides stretchable interconnects
between stretchable and non-stretchable electrical traces. The liquid
metal can be printed or injected into vias to create interconnects.
We characterized the mechanical and electrical properties of these
hybrid devices to demonstrate the concept and identify geometric design
criteria to maximize mechanical strength. The work here provides a
simple and general strategy for creating mechanical and electrical
connections that may find use in a variety of stretchable and soft
electronic devices
Flexible-to-Stretchable Mechanical and Electrical Interconnects
Stretchable electronic devices that
maintain electrical
function
when subjected to stress or strain are useful for enabling new applications
for electronics, such as wearable devices, humanâmachine interfaces,
and components for soft robotics. Powering and communicating with
these devices is a challenge. NFC (near-field communication) coils
solve this challenge but only work efficiently when they are in close
proximity to the device. Alternatively, electrical signals and power
can arrive via physical connections between the stretchable device
and an external source, such as a battery. The ability to create a
robust physical and electrical connection between mechanically disparate
components may enable new types of hybrid devices in which at least
a portion is stretchable or deformable, such as hinges. This paper
presents a simple method to make mechanical and electrical connections
between elastomeric conductors and flexible (or rigid) conductors.
The adhesion at the interface between these disparate materials arises
from surface chemistry that forms strong covalent bonds. The utilization
of liquid metals as the conductor provides stretchable interconnects
between stretchable and non-stretchable electrical traces. The liquid
metal can be printed or injected into vias to create interconnects.
We characterized the mechanical and electrical properties of these
hybrid devices to demonstrate the concept and identify geometric design
criteria to maximize mechanical strength. The work here provides a
simple and general strategy for creating mechanical and electrical
connections that may find use in a variety of stretchable and soft
electronic devices
Effect of Yttrium-Incorporated TiO<sub>2</sub> Electron Transport Layer on the Photovoltaic Performance of Triple-Cation Perovskite Solar Cells
Achieving an excellent electron transport layer is significant
for high-performance perovskite solar cells. A TiO2 compact
film is extensively applied as an electron transport layer. However,
some limiting issues, such as unfavorable band offset, unsatisfactory
electrical conductivity, low electron mobility, and high-density defects,
remain in the TiO2 electron transport layer. In this work,
yttrium (Y) is proposed as a dopant in the TiO2 electron
transport layer. It is revealed that the incorporation of Y promotes
the Fermi energy level of TiO2 shift upward, bringing about
more favorable energy-level alignment for the transport of photogenerated
carriers. In addition, the device assembled with a Y-TiO2 electron transport layer exhibits an increased built-in potential,
suggesting a more powerful driving force for charge separation and
transport. Eventually, the triple-cation perovskite solar cell equipped
with a Y-TiO2 electron transport layer acquires an efficiency
of 20.09%. It is superior to that of the TiO2-based device
(17.28%). The results indicate that Y-ion doping is a promising method
to fabricate highly efficient perovskite solar cells
Regulation of the Deposition Morphology of Inkjet-Printed Crystalline Materials via Polydopamine Functional Coatings for Highly Uniform and Electrically Conductive Patterns
We report a method to achieve highly
uniform inkjet-printed silver nitrate (AgNO<sub>3</sub>) and a reactive
silver precursor patterns on rigid and flexible substrates functionalized
with polydopamine (PDA) coatings. The printed AgNO<sub>3</sub> patterns
on PDA-coated substrates (glass and polyethylene terephthalate (PET))
exhibit a narrow thickness distribution ranging between 0.9 and 1
Îźm in the line transverse direction and uniform deposition profiles
in the line axial direction. The deposited reactive silver precursor
patterns on PDA-functionalized substrates also show âdome-shapedâ
morphology without âedge-thickenedâ structure due to
âcoffee-stainâ effect. We posit that the highly uniform
functional ink deposits formed on PDA-coated substrates are attributable
to the strong binding interaction between the abundant catecholamine
moieties at the PDA surface and the metallic silver cations (Ag<sup>+</sup> or AgÂ(NH<sub>3</sub>)<sup>2+</sup>) in the solutal inks.
During printing of the ink rivulet and solvent evaporation, the substrateâliquid
ink (SâL) interface is enriched with the silver-based cations
and a solidification at the S/L interface is induced. The preferential
solidification initiated at the SâL interface is further verified
by the in situ visualization of the dynamic solidification process
during solvent evaporation, and results suggest an enhanced crystal
nucleation and growth localized at the SâL interface on PDA
functionalized substrates. This interfacial interaction mediates solute
transport in the liquid phase, resulting in the controlled enrichment
of solute at the SâL interface and mitigated solute precipitation
in both the contact line region and the liquid inkâvapor (LâV)
interface due to evaporation. This mediated transport contributes
to the final uniform solid deposition for both types of ink systems.
This technique provides a complementary strategy for achieving highly
uniform inkjet-printed crystalline structures, and can serve as an
innovative foundation for high-precision additive delivery of functional
materials
Flexible-to-Stretchable Mechanical and Electrical Interconnects
Stretchable electronic devices that
maintain electrical
function
when subjected to stress or strain are useful for enabling new applications
for electronics, such as wearable devices, humanâmachine interfaces,
and components for soft robotics. Powering and communicating with
these devices is a challenge. NFC (near-field communication) coils
solve this challenge but only work efficiently when they are in close
proximity to the device. Alternatively, electrical signals and power
can arrive via physical connections between the stretchable device
and an external source, such as a battery. The ability to create a
robust physical and electrical connection between mechanically disparate
components may enable new types of hybrid devices in which at least
a portion is stretchable or deformable, such as hinges. This paper
presents a simple method to make mechanical and electrical connections
between elastomeric conductors and flexible (or rigid) conductors.
The adhesion at the interface between these disparate materials arises
from surface chemistry that forms strong covalent bonds. The utilization
of liquid metals as the conductor provides stretchable interconnects
between stretchable and non-stretchable electrical traces. The liquid
metal can be printed or injected into vias to create interconnects.
We characterized the mechanical and electrical properties of these
hybrid devices to demonstrate the concept and identify geometric design
criteria to maximize mechanical strength. The work here provides a
simple and general strategy for creating mechanical and electrical
connections that may find use in a variety of stretchable and soft
electronic devices
Fabrication of Novel Transparent Touch Sensing Device via Drop-on-Demand Inkjet Printing Technique
A novel
transparent touch sensor was fabricated with a drop-on-demand
inkjet printing technique on borosilicate glass and flexible polyethylene
terephthalate (PET) substrates. Conductive polyÂ(3,4-ethylenedioxythiophene):polyÂ(styrenesulfonate)
(PEDOT:PSS) and dielectric polyÂ(methylsiloxane) were deposited on
a desired area to form a capacitive touch sensor structure. The properties
of the printed sensors (optical transparency, electrical resistance
and touch sensing performance) were investigated with varying PEDOT:
PSS printing passes. A novel transparent touch sensor fabricated with
an all-inkjet-printing method is demonstrated for the first time.
This process holds industrially viable potential to fabricate transparent
touch sensors with an inkjet printing technique on both rigid and
flexible substrates for a wide range of applications
Regenerable Fluorescent Nanosensors for Monitoring and Recovering Metal Ions Based on Photoactivatable Monolayer Self-Assembly and HostâGuest Interactions
Efficient
detection, removal, and recovery of heavy metal ions from aqueous
environments represents a technologically challenging and ecologically
urgent question in the face of increasing metal-related pollution
and poisoning across the globe. Although small-molecule and entrapment-based
nanoparticle sensors have been extensively explored for metal detection,
neither of these extant strategies satisfies the critical needs for
high-performance sensors that are inexpensive, efficient, and recyclable.
Here we first report the development of a regenerable fluorescent
nanosensor system for the selective and sensitive detection of multiple
heavy metal ions, based on light-switchable monolayer self-assembly
and hostâguest interactions. The system exploits photocontrolled
inclusion and exclusion responses of an Îą-cyclodextrin (CD)-containing
surface conjugated with photoisomerizable azobenzene as a supramolecular
system that undergoes reversible assembly and disassembly. The metal
nanosensors can be facilely fabricated and photochemically switched
between three chemically distinct entities, each having an excellent
capacity for selective detecting specific metal ions (namely, Cu<sup>2+</sup>, Fe<sup>3+</sup>, Hg<sup>2+</sup>) in a chemical system
and in assays on actual water samples with interfering contaminants
Silicones for Stretchable and Durable Soft Devices: Beyond Sylgard-184
This paper identifies and characterizes
silicone elastomers that
are well-suited for fabricating highly stretchable and tear-resistant
devices that require interfacial bonding by plasma or UV ozone treatment.
The ability to bond two or more pieces of molded silicone is important
for creating microfluidic channels, chambers for pneumatically driven
soft robotics, and other soft and stretchable devices. Sylgard-184
is a popular silicone, particularly for microfluidic applications.
However, its low elongation at break (âź100% strain) and moderate
tear strength (âź3 N/mm) make it unsuitable for emerging, mechanically
demanding applications of silicone. In contrast, commercial silicones,
such as Dragon Skin, have excellent mechanical properties yet are
difficult to plasma-bond, likely because of the presence of silicone
oils that soften the network yet migrate to the surface and interfere
with plasma bonding. We found that extracting silicone oligomers from
these soft networks allows these materials to bond but only when the
Shore hardness exceeds a value of 15 A. It is also possible to mix
highly stretchable silicones (Dragon Skin and Ecoflex) with Sylgard-184
to create silicones with intermediate mechanical properties; interestingly,
these blends also only bond when the hardness exceeds 15 A. Eight
different Pt-cured silicones were also screened; again, only those
with Shore hardness above 15 A plasma-bond. The most promising silicones
from this study are Sylgard-186 and Elastosil-M4130 and M4630, which
exhibit a large deformation (>200% elongation at break), high tear
strength (>12 N/mm), and strong plasma bonding. To illustrate the
utility of these silicones, we created stretchable electrodes by injecting
a liquid metal into microchannels created using such silicones, which
may find use in soft robotics, electronic skin, and stretchable energy
storage devices