16 research outputs found
Microfluidic Behavior of Alumina Nanotube-Based Pathways within Hydrophobic CNT Barriers
Printed Stretchable Interconnects for Smart Garments: Design, Fabrication, and Characterization
Direct-Write Spray Coating of a Full-Duplex Antenna for E-Textile Applications
Recent advancements in printing technologies have greatly improved the fabrication efficiency of flexible and wearable electronics. Electronic textiles (E-textiles) garner particular interest because of their innate and desirable properties (i.e., conformability, breathability, fabric hand), which make them the ideal platform for creating wireless body area networks (WBANs) for wearable healthcare applications. However, current WBANs are limited in use due to a lack of flexible antennas that can provide effective wireless communication and data transfer. In this work, we detail a novel fabrication process for flexible textile-based multifunctional antennas with enhanced dielectric properties. Our fabrication process relies on direct-write printing of a dielectric ink consisting of ultraviolet (UV)-curable acrylates and urethane as well as 4 wt.% 200 nm barium titanate (BT) nanoparticles to enhance the dielectric properties of the naturally porous textile architecture. By controlling the spray-coating process parameters of BT dielectric ink on knit fabrics, the dielectric constant is enhanced from 1.43 to 1.61, while preserving the flexibility and air permeability of the fabric. The novel combination textile substrate shows great flexibility, as only 2 N is required for a 30 mm deformation. The final textile antenna is multifunctional in the sense that it is capable of operating in a full-duplex mode while presenting a relatively high gain of 9.12 dB at 2.3 GHz and a bandwidth of 79 MHz (2.260–2.339 GHz) for each port. Our proposed manufacturing process shows the potential to simplify the assembly of traditionally complex E-textile systems
Formation of novel photoluminescent hybrid materials by sequential vapor infiltration into polyethylene terephthalate fibers
Photoluminescence Mechanism and Photocatalytic Activity of Organic–Inorganic Hybrid Materials Formed by Sequential Vapor Infiltration
Photoremediation of heavy metals from aqueous environments onto ZnO coated fibrous polyethylene terephthalate nonwovens
Conformal Atomic Layer Deposition of Alumina on Millimeter Tall, Vertically-Aligned Carbon Nanotube Arrays
Atomic
layer deposition (ALD) can be used to coat high aspect ratio and high
surface area substrates with conformal and precisely controlled thin
films. Vertically aligned arrays of multiwalled carbon nanotubes (MWCNTs)
with lengths up to 1.5 mm were conformally coated with alumina from
base to tip. The nucleation and growth behaviors of Al<sub>2</sub>O<sub>3</sub> ALD precursors on the MWCNTs were studied as a function
of CNT surface chemistry. CNT surfaces were modified through a series
of post-treatments including pyrolytic carbon deposition, high temperature
thermal annealing, and oxygen plasma functionalization. Conformal
coatings were achieved where post-treatments resulted in increased
defect density as well as the extent of functionalization, as characterized
by X-ray photoelectron spectroscopy and Raman spectroscopy. Using
thermogravimetric analysis, it was determined that MWCNTs treated
with pyrolytic carbon and plasma functionalization prior to ALD coating
were more stable to thermal oxidation than pristine ALD coated samples.
Functionalized and ALD coated arrays had a compressive modulus more
than two times higher than a pristine array coated for the same number
of cycles. Cross-sectional energy dispersive X-ray spectroscopy confirmed
that Al<sub>2</sub>O<sub>3</sub> could be uniformly deposited through
the entire thickness of the vertically aligned MWCNT array by manipulating
sample orientation and mounting techniques. Following the ALD coating,
the MWCNT arrays demonstrated hydrophilic wetting behavior and also
exhibited foam-like recovery following compressive strain