Preparation of Micro Gold Devices on Poly(dimethylsiloxane) Chips with Region-Selective Electroless Plating

Metal Microcapsules Prepared via Electroless Plating at Liquid-Liquid Interface

We report the facile preparation of metal microcapsules via the formation of a Pickering emulsion, stabilized by catalytic palladium nanoparticles (PdNPs), and subsequent electroless plating at an oil-water interface induced by the adsorbed PdNPs. Metal microcapsules with smooth metal shells are formed by simply agitating the mixture of the plating solution and 1,2-dichloroethane containing poly(vinylpyrrolidone)-coated PdNPs, without external heating or electrical sources as energy inputs. We found that the metal microcapsules had thin copper metal shells with a relatively smooth surface and metallic luster. The metal shells were composed of more than 99 atom % copper in the form of Cu and Cu₂O. We believe that this simple metal microcapsule preparation method may be beneficial to produce novel functional microcapsules with metal shells.

Free-Standing Metal Films Prepared via Electroless Plating at Liquid-Liquid Interfaces

We report a simple preparation of free-standing metal films via electroless plating (ELP) at the liquid-liquid (L-L) interface between an aqueous electroless plating solution and an organic solvent. The use of ELP does not require any external energy in the form of heating and stirring. We find that the affinity of the organic solvent for the palladium nanoparticles (PdNPs) as catalysts and the vertical position of the organic and aqueous phases in the biphasic system are important considerations for synthesizing a robust copper film. Specifically, 1,2-dichloroethane which has an appropriate affinity for PdNPs and a higher density than water was found to be a good candidate for use as the organic phase in this system. However, a poor-quality copper film was obtained in the system with 1-hexanol as the organic phase. We also controlled the microscale surface structure of the copper films by using different concentrations of the injected PdNP dispersion. A high density of PdNPs caused smaller regions of metal growth, which contributed to the formation of smoother metal films. Moreover, under the optimal synthesis condition, we confirmed the electrical conductivity of the obtained copper film to be 1.16 × 10^-7 Ωm. We believe that this metal film preparation represents a promising way to produce a range of metal film structures through the use of flexible L-L interfaces as templates.

Polymer Interface Molecular Engineering for E-Textiles

Wearable electronics, regarded as the next generation of conventional textiles, have been an important concept in the study of e-textiles. Conductive fibres are the upstreaming of e-textiles and have witnessed the booming development in recent years. However, little work has focused on improving the wash ability and durability of conductive fibres. As a new approach to manufacturing conductive fibres, Polymer Interface Molecular Engineering (PIME) is starting to be employed recently, to build up an interfacial layer on polymeric fibre surfaces; this interfacial layer services as a platform to anchor catalysts for the following metal Electroless Deposition (ELD). The designed interfacial layer significantly increases adhesion between polymeric substrates and coating metal layers, to improve the durability of e-textiles. This review highlights recent research into different molecular and architectural design strategies, and its potential application for wearable electronics. Further challenges and opportunities in this field are also discussed critically.

CNT-TiO2 coating bonded onto stainless steel wire as a novel solid-phase microextraction fiber

A novel solid-phase microextraction (SPME) fiber based on carbon nanotubes-titanium oxide (CNT-TiO2) composite coating bonded onto stainless steel wire was prepared via electroless plating and sol-gel techniques. The SPME coating was characterized by scanning electron microscopy and Raman microscopy. Coupled to gas chromatography (GC), the fiber was investigated with seven polycyclic aromatic hydrocarbons (PAHs) in direct-immersion mode. The SPME-GC analytical method was evaluated under optimized extraction conditions. Compared with other reports, higher sensitivity (LODs, 0.002-0.004 μg L(-1)) and better linear range (0.01-100 and 0.01-200 μg L(-1)) were obtained by the proposed method. The fiber exhibited high thermal stability to 300 °C and excellent durability in HCl and NaOH solutions. The as-established SPME-GC method was used to analyze the real water samples and satisfactory results were obtained.

Reductive surface synthesis of gold nanoparticles on silicate glass and their biochemical sensor applications

Gold nanoparticles (Au NPs) were directly synthesized on the surface of polyvinylsilazane (PVSZ, -[(vinyl)SiH-NH2]-) without use of extra reductive additives. The reductive Si-H functional groups on the surface of cured PVSZ acted as surface bound reducing agents to form gold metal when contacted with an aqueous Au precursor (HAuCl4) solution, leading to formation of Au NPs adhered to silicate glass surface. The Au NPs-silicate platforms were preliminarily tested to detect Rhodamine B (1 μM) by surface enhanced Raman scattering. Furthermore, gold microelectrode obtained by post-chemical plating was used as an integrated amperometric detection element in the polydimethylsilane-glass hybrid microfluidic chip.