Performance Enhancement of a Quartz Tuning Fork Sensor Using a Cellulose Nanocrystal-Reinforced Nanoporous Polymer Fiber.

A cellulose nanocrystal (CNC)-reinforced polymethylmethacrylate (PMMA) fiber was obtained via electrospinning, and then attached between the two tines of a quartz tuning fork (QTF). The change in the resonance frequency of the CNC/PMMA composite fiber-coated QTF (CP-QTF) was measured upon being exposed to various concentrations of ethanol vapor. The frequency decreased as the ethanol vapor concentration increased, because the modulus of the composite fiber decreased due to the adsorption of the ethanol vapor.

Growth of hierarchical gold clusters for use in superomniphobic electrodes.

We developed a method to fabricate a superomniphobic gold electrode by synthesizing hierarchical gold clusters on a gold substrate and treating the surface with low surface energy materials. The reduction of gold ions was repeated several times, causing the gold microparticles to grow in random directions and form hierarchical gold clusters. Treatment of the gold structures with perfluorothiol resulted in a superhydrophobic surface that also exhibited superoleophobicity for oils and liquids with surface tensions as low as 25.

Effect of liquid droplet surface tension on impact dynamics over hierarchical nanostructure surfaces.

Analyzing impact dynamics is important for practical applications of superhydrophobic surfaces, because these nonwetting surfaces frequently encounter impacting liquid droplets in real environments. Thus, various studies have been conducted to investigate impact dynamics by examining the correlation between the behaviors of impacting liquid droplets and several determining parameters, such as impacting velocity, surface structure and surface energy. The impacting behaviors of pure water droplets were the main focus in most previous studies; the effect of surface tension, another critical parameter, on impact dynamics has rarely been investigated.

Performance Enhancement of a Microfabricated Resonator Using Electrospun Nanoporous Polymer Wire.

A nanoporous poly(methyl methacrylate) (PMMA) wire was prepared by electrospinning under high humidity and attached between two prongs of a microfabricated quartz tuning fork (QTF). Exposure of the QTF to ethanol vapor caused a frequency shift due to a decrease in the modulus of the PMMA wire, and the frequency change increased as the concentration of ethanol vapor increased. The nanoporous wire-coated QTF exhibited higher sensitivity and faster response time than a plain wire-coated QTF, which was attributed to the high surface area and pore networks facilitating the transport of ethanol molecules inside the PMMA wire.

Dual dimensional nanostructures with highly durable non-wetting properties under dynamic and underwater conditions.

Non-wetting states with high durability under both dynamic and underwater conditions are very desirable for practical applications of superhydrophobic surfaces in various fields. Despite increasing demands for this dual stability of non-wetting surfaces, studies investigating both the impact dynamics and underwater stability are very rare. In the current study, we performed water droplet impact dynamics and underwater stability studies using ZnO/Si hierarchical nanostructures (HNs) as a model system.

Magnetorheological Elastomer Films with Tunable Wetting and Adhesion Properties.

We fabricated magnetorheological elastomer (MRE) films consisting of polydimethylsiloxane and various concentrations of fluorinated carbonyl iron particles. The application of a magnetic field to the MRE film induced changes in the surface morphology due to the alignment of the iron particles along the magnetic field lines. At low concentrations of iron particles and low magnetic field intensities, needle-like microstructures predominated.

Adsorption and desorption characteristics of alcohol vapors on a nanoporous ZIF-8 film investigated using silicon microcantilevers.

Zinc oxide nanorods were synthesized directly on a silicon microcantilever and converted into a nanoporous ZIF-8 film via a solvothermal reaction. The simultaneous measurements of the resonance frequency and deflection of the cantilever revealed that the adsorption of alcohol vapors induced a structural change in the ZIF-8 framework.