Platinum substrate for surface plasmon microscopy at small angles

Sensitive Aluminum SPR Sensors Prepared by Thermal Evaporation Deposition

We used straightforward thermal evaporation deposition to form thin Al films on fused silica slides as surface plasmon resonance (SPR) sensors in the blue visible region. Compared to other studies, we achieved high-quality Al SPR sensors with a low vacuum level at 7 × 10-4 Pa and a low deposition rate between 1.47 and 3.41 nm/s. These Al films have an atomic-level surface roughness. With our recipe, the requirements for deposition conditions are relaxed, and the operation time is reduced remarkably. The experimental sensitivity of the bulk refractive index measurements using 405 nm probing light is as high as 149.9°/RIU. Compared with other studies, our blue visible Al SPR completes the Al SPR working frequency range from deep UV to near-infrared which is much broader than the working range of Au SPR sensors. The cost of Al material is cheap, and the deposition instrument is also economic and operation easy. Considering the compatibility with most of the nanofabrication procedures and stability from the native oxide layer, Al SPR sensors have a huge potential to replace Au SPR sensors as the new golden standard of SPR sensing technology.

Pt nanoparticles utilized as efficient ultraviolet plasmons for enhancing whispering gallery mode lasing of a ZnO microwire via Ga-incorporation

Introducing nanostructured metals with ultraviolet plasmonic characters has attracted much attention for fabricating high performance optoelectronic devices in the shorter wavelength spectrum. In this work, platinum nanoparticles (PtNPs) with controlled plasmonic responses in ultraviolet wavelengths were successfully synthesized. To demonstrate the promising availability, PtNPs with desired sizes were deposited on a hexagonal ZnO microwire via Ga-doping (PtNPs@ZnO:Ga MW). Under ultraviolet illumination, typical near-band-edge emission of ZnO:Ga MW was considerably enhanced; meanwhile, the photocurrent is much larger than that of the bare MW. Thereby, the enhanced phenomena of a ZnO:Ga MW is related to localized surface plasmon resonances of the decorated PtNPs. A single MW with a hexagonal cross-section can be a potential platform to construct a whispering gallery mode (WGM) cavity due to its total inner wall reflection. Given this, the influence of PtNPs via ultraviolet plasmons on lasing features of the ZnO:Ga MW was tested. The lasing characteristics are significantly enhanced, including lasing output enhancement, a clear reduction of the threshold and the improvement of the quality factor. To exploit the working principle, PtNPs serving as powerful ultraviolet plasmons can couple with ZnO:Ga excitons, accelerating radiative recombination. Since fabricating stable, typical nanostructured metals with ultraviolet plasmons remains a challenging issue, the results illustrated in the work may offer a low-cost and efficient scheme for achieving plasmon-enhanced wide-bandgap semiconductor based ultraviolet optoelectronic devices with excellent performances.

Surface Functionalization of Platinum Electrodes with APTES for Bioelectronic Applications

The interface between electronic components and biological objects plays a crucial role in the success of bioelectronic devices. Since the electronics typically include different elements such as an insulating substrate in combination with conducting electrodes, an important issue of bioelectronics involves tailoring and optimizing the interface for any envisioned applications. In this paper, we present a method for functionalizing insulating substrates (SiO₂) and metallic electrodes (Pt) simultaneously with a stable monolayer of organic molecules ((3-aminopropyl)triethoxysilane (APTES)). This monolayer is characterized by high molecule density, long-term stability, and positive surface net charge and most likely represents a self-assembled monolayer (SAM). It facilitates the conversion of biounfriendly Pt surfaces into biocompatible surfaces, which allows cell growth (neurons) on both functionalized components, SiO₂ and Pt, which is comparable to that of reference samples coated with poly-L-lysine (PLL). Moreover, the functionalization greatly improves the electronic cell-chip coupling, thereby enabling the recording of action potential signals of several millivolts at APTES-functionalized Pt electrodes.