Ústav mikroelektroniky

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Tantalum electrodeposition using a nanoporous anodic alumina template and a nanostructured gold/nickel-chromium glass-ceramic substrate
(PERGAMON-ELSEVIER SCIENCE LTD, 2025-05-21) Šimůnková, Helena; Kolíbalová, Eva; Kalina, Lukáš; Lednický, Tomáš; Bábor, Petr; Hubálek, Jaromír
The electrodeposition and analysis of tantalum (Ta) nanotube arrays prepared from an ionic liquid, 1-butyl-1methylpyrrolidinium bis(trifluoro-methylsulfonyl) imide (BMP[Tf2N]), using a porous anodic alumina (PAA) template are newly presented. Free-standing and spatially separated tantalum nanotube arrays were achieved after selective etching of the PAA. The high-rate electrodeposition of the nanotube arrays took only 10 s and achieved approximately 70 atomic percent Ta metal. Superficial X-ray photoelectron spectroscopy supplemented by an argon ion etching and depth profiling has proven the presence of tantalum metal. Additionally, tantalum electrodeposition was attempted using a sputter-deposited gold coating on a planar glass-ceramic substrate as the working electrode. Pores emerged within the sputter-deposited gold layer as a side result of the Ta electrodeposition step. Nano-to submicrometer large pores were created due to a foreign element penetration into the gold and etching effect of fluorides contained in the ionic liquid solution.
Adaptability of Electrospun PVDF Nanofibers in Bone Tissue Engineering
(MDPI, 2025-01-25) Havlíková, Tereza; Papež, Nikola; Fohlerová, Zdenka; Kaspar, Pavel; Dallaev, Rashid; Částková, Klára; Ţălu, Ştefan
This study focused on the development of a suitable synthetic polymer scaffold for bone tissue engineering applications within the biomedical field. The investigation centered on electrospun polyvinylidene fluoride (PVDF) nanofibers, examining their intrinsic properties and biocompatibility with the human osteosarcoma cell line Saos-2. The influence of oxygen, argon, or combined plasma treatment on the scaffold’s characteristics was explored. A comprehensive design strategy is outlined for the fabrication of a suitable PVDF scaffold, encompassing the optimization of electrospinning parameters with rotating collector and plasma etching conditions to facilitate a subsequent osteoblast cell culture. The proposed methodology involves the fabrication of the PVDF tissue scaffold, followed by a rigorous series of fundamental analyses encompassing the structural integrity, chemical composition, wettability, crystalline phase content, and cell adhesion properties.
Arrays of ultra-thin selenium-doped zirconium-anodic-oxide nanorods as potential antibacterial coatings
(ROYAL SOC CHEMISTRY, 2025-01-17) Kamnev, Kirill; Bendová, Mária; Fohlerová, Zdenka; Fialová, Tatiana; Martyniuk, Oleh; Prášek, Jan; Číhalová, Kristýna; Mozalev, Alexander
Two characteristic types of extraordinarily thin upright-standing ZrO2-based nanorods self-aligned on a substrate, differing in diameters (20/30 nm), lengths (90/120 nm), and population densities (1.1/4.6 × 1010 cm2), were synthesized via the porous-anodic-alumina (PAA)-assisted anodization of Zr in 1.5 M selenic acid followed by selective PAA dissolution. A needle-like shape was achieved due to the unique formation of zirconium anodic oxide in extremely thin nanopores that grow only in selenic acid. The SEM, XPS, and Raman spectroscopy analyses revealed that the nanorods feature a core/shell structure in which the core is stoichiometric amorphous ZrO2, and the shell is 6 nm thick hydroxylated zirconium dioxide ZrO2x(OH)2x mixed with Al2O3. The core and shell incorporated electrolyte-derived selenate (SeO42) ions, which replace up to 1% of the O2 ions in the nanorod surface layer. Besides, nanoparticles of elemental Se were deposited on the top of rods during anodic polarization. A model was developed for the cooperative ionic transport and electrochemical and solid-state reactions during the PAA-assisted growth of zirconium oxide in selenic acid. The two Se-doped top-decorated zirconium-oxide nanorod arrays were examined as potential antibacterial nanomaterials toward G-negative E. coli and G-positive S. aureus, using direct SEM observations of the bacteria–surface interfaces and carrying out the modified Japanese Industrial Standard test for antimicrobial activity and efficacy, JIS Z 2801. While specific differences in interaction with each type of bacteria were observed, both nanostructures caused a significant harmful synergetic effect on the bacteria, acting as non-metallic (Se) ion-releasing bactericidal coatings along with repellent and contact-killing activities arising from extraordinary needle-like nanoscale surface engineering.
Design of Shadow Filter Using Low-Voltage Multiple-Input Operational Transconductance Amplifiers
(MDPI, 2025-01-14) Kumngern, Montree; Khateb, Fabian; Kulej, Tomasz; Wattikornsirikul, Natchayathorn
This paper introduces shadow filters that employ multiple-input operational transconductance amplifiers (MI-OTAs) as the active component. Two configurations of shadow filters are proposed. The first configuration, in contrast to previous designs, enables the adjustment of the quality factor without affecting the passband gains of the BPF, LPF, and HPF, thus achieving optimal frequency responses for these filters. The second configuration allows for the variation of the natural frequency without impacting the passband gains of the HPF, LPF, and BPF, maintaining constant passband gains. Moreover, the natural frequency can be electronically controlled by modifying parameters of the original biquad filters, providing advantages in compensating for process, voltage, and temperature variations. The MI-OTA is designed to provide multiple-input differential terminals using the multiple-input bulk-driven MOS transistor (MIBD-MOST) technique, allowing differential input signals to be converted into current output through its transconductance gain. The OTA operates at a supply voltage of 450 mV and consumes 81 nW of power, with the MOS transistors operating in weak inversion. The OTA and shadow filters were designed and simulated using a 0.18 mu m CMOS process to validate the functionality and performance of the proposed circuits.
MoOx-based high-density nanoarrays on a substrate via smart anodizing as novel 3D electrodes for nano-energy applications
(Royal Society of Chemistry, 2025-05-27) Mozalev, Alexander; Bendová, Mária; Kalina, Lukáš; Prášek, Jan; Gispert-Guirado, Francesc; Llobet, Eduard
For the first time, arrays of MoOx-based nanostructures of various sizes and morphologies, vertically aligned on a substrate, have been synthesized self-organized via the PAA-assisted anodization of a Mo layer through a very thin Nb interlayer. Such a smart anodization enabled the nucleation and sustainable growth of fully amorphous MoOx nanostructures within and under the PAA nanopores, which is impossible by direct molybdenum anodizing or other methods. The MoOx-based nanoarrays revealed the potential for applications in semiconductor nanoelectronics where the intensive and localized at the nanoscale electron transport, reversible redox reactions, high population density of nanochannels, and tailored crystallinity are in demand. The disclosed intercalation pseudocapacitance behavior of the rods' cores and the competitive performance metrics make the films promising as nanostructured electrodes for on-chip energy-related applications. The works to improve the electron-transport properties of the shells, explore field-emission and memristive potentials of the nanoarrays, and design relevant device configurations are in progress and will be reported in due course.

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