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FUNCTIONAL TUNGSTEN-BASED THIN FILMS AND THEIR CHARACTERIZATION
(TANGER Ltd, 2024-01-08) Košelová, Zuzana; Horáková, Lenka; Sobola, Dinara; Burda, Daniel; Knápek, Alexandr; Fohlerová, Zdenka
Anodization is a technique that can be used to create thin layers of oxide on the surface. Thin oxide layers have been found to be useful in a variety of applications, including emitters of electrons. Tungsten is still often choice for cold field emitters in commercial microscopy applications. His suitable quality can be improved even more by deposition of thin layer. Not only emission characteristic can be improved, but also emitter operating time can be prolonged. Tungsten oxide is known for its excellent resistance to corrosion and chemical attack, which is due to its stable crystal structure and the strong chemical bonds between tungsten and oxygen atoms. Many techniques were applied for this purpose, with various advantages and disadvantages. For this work anodization was chosen because of controllable uniform material coverage and easy accessibility without the need for expensive complex equipment. The anodization process involves applying an electrical potential to tungsten while it is immersed in an electrolyte solution. This causes a thin layer of tungsten oxide to form on the surface of the metal. The thickness and properties of the resulting oxide layer can be controlled by adjusting the anodization conditions, such as the electrolyte solution, voltage, and the duration of the process. In this work, H3PO4 was used as electrolyte To test whether these tungsten oxide layers would be viable for electron emitters, for use in electron guns and other devices that require high-quality electron emitters, we put them through a series of tests. Properties were evaluated using appropriate techniques. In general, anodization of tungsten to create thin tungsten oxide layers is a promising technique for producing high-quality electron emitters.
Vertical organic electrochemical transistor platforms for efficient electropolymerization of thiophene based oligomers
(ROYAL SOC CHEMISTRY, 2024-04-18) Gryszel, Maciej; Byun, Donghak; Burtscher, Bernhard; Abrahamsson, Tobias; Brodský, Jan; Simon, Daniel Theodore; Berggren, Magnus; Glowacki, Eric Daniel; Strakosas, Xenofon; Donahue, Mary
Organic electrochemical transistors (OECTs) have emerged as promising candidates for various fields, including bioelectronics, neuromorphic computing, biosensors, and wearable electronics. OECTs operate in aqueous solutions, exhibit high amplification properties, and offer ion-to-electron signal transduction. The OECT channel consists of a conducting polymer, with PEDOT:PSS receiving the most attention to date. While PEDOT:PSS is highly conductive, and benefits from optimized protocols using secondary dopants and detergents, new p-type and n-type polymers are emerging with desirable material properties. Among these, low-oxidation potential oligomers are highly enabling for bioelectronics applications, however the polymers resulting from their polymerization lag far behind in conductivity compared with the established PEDOT:PSS. In this work we show that by careful design of the OECT geometrical characteristics, we can overcome this limitation and achieve devices that are on-par with transistors employing PEDOT:PSS. We demonstrate that the vertical architecture allows for facile electropolymerization of a family of trimers that are polymerized in very low oxidation potentials, without the need for harsh chemicals or secondary dopants. Vertical and planar OECTs are compared using various characterization methods. We show that vOECTs are superior platforms in general and propose that the vertical architecture can be expanded for the realization of OECTs for various applications. Vertical organic electrochemical transistor platforms enable facile channel formation by electropolymerization. The improved deposition control and resulting high performance is demonstrated here with the trimer ETE-COONa.
Shedding Light on Cardiac Excitation: In Vitro and In Silico Analysis of Native Ca²⁺ Channel Activation in Guinea Pig Cardiomyocytes Using Organic Photovoltaic Devices
(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2024-06-03) Rienmüller, Theresa; Shrestha, Niroj; Polz, Mathias; Stoppacher, Sara; Ziesel, Daniel; Migliaccio, Ludovico; Pelzmann, Brigitte; Lang, Petra; Zorn-Pauly, Klaus; Langthaler, Sonja; Opančar, Aleksandar; Baumgartner, Christian; Üçal, Muammer; Schindl, Rainer; Derek, Vedran; Scheruebel, Susanne
Objective: This study aims to explore the potential of organic electrolytic photocapacitors (OEPCs), an innovative photovoltaic device, in mediating the activation of native voltage-gated Cav1.2 channels (I-Ca,I-L) in Guinea pig ventricular cardiomyocytes. Methods: Whole-cell patch-clamp recordings were employed to examine light-triggered OEPC mediated I-Ca,I-L activation, integrating the channel's kinetic properties into a multicompartment cell model to take intracellular ion concentrations into account. A multidomain model was additionally incorporated to evaluate effects of OEPC-mediated stimulation. The final model combines external stimulation, multicompartmental cell simulation, and a patch-clamp amplifier equivalent circuit to assess the impact on achievable intracellular voltage changes. Results: Light pulses activated I-Ca,I-L, with amplitudes similar to voltage-clamp activation and high sensitivity to the L-type Ca2+ channel blocker, nifedipine. Light-triggered I-Ca,I-L inactivation exhibited kinetic parameters comparable to voltage-induced inactivation. Conclusion: OEPC-mediated activation of I-Ca,I-L demonstrates their potential for nongenetic optical modulation of cellular physiology potentially paving the way for the development of innovative therapies in cardiovascular health. The integrated model proves the light-mediated activation of I-Ca,I-L and advances the understanding of the interplay between the patch-clamp amplifier and external stimulation devices. Significance: Treating cardiac conduction disorders by minimal-invasive means without genetic modifications could advance therapeutic approaches increasing patients' quality of life compared with conventional methods employing electronic devices.
Structural and electrical characterization of cadmium phosphate glasses doped with different concentration of sodium chloride
(IOP Publishing, 2024-12-01) Assayed, Ghada A.I.; Shaheen, Adel A; Alsoud, Ammar Awadallah Ahmad; Al-Bashaish, Saleh R.; Mousa, Marwan Suleiman; Knápek, Alexandr; Sobola, Dinara
The electrical characteristics of cadmium phosphate glasses doped with varying concentrations of sodium chloride [ Cd-3( PO4)(2)](1-x) [ NaCl](x) , where x = 0, 2, 4 ,6 mol.% NaCl, were investigated with respect to both dopant levels and temperature. Electrical impedance spectroscopy was employed, and impedance measurements were taken across the frequency spectrum from 10(2) Hz to 10(6) Hz. Samples were characterized by scanning electron microscopy-energy dispersive x-ray spectroscopy, x-ray diffraction analysis and Fourier Transform Infrared Spectroscopy. The fi ndings revealed a decrease in bulk resistance with increasing temperature and dopant concentration, indicating a rise in DC- conductivity and suggesting a semiconducting behavior in the material. Moreover, the activation energy values were noted to decrease as dopant concentration increased. Analysis of the AC-conductivity variation with frequency delineated two distinct regions: a low-frequency region where AC-conductivity increased with frequency, indicative of a "pumping force" effect aiding charge carrier movement through various conduction states, and a high-frequency region or frequency-independent zone signifying a transition towards a more ohmic behavior in the material. The study highlighted a decrease in both the dielectric constant and dielectric loss with rising temperature and frequency across all dopant concentrations. Furthermore, the Reaction Coefficient "s" was found to be less than one, suggesting that the conduction mechanism can be elucidated in terms of the Correlated Barrier Hopping ( CBH ) model.
A 0.3 V Current Differencing Buffered Amplifier and Its Application in Current-Mode Third-Order Low-Pass Filters
(MDPI, 2025-05-25) Khateb, Fabian; Kumngern, Montree; Kulej, Tomasz
This paper introduces an innovative low-voltage, low-power current differencing buffered amplifier (CDBA). The proposed CDBA utilizes a bulk-driven MOS transistor operating in the subthreshold region, allowing it to function effectively at low supply voltages while minimizing power consumption, making it suitable for sensor and biomedical applications. To demonstrate the performance of the proposed CDBA, it is incorporated into the design of a current-mode, third-order low-pass filter that is specifically tailored for bio-sensing applications. Both the CDBA and the low-pass filter are designed and simulated in Cadence Virtuoso using the TSMC 0.18 mu m CMOS process. The CDBA operates at a supply voltage of 0.3 V, consuming 170 nW of power, while the third-order low-pass filter achieves a dynamic range of 57.2 dB with a total harmonic distortion (THD) of 1%.

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