Micro and Nanosystems - Volume 16, Issue 3, 2024

Zetasizer is an advanced device that measures various properties of particles or molecules suspended in a liquid medium. It is extensively used for evaluating the size of nanoparticles, colloids, and biomolecular particles, and for determining particle charge. There are several analytical techniques by which the size, zeta potential, and molecular weight can be determined, like Dynamic Light Scattering (DLS) that measures the size of particles in dispersed systems, which can range from sub-nanometers to several micrometers in diameter. Electrophoretic Light Scattering (ELS) analyzes the mobility and charge of particles, also known as the zeta potential. Static Light Scattering (SLS) determines the molecular weight of particles in a solution. The Zetasizer is part of the Zetasizer Advance range of benchtop systems available for laboratory use. The Zetasizer Ultra model offers unique measurement capabilities, such as Multi-angle Dynamic Light Scattering (MADLS) and particle concentration. These features offer a deeper understanding of samples, making the Zetasizer a vital instrument in numerous scientific and industrial applications. In this review, we have discussed Zetasizer's principles for the determination of particle size, zeta potential, and molecular weight, along with its qualification and applications in different formulations.

Microneedles represent a revolutionary advancement in drug delivery and diagnostics, offering a minimally invasive approach to accessing the intricate biological environment of the human body. These micron-sized needles, typically ranging from 25 to 1000 micrometers in length, penetrate the outermost layer of the skin, creating microchannels that facilitate the transdermal administration of therapeutics or the extraction of interstitial fluid for analysis. This innovative technology holds great promise for enhancing patient compliance, reducing side effects, and improving the overall efficiency of drug delivery. Integrating microneedles with wearable devices further amplifies their potential impact. Wearable devices provide a seamless interface for monitoring and controlling microneedle-based systems, fostering real-time data collection and personalized healthcare. Such devices can be designed to administer precise drug doses at predetermined intervals, adapting treatment regimens to individual patient needs. Additionally, the combination of microneedles and wearable devices enables continuous monitoring of biomarkers through the extraction of interstitial fluid, offering a non-invasive method for disease diagnosis and management. The review also provides a detailed overview of the mechanisms, types, fabrication techniques, applications, and patents for integrating microneedles with wearable devices. This symbiotic relationship between microneedles and wearables opens new paths for patient-centric healthcare, with the potential to transform chronic disease management and streamline therapeutic interventions. As these technologies continue to evolve, their integration may pave the way for personalized, on-demand healthcare solutions, accompanying a new era of patient well-being and treatment efficacy.

Introduction: Photonic devices play a pivotal role in the realm of high-speed data communication due to their inherent capability to expedite the transfer of information. Historically, research efforts in this domain have predominantly concentrated on investigating the fundamental mode propagation within photonic waveguides. Methods: This study diverges from the conventional approach by delving into the untapped potential of higher-order modes in addition to the fundamental mode of propagation. The exploration of these higher-order modes opens up new possibilities for optimizing and enhancing the performance of photonic devices in high-speed data communication scenarios. As a distinctive aspect of this study, various coating materials were scrutinized for their impact on both fundamental and higher-order mode propagation. The materials under examination included AlN (aluminum nitride), Germanium, and Silicon. These materials were chosen based on their unique optical properties and suitability for influencing different modes of light propagation. The findings from the study reveal that applying a coating of germanium demonstrates advantageous characteristics, particularly in terms of reduced signal loss, even when considering higher-order modes of propagation within photonic devices. Results: In this context, the results indicate that germanium-coated waveguides exhibit notably low propagation losses, with measurements as minimal as 0.25 dB/cm. This low level of loss is particularly noteworthy, especially when the waveguide has a width of 550 nm and is coated with a thickness of 50 nm. The dimensions and coating specifications play a crucial role in determining the efficiency of light transmission within the waveguide. Conclusion: The fact that the propagation loss is substantially low under these conditions suggests that the germanium-coated waveguide, even when considering higher-order modes of light propagation, can effectively maintain the integrity of the optical signal.

Aims: The aim of this paper is to develop a new, simple equation for deep spherical indentations. Background: The Hertzian theory is the most widely applied mathematical tool when testing soft materials because it provides an elementary equation that can be used to fit force-indentation data and determine the mechanical properties of the sample (i.e., its Young's modulus). However, the Hertz equation is only valid for parabolic or spherical indenters at low indentation depths. For large indentation depths, Sneddon's extension of the Hertzian theory offers accurate force-indentation equations, while alternative approaches have also been developed. Despite ongoing mathematical efforts to derive new accurate equations for deep spherical indentations, the Hertz equation is still commonly used in most cases due to its simplicity in data processing. Objective: The main objective of this paper is to simplify the data processing for deep spherical indentations, primarily by providing an accurate equation that can be easily fitted to force-indentation data, similar to the Hertzian equation. Methods: A simple power-law equation is derived by considering the equal work done by the indenter using the actual equation. Results: The mentioned power-law equation was tested on simulated force-indentation data created using both spherical and sphero-conical indenters. Furthermore, it was applied to experimental force-indentation data obtained from agarose gels, demonstrating remarkable accuracy. Conclusion: A new elementary power-law equation for accurately determining Young's modulus in deep spherical indentation has been derived.

Background: Nickel-titanium (NiTi) orthodontic wires are widely used in dental corrective procedures due to their high mechanical properties and cost-effectiveness. However, they are prone to oral corrosion, leading to mechanical deterioration, aesthetic issues, and potential health concerns. Objective: This study aims to improve the corrosion resistance and durability of NiTi orthodontic wires by employing zirconium dioxide (ZrO2) and Nafion coating with the goal of enhancing wire performance. Methods: Two types of NiTi wires were evaluated: a standard, unmodified wire as a control and another wire treated with electrodeposited ZrO2 film and Nafion (Naf) coating. Surface analysis was conducted using various techniques, including Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Spectroscopy (EDX) analysis. Results: The uncoated NiTi wire exhibited a corrosion rate of 4.436× 10^-1 mm/year, whereas the NAF/ZrO2-coated NiTi wire showed a corrosion rate of 4.068× 10^-1 mm/year, indicating that the NAF/ZrO2 coating acted as a protective layer. Additionally, the ZrO2 layer provided poor electrical conductivity, resulting in slightly higher impedance compared to bare NiTi. The coating served as a barrier, which significantly enhanced corrosion resistance and improved the wire lifespan. Conclusion: Electro-modification through ZrO2 deposition and Nafion coating significantly improved the corrosion resistance and overall durability of NiTi orthodontic wires, offering a promising advancement for their use in dental orthodontics. This study underscores the potential of ZrO2 and Nafion coating to enhance the corrosion resistance and longevity of NiTi orthodontic wires.