Miniaturization Of Technology Research Articles

Ultraviolet-visible spectroscopy with all-dielectric multi-foci dispersive metalens

Metasurfaces are a cutting-edge development in optical technology miniaturization, enabling the manipulation of light at a microscopic scale while providing unprecedented control over its intrinsic characteristics, such as amplitude, polarization, and phase. Researchers have been making significant progress in advancing and developing high-efficiency and functionally versatile metasurfaces, aiming to achieve miniaturization and overcoming the technological limitations of conventional components. This article is intended to develop a single-layered, highly transmissive all-dielectric multi-foci metalens that serves as a compact spectrometer for portable investigative measurements within the ultraviolet to the visible spectrum, especially for 290–460nm band. The proposed metalens can achieve top-notch performance by precisely mapping the wavelength information into subwavelength diffraction-limited focusing spots. This approach helps in accomplishing simultaneous spectral splitting and focusing on the same plane. The proposed metalens consists of an array of intelligently optimized nanoantennas made of a CMOS-compatible silicon nitride material. It exploits a unique phase and wavelength multiplexing strategy to create highly dispersive multi-foci metalens, making it an ideal choice for an ultra-compact, high-resolution, and dual-band meta-spectrometer. We expect our proposed framework to have numerous applications in the industrial and medical fields, enabling diagnosis, detection, and assessment within a compact platform.

Phase demodulation method of high line density grating interferometric signal based on wavelet transform

The increasing line density of the reference grating and the accelerating miniaturization of ultra-precision displacement measurement technology necessitate more stable interferometric signal processing methods for high line density gratings, particularly in low signal-to-noise ratio scenarios. This paper presents a phase demodulation method for dynamic interferometric signals for high line density gratings. The Morlet wavelet transform is utilized to obtain the instantaneous frequency of the interferometric signal, integration of which yields the relative displacement, while adding adjacent relative displacements without gaps provides the absolute displacement during dynamic motion of the grating. In simulations with a signal-to-noise ratio ranging from 40 to 70 dB, the proposed method demonstrates greater robustness compared to the traditional method. By establishing a platform for repeated experiments and comparing it with traditional methods, it was found that the maximum deviation between calculation results obtained using this method and traditional methods is 0.8 nm, further confirming its potential application.

Encoding independent wavefronts in a single metasurface for high-order optical vortex recognition

The orbital angular momentum (OAM) of vortex beams has great potential in optical communications due to its communication confidentiality and low crosstalk. It is necessary to design a plausible OAM pattern recognition mechanism. Abandoning AI models that require large datasets, a single passive all-dielectric metasurface consisting of TiO2 nanopillars on a SiO2 substrate is used to recognize high-order optical vortexes. In this configuration, the proposed device is capable of simultaneously encoding the wavefront and the transmission paths in different incident OAM beams. Due to the presence of spin angular momentum (SAM), the vortex beam to be identified is spatially separated after passing through the metasurface. As a proof of concept, 14 signal channels are considered in the constructed metasurface, 12 of them can be encoded at will for the detection of any vortex beam with a predefined topological charge. These results make use of metasurfaces to enable OAM pattern recognition in an effective way, which may open avenues for the ultimate miniaturization of optical vortex communication and advanced OAM detection technologies.

A Study on Anti-Jamming Algorithms in Low-Earth-Orbit Satellite Signal-of-Opportunity Positioning Systems for Unmanned Aerial Vehicles

Low-Earth-Orbit (LEO) satellite Signal-of-Opportunity (SOP) positioning technology has gradually matured to meet the accuracy requirements for unmanned aerial vehicle (UAV) positioning in daily scenarios. Advancements in miniaturization technology for positioning terminals have also made this technology’s application to UAV positioning crucial for UAV development. However, in the increasingly complex electromagnetic environment, there remains a significant risk of degradation in positioning performance for UAVs in LEO satellite SOP positioning due to unintentional or malicious jamming. Furthermore, there is a lack of in-depth research from scholars both domestically and internationally on the anti-jamming capabilities of LEO satellite SOP positioning technology. Due to significant differences in the downlink signal characteristics between LEO satellites and Global Navigation Satellite System (GNSS) signals based on Medium Earth Orbit (MEO) or Geostationary Earth Orbit (GEO) satellites, the anti-jamming research results of traditional satellite navigation systems cannot be directly applied. This study addresses the narrow bandwidth and high signal-to-noise ratio (SNR) characteristics of signals from LEO satellite constellations. We propose a Consecutive Iteration based on Signal Cancellation (SCCI) algorithm, which significantly reduces errors during the model fitting process. Additionally, an adaptive variable convergence factor was designed to simultaneously balance convergence speed and steady-state error during the iteration process. Compared to traditional algorithms, simulation and experimental results demonstrated that the proposed algorithm enhances the effectiveness of jamming threshold settings under narrow bandwidth and high-power conditions. In the context of LEO satellite jamming scenarios, it improves the frequency-domain anti-jamming performance significantly and holds high application value for drone positioning.

A MIMO-Based Dual Polarized Antenna Applicable for Mobile Terminal

At present, numerous small-size mobile terminal devices, such as mobile phones, have embedded the antenna in the cases, which will lead to considerable restrictions on the space for installing multiple antennas. Aiming at the requirements of rational design and layout of multi-antennas for MIMO mobile terminals and combining with the broadband and miniaturization technologies, a dual polarized antenna suitable for mobile terminals was designed in this paper through an adoption of polarization diversity. For a dual polarized multilayered micro-strip antenna with a ground plate, it is easy to be conformal to the carrier. In this paper, the design and the process of simulation optimization of the antenna unit were analyzed in detail. The bandwidth of the antenna unit was 1890 to 2200 MHz, the return loss was superior to -33dB, and both of the horizontal polarization gain and the vertical polarization gain were 8.2 dB. Accordingly, the characteristics of a high gain and dual polarization were achieved.

Analytical approach to piezoelectric model synthesis with the use of Cauer’s method for system design

Background Piezoceramic materials have unique property which enables direct and bilateral conversion between mechanical and electrical energy. This ability facilitates significant miniaturisation of technology and opens many opportunities in design of new actuators and energy harvesters. Mathematical modelling of piezoelectric modules is notoriously hard due to complex constitutive equations defining mechanical and electrical energy conversion. Methods The article presents research on a new synthesis method based on the Cauer’s method. Mechanical damping is introduced with the use of Rayleigh’s approximation. A discrete electromechanical model is formed based on the Mason’s piezoelectric model. The proposed approach allows modelling of piezoelectric systems based on a set of characteristic frequencies. The method allows a more general approach to the problem of modelling new systems, as opposed to application-oriented methods seen in literature. A non-standard model analysis method using edge graphs and structural numbers is also verified as a potential alternative for matrix-based method. The authors compare their precision and computation requirements. Results The structural method of mechanical model analysis gave identical results as the reference matrix method. However, the non-classical algorithm took much longer to calculate and was using more memory. The electromechanical model analysis has shown an error of 5% in comparison to resonance frequencies taken from a reference plate specification. The calculated magnitude of displacement was well above the capability of a 3.5mm thick piezoelectric plate. Conclusions The synthesis method presented in this paper allows synthesizing piezoelectric cascade models based on limited information in form of characteristic frequencies. Currently this method allows a coarse approximation of the real piezoelectric parameters with limited number of inputs. The additional method of analysis based on structural numbers offers a promising alternative to matrix calculations but requires a more thorough investigation of the computational power required to determine whether it can compete with existing algorithms.

A Robust Track Estimation Method for Airborne SAR Based on Weak Navigation Information and Additional Envelope Errors

As miniaturization technology has progressed, Synthetic Aperture Radar (SAR) can now be mounted on Unmanned Aerial Vehicles (UAVs) to carry out observational tasks. Influenced by airflow, UAVs inevitably experience deviations or vibrations during flight. In the context of cost constraints, the precision of the measurement equipment onboard UAVs may be relatively low. Nonetheless, high-resolution imaging demands more accurate track information. It is therefore of great importance to estimate high-precision tracks in the presence of both motion and measurement errors. This paper presents a robust track estimation method for airborne SAR that makes use of both envelope and phase errors. Firstly, weak navigation information is employed for motion compensation, which reduces a significant portion of the motion error. Subsequently, the track is initially estimated using additional envelope errors introduced by the Extended Omega-K (EOK) algorithm. The track is then refined using a phase-based approach. Furthermore, this paper presents the calculation method of the compensated component for each target and provides an analysis of accuracy from both theoretical and simulation perspectives. The track estimation and imaging results in the simulations and real data experiments validate the effectiveness of the proposed method, with an estimation accuracy of real data experiments within 5 cm.

A Systematic Analysis of Wearable Devices as Brain-Computer Interface Based on Neuromodulation

As the global health landscape deteriorates, the imperative of ensuring our well-being becomes increasingly apparent. The evolution of integrated circuit miniaturization technology has propelled the advancement of brain-computer interfaces to the forefront of research. Breakthroughs in recording and stimulating deep brain activity in humans have paved the way for a groundbreaking healthcare delivery method, referred to as the "Neural Stack" – a wearable medical device leveraging neuromodulation. This innovation contributes significantly to both the development of brain-computer technology and the broader field of neuroscience. In this article, the author delve into recent milestones within the realm of brain-computer interfaces, dissecting the associated challenges and envisioning future developments and applications. Given the interdisciplinary nature of brain-computer technology, contemporary scholars in the new era are compelled to explore and comprehend its intricacies. We are on the brink of an era where all things are interconnected, with brain-computer interfaces serving as the conduit for information exchange.

An actively stabilized, miniaturized epi-fluorescence widefield microscope for real-time observation in vivo.

Recent developments in real-time, in vivo micro-imaging have allowed for the visualization of tissue pathological changes, facilitating rapid diagnosis. However, miniaturization, magnification, the field of view, and in vivo image stabilization remain challenging factors to reconcile. A key issue for this technology is ensuring it is user friendly for surgeons, enabling them to use the device manually and obtain instantaneous information necessary for surgical decision-making. This descriptive study introduces a handheld, actively stabilized, miniaturized epi-fluorescence widefield microscope (MEW-M) for real-time observation in vivo with high resolution. The methodology of MEW-M system includes high resolution microscopy miniaturization technology, thousandfold shaking suppression (actively stabilized), ultra-photosensitivity, and tailored image signal processing cell image capture and processing technology, which support for the excellent real-time imaging performance of MEW-M system in brain, mammary, liver, lung, and kidney tissue imaging of rats in vivo. With a single-objective and high-frame-rate imaging, the MEW-M system facilitates roving image acquisition, enabling contiguous analysis of large tissue areas. RESEARCH HIGHLIGHTS: A handheld, actively stabilized MEW-M system was introduced. Excellent real-time, in vivo imaging with high resolution and active stabilization in brain, mammary, liver, lung, and kidney tissue of rats.

Drug testing of monodisperse arrays of live microdissected tumors using a valved multiwell microfluidic platform.

Cancer drug testing in animals is an extremely poor predictor of the drug's safety and efficacy observed in humans. Hence there is a pressing need for functional testing platforms that better predict traditional and immunotherapy responses in human, live tumor tissue or tissue constructs, and at the same time are compatible with the use of mouse tumor tissue to facilitate building more accurate disease models. Since many cancer drug actions rely on mechanisms that depend on the tumor microenvironment (TME), such platforms should also retain as much of the native TME as possible. Additionally, platforms based on miniaturization technologies are desirable to reduce animal use and sensitivity to human tissue scarcity. Present high-throughput testing platforms that have some of these features, e.g. based on patient-derived tumor organoids, require a growth step that alters the TME. On the other hand, microdissected tumors (μDTs) or "spheroids" that retain an intact TME have shown promising responses to immunomodulators acting on native immune cells. However, difficult tissue handling after microdissection has reduced the throughput of drug testing on μDTs, thereby constraining the inherent advantages of producing numerous TME-preserving units of tissue for drug testing. Here we demonstrate a microfluidic 96-well platform designed for drug treatment of hundreds of similarly-sized, cuboidal μDTs ("cuboids") produced from a single tumor sample. The platform organizes a monodisperse array of four cuboids per well in 384 hydrodynamic traps. The microfluidic device, entirely fabricated in thermoplastics, features 96 microvalves that fluidically isolate each well after the cuboid loading step for straightforward multi-drug testing. Since our platform makes the most of scarce tumor tissue, it can potentially be applied to human biopsies that preserve the human TME while minimizing animal testing.

Surface scattering-dependent electronic transport in ultrathin scandium nitride films

With the constant miniaturization of device technologies, it has become essential to understand and engineer the electronic properties of semiconductors in nanoscale dimensions. Scandium nitride (ScN), an emerging rock salt indirect bandgap semiconductor, has attracted significant interest for its interesting thermoelectric, plasmonic, neuromorphic computing, and Schottky barrier device applications. However, an in-depth understanding of the electronic transport, carrier scattering mechanism, and optical properties in ultrathin ScN films is still missing. Here, we show surface-scattering dominant electronic transport in epitaxial ScN films at nanoscale thicknesses. At the ultrathin dimensions, surface scattering increases significantly due to the large surface-to-volume ratio and growth-induced texturing. As a result, mobility decreases, and resistivity increases drastically with decreasing film thickness. Temperature-dependent electronic transport shows that the mobility of the ultrathin films decreases with increasing temperature due to the ionized-impurity and dislocation scattering. Electronic transport properties are further rationalized with x-ray diffraction and pole-figure analysis that shows that while the ultrathin films maintain their predominant 002 texture, their quality degrades with decreasing thickness. However, no significant changes are observed in the electronic structure of the films, as evidenced by x-ray photoelectron spectroscopy, photoemission measurements, and first-principles density functional theory calculations. Our results elucidate the impact of surface scattering on the ultrathin ScN films and would lead to miniaturized devices with improved efficiencies.

Analytical approach to piezoelectric model synthesis with the use of Cauer’s method for system design

Background: Piezoceramic materials have unique property which enables direct and bilateral conversion between mechanical and electrical energy. This ability facilitates significant miniaturisation of technology and opens many opportunities in design of new actuators and energy harvesters. Mathematical modelling of piezoelectric modules is notoriously hard due to complex constitutive equations defining mechanical and electrical energy conversion. Methods: The article presents research on a new synthesis method based on the Cauer’s method for electrical and mechanical system design. Mechanical damping is introduced with the use of Rayleigh’s approximation. A discrete electromechanical model is formed based on the Mason’s piezoelectric model. As an additional element of the research, a non-standard model analysis method using edge graphs and structural numbers is employed to investigate potential reductions in computational requirements for model analysis. Results: The electromechanical model analysis has shown an error of 5% in relation to the resonance target. The calculated peak in magnitude of displacement at the resonant frequency was well above the capability of a 3.5mm thick piezoelectric plate. The proposed non-standard method of analysis gave identical results in terms of obtained resonance frequencies. The calculated magnitude of vibrations was varying by 50 – 58%. Conclusions: The synthesis method presented in this paper allows an approximation of piezoelectric parameters of a real system based on the created mathematical model. Currently this method is subject to a considerable error in the determined vibration amplitudes of the system, but it allows a coarse approximation of the parameters while having a very limited number of input data. The additional method of analysis based on structural numbers offers a promising alternative to matrix calculations but requires a more thorough investigation of the computational power required to determine whether it can compete with existing algorithms.

New structure-performance relationships for surface-based lattice heat sinks

Heat sinks have manifold applications, from micro-electronics to nuclear fusion reactors. Their performance expectations will continue to increase in line with the power consumption and miniaturisation of technology. Additive manufacturing enables the creation of novel, compact heat sinks with greater surface-to-volume ratios and geometrical complexities than standard pin/fin arrays and pipes. Despite this, there has been little research into the use of high surface area lattice structures as heat sinks. Here, the hydraulic and thermal performance of five surface-based lattice structures were examined numerically. Computational fluid dynamics was used to create useful predictive models for pressure drop and volumetric heat transfer coefficients over a range of flow rates and volume fractions, which can henceforth be used by heat transfer engineers. The thermal performance of surface-based lattices was found to be heavily dependent on internal geometry, with structures capable of distributing thermal energy across the entire fluid volume having greater volumetric heat transfer coefficients than those with only localised areas of high heat transfer and low levels of fluid mixing.

Optimal use of electric propulsion for drag compensation in very low earth orbit on satellites with deployable solar panels

In recent years, thanks to advancements in commercial hardware technology miniaturization, small satellites have become more and more important and effective in the Space ecosystem. In previous papers it has been demonstrated that future smallest observation systems, operating at a lower altitude than traditional systems, have the potential for comparable or better performance, much lower overall mission cost, lower risk, shorter schedules, lower up-front development cost, more sustainable business model, mitigating the problem of orbital debris. Flying in very low Earth orbit requires the addition of a propulsion system capable of providing drag compensation. Thanks to its high specific impulse, electric propulsion is potentially well suited for this task. However, the use of an electric thruster often requires significant power that can be provided only with deployable solar panels. To minimize the drag, the solar panels should be aligned with the satellite orbital velocity. At the same time, to maximize the power input, the solar panel surfaces should point toward the Sun. In the majority of cases these two conditions are not met simultaneously, so an optimal trade-off is needed. This topic is investigated in this paper by the use of an orbital model of a generic satellite with deployable solar panels. The model is able to simulate any circular orbit of the satellite in any day of the year and calculate both the power input and the drag from the solar panels based on their inclination. An equivalent specific impulse is also defined taking into account the thrust that the electric thruster has to provide only to push the area of the solar panels required to power the propulsion system. The results show, as expected, that the sun-synchronous Dawn-Dusk (or Dusk-Dawn) orbit is the preferred one for the electric propulsion as the velocity vector and the Sun vector are almost orthogonal. In the other cases, at very low Earth orbit, even relatively small inclinations of the solar panels respect to the velocity vector have a significant impact on the drag produced, increasing the propellant consumption and the required power. Nevertheless, it is shown also that if the solar panels are aligned with the velocity, the power lost can be kept reasonable. The same analysis could also apply to a satellite in low Earth orbit that does not employ an electric thruster but still needs deployable solar panels because of other sources of high power consumption (e.g. the payload).

Reversing A Decades‐Long Scaling Law of Dielectric Breakdown using Hydrogen‐Plasma‐Treated HfO2 ReRAM Devices

AbstractDielectric breakdown (BD) is known to cause component failure in electronic devices and high‐voltage power lines over many decades. In recent years, this failure mechanism has been exploited to intentionally form nanoscale filaments in resistive random‐access‐memory (ReRAM) devices for artificial intelligence (AI). The statistical nature of this failure mechanism, known as the inverse size scaling law based on the weakest‐link theory, dictates the ever‐higher forming voltages for ReRAM devices, in turn, requiring additional peripheral transistors. This law also causes diminishing lifetimes of electronic components for future generations of very‐large‐integrated circuits (VLSI) technology. Currently, the semiconductor industry faces these scaling barriers limiting the miniaturization of both VLSI and AI hardware technology. Here, experimental evidence of a reverse area dependence is presented by introducing an innovative fabrication process with a hydrogen‐plasma‐treated layer in a bilayer HfO2 structure. Using joint order statistics rather than traditional extreme‐value statistics, a physics‐based statistical model is developed in agreement with the experimental data, thus demonstrating that there is no fundamental reason preventing this law from being reversed or altered. These findings will have a significant impact on both technology scaling and fabrication innovation for electronic and/or bioinspired nanomaterials; moreover, stimulate much research in physics, statistics, and reliability.

Fabrication of waveguide directional couplers using 2-photon lithography.

Advances in 2-photon lithography have enabled in-lab production of sub-micron resolution and millimeter scale 3D optical components. The potential complex geometries are well suited to rapid prototyping and production of waveguide structures, interconnects, and waveguide directional couplers, furthering future development and miniaturization of waveguide-based imaging technologies. System alignment is inherent to the 2-photon process, obviating the need for manual assembly and allowing precise micron scale waveguide geometries not possible in traditional fused fiber coupler fabrication. Here we present the use of 2-photon lithography for direct printing of multi-mode waveguide couplers with air cladding and single mode waveguide couplers with uncured liquid photoresin cladding. Experimental results show reproducible coupling which can be modified by selected design parameters.

Enhancing predictability of thermal warpage by applying temperature-dependent Poisson's ratio of epoxy molding compound

The warpage behavior of electronic packages has become complicated in recent years owing to the miniaturization and heterogeneous integration technologies. Therefore, stress analyses through warpage simulations have become increasingly challenging. Understanding the thermo-mechanical behavior of epoxy-based packaging materials enhances the predictability of warpage simulation and helps in designing mechanically reliable electronic packages. However, the necessity and importance of an accurate database of thermo-elastic properties, especially the temperature dependency of Poisson's ratio, still has been overlooked for warpage prediction. In this study, the warpage prediction accuracy of a molded wafer was dramatically improved by measuring and applying the temperature dependency of elastic modulus and Poisson's ratio. If the temperature dependency of Poisson's ratio and elastic modulus is not considered, the warpage prediction error increases by 4.3 and 8.1 times for the 25 °C and 250 °C warpage, respectively. Surprisingly, even without considering only the temperature dependency of Poisson's ratio, the prediction error increased by 3.3 and 4.4 times for the 25 °C and 250 °C warpage, respectively. These results indicate that Poisson's ratio significantly affects the coefficient of thermal expansion-induced warpage behavior in the form of the biaxial modulus.

Magnetic cleanliness verification of miniature satellites for high precision pointing

The advancement in miniature satellite technology and its increasing usage in scientific and commercial applications presents new and unique challenges, particularly for pointing requirements. These small platforms, often limited in resources, are particularly susceptible to disturbance from residual magnetic dipoles while operating in low earth orbit (LEO). To overcome this issue, the precise identification of a satellite's residual magnetic dipole is crucial to enable the compensation of disturbance torques. However, the use of magnetic materials in modern commercial-off-the-shelf (COTS) technology cannot always be avoided. The pre-launch verification of magnetic cleanliness requirements in a laboratory setting is also a significant challenge for small satellite systems. To address this problem, Fraunhofer Ernst-Mach-Institute (EMI) and Fraunhofer Institute for Physical Measurement Techniques (IPM) have developed a cutting-edge test setup for the precise characterization of small residual dipole moments, with the goal of qualifying the ERNST nanosatellite. This innovative approach aims to provide efficient system verification with minimal time and cost overhead and to establish a dedicated test infrastructure, specifically tailored to tackle the unique challenges and requirements of magnetic cleanliness verification in future miniature space systems. As a promising preliminary result of the first test campaign, the filter wheel mechanism of the ERNST nanosatellite could be optimized, resulting in a significantly reduced magnetic moment of the device, meeting the missions challenging magnetic budget constraints.

Electromigration in three-dimensional integrated circuits

The development of big data and artificial intelligence technology is increasing the need for electronic devices to become smaller, cheaper, and more energy efficient, while also having enhanced functionalities. However, the miniaturization of silicon chip technology is approaching its Moore's law (i.e., physical) limits. Thus, the application of three-dimensional integrated circuits (3D ICs), in which multiple chips are stacked vertically, provides the most achievable approach for the advancement of post-Moore electronics. In the recent decade, various key techniques have been developed for stacking chips vertically such as through-silicon vias, micro-bumps, low melting point tin–bismuth solders, redistribution layers, and copper-to-copper direct bonding. However, the need for high current densities in these structures results in severe Joule heating, making electromigration (EM) an increasingly challenging problem. This paper reviews studies on EM failures, mechanisms, and potential solutions for the key components of 3D IC packaging.

Atomic Layer Etching Using a Novel Radical Generation Module.

To fabricate miniature semiconductors of 10 nm or less, various process technologies have reached their physical limits, and new process technologies for miniaturization are required. In the etching process, problems such as surface damage and profile distortion have been reported during etching using conventional plasma. Therefore, several studies have reported novel etching techniques such as atomic layer etching (ALE). In this study, a new type of adsorption module, called the radical generation module, was developed and applied in the ALE process. Using this module, the adsorption time could be reduced to 5 s. Moreover, the reproducibility of the process was verified and an etch per cycle of 0.11 nm/cycle was maintained as the process progressed up to 40 cycles.