Miniature Structures Research Articles

Design implementation analysis of multi-band antenna for terrestrial applications

A multi-band antenna is proposed for terrestrial applications above 5 GHz. The design includes one director element, three split ring resonators (SRR), and a printed patch antenna on a FR4 substrate to make the miniature structure. The novelty is the addition of “C” split rings and one identical stub linked to the partial ground into the radiating element, which improves impedance matching and radiation characteristics across the target bands. The prototype is designed with five distinct resonance frequencies and radiation patterns compared to those produced by the patch, the director and resonators are added. Return loss simulation results and measured radiation pattern findings are validated and analyzed. The antenna produces a gain of 7.84 dB, overall efficiency of 84.76 %, and a VSWR of 1.8 at 7 GHz frequency, which is achieved due to the peculiar features of the FR4 and it is highly suitable for traditional communication. VSWR, gain, and radiation efficiency are all higher on this antenna than they are on a typical multiband antenna. At 20 GHz, the designed antenna band is efficient to operate with five dissimilar resonant frequency bands, pinpointed at 7.224 GHz, 10.723 GHz, 13.808 GHz, 17.014 GHz and 19.549 GHz through different impedance bandwidths.

Developments of Waveguide Lasers by Femtosecond Laser Direct–Writing Technology

Waveguide lasers have the advantages of miniature and compact structure and have broad application prospects in photonic integration and on–chip laboratories. The development of femtosecond laser direct–writing technology makes the processing of transparent materials more flexible and controllable. This paper mainly introduces a waveguide laser based on femtosecond laser direct–writing technology. Firstly, the applications of femtosecond laser direct–writing technology in an optical waveguide are introduced, including the principles of femtosecond laser direct–writing technology, common optical wave scanning methods, and types of optical waveguides. After that, we summarize the development of a waveguide continuous–wave laser, a Q–switched laser and a mode–locked laser from visible to mid–infrared wavebands and analyze some new representative work. Finally, we explain the difficulty of compensating for dispersion in pulse waveguide lasers and summarize some new ideas that have been proposed to solve the problem.

Miniature fiber optic SPR high sensitivity humidity sensor based on coated polyvinyl alcohol film

For the measurement of relative humidity, this study employed Surface Plasmon Resonance (SPR) technology, a sensor with a micro-conical fiber structure (sensing length is only 375 μm) was combined with Polyvinyl Alcohol (PVA) to create a humidity sensor that is highly sensitive, compact, dense, and exhibits good linearity. The humidity sensor is based on a gold film (thickness of about 40 nm) on the surface of the miniature fiber optic structure, and by applying PVA coating, the SPR humidity sensor shows resonance peaks in the transmission spectrum in ambient air, and as the number of layers of PVA coating (thickness) is added, the resonance peaks’ positions are red-shifted. The experimental findings demonstrated that this SPR humidity sensor’s sensitivity was 0.162 nm/%RH at an initial resonance wavelength of about 550 nm (one layer) and about 1.542 nm/%RH at an initial resonance wavelength of 656 nm (five layers) in the range of 46 %RH to 93 %RH. The wavelength and the relative humidity had a good linear connection. Temperature tests revealed the sensor has a −0.152 nm/°C temperature sensitivity between 20 °C and 50 °C and has a high linearity (0.999). Therefore, the sensor has potential applications in humidity measurement.

High-Sensitivity Curvature Fiber Sensor Based on Miniature Two-Path Mach-Zehnder Interferometer.

This paper introduces a new high-sensitivity curvature fiber sensor based on a miniature two-path Mach-Zehnder interferometer (MTP-MZI). The sensor is fabricated by coupling and fusing the multimode fiber (MMF) with the single-mode fiber (SMF) using arc fusion technology (AFT), resulting in a centimeter-level two-path MZI structure. The sensor represents an innovative approach to MZI coupling technology, which reduces device size, simplifies manufacturing, and lowers costs. In curvature-sensing experiments, the MTP-MZI sensor achieves a maximum curvature sensitivity of -96.70 dB/m-1 in the curvature range of 0.0418 m-1 to 0.0888 m-1, which is an extremely high sensitivity among intensity-modulated curvature sensors. Additionally, temperature-sensing measurements of the MTP-MZI sensor show a maximum temperature sensitivity of 212 pm/°C in the range of 30 °C to 70 °C, which is low temperature sensitivity and solves the cross-sensitivity problem. Thanks to the miniature two-path structure of the MTP-MZI, it provides a new perspective for developing multidimensional and multiparameter measurement methods in MZI fiber sensors.

Demonstration of proton acceleration using laser-driven EMP field in dispersion-free slow wave tube

We demonstrate the laser-driven post-acceleration experiment, utilizing a miniature slow-wave structure. Experiments on a terawatt laser system showed a significant increase in proton cutoff energy, highlighting the technique's potential, especially for high-power laser systems. The slow-wave structure consists of a helix and a shielded metallic shell covered on the outside. The transmission properties of electromagnetic pulses (EMPs) generated by laser–foil interactions along the structure are studied. Through an electromagnetic field perspective, we derived dispersion relations for helices with and without metallic shield. Our findings, supported by theory, simulations, and experiments, demonstrate the structure's ability to transmit high-frequency EMPs with limited dispersion.

Numerical study on heat transfer deterioration of supercritical CO2 in lattice structure array channel

This study numerically explores the fluid flow and heat transfer features of supercritical carbon dioxide (CO2) in lattice structure array channel. The mitigation mechanism of the miniature cylindrical lattice structure array on heat transfer deterioration (HTD) of supercritical CO2 in vertically upward heated channel is studied. This paper evaluates the effect of several key influential parameters (length, diameter, pitch and number) of cylindrical lattice structure array on fluid flow field involving vortex structures, heat transfer coefficient, buoyancy effect and accelerated effect. The results indicate that the lattice structure can effectively suppress the HTD by generating the vortex structure which promoting the turbulent mixing effect and enhancing the turbulent kinetic energy (TKE) of the fluid. Compared with the smooth channel, the peak wall temperature of the lattice structure channel is reduced by about 50 °C, with a corresponding increase in the heat transfer coefficient of about 140 %. The average heat transfer coefficient of the channel is increased by more than 1/3. Furthermore, by increasing lattice length can reduce flow layer stratification and by increasing lattice diameter can creating a composite vortex, which enhance flow mixing strength. The larger the lattice pitch, the worse the overall suppression effect. A denser lattice arrangement produces more temperature valleys, thereby increasing the heat transfer coefficient. The conclusions in this study could provide the main theory support for security and stability of supercritical CO2 heat exchangers in power system.

A Micro-Mach–Zehnder Interferometer Temperature Sensing Design Based on a Single Mode–Coreless–Multimode–Coreless–Single Mode Fiber Cascaded Structure

In this paper, a temperature sensing scheme with a miniature MZI structure based on the principle of inter-mode interference is proposed. The sensing structure mainly comprises single mode–coreless–multimode–coreless–single mode fibers (SCMCSs), which have been welded together, with different core diameters. The light beam has been expanded after passing through the coreless optical fiber and is then coupled into a multimode optical fiber. Due to the light passing through the cladding and core mode of the multimode optical fiber with different optical paths, a Mach–Zehnder interferometer is formed. Moreover, due to the thermo-optic and thermal expansion effects of optical fibers, the inter-mode interference spectrum of a multimode fiber shifts when the external temperature changes. Through theoretical analysis, it is found that the change in the length of the sensing fiber during temperature detection has less of an effect on the sensitivity of the sensing structure. During the experiment, temperature changes between 20 and 100 °C are measured at sensing fiber lengths of 1.5 cm, 2.0 cm, 2.5 cm, 3.0 cm, 3.5 cm, and 4.0 cm, respectively, and the corresponding sensitivities are 65.98 pm/°C, 72.70 pm/°C, 67.75 pm/°C, 66.63 pm/°C, 74.80 pm/°C, and 72.07 pm/°C, respectively. All the corresponding correlation coefficients are above 0.9965. The experimental results indicate that in the case of a significant change in the length of the sensing fiber, the sensitivity of the sensing structure changes slightly, which is consistent with the theory that the temperature sensitivity is minimally affected by a change in the length of the sensing fiber. Therefore, the effect of the length on sensitivity in a cascade-based fiber structure is well solved. The sensing scheme has an extensive detection range, small size, good linearity, simple structure, low cost, and high sensitivity. It has a good development prospect in some detection-related application fields.

Optimization of swash plate multistage compressor based on dynamics

The swash plate compressor can provide high-pressure gas through multistage compression using its different cylinders, which is an ideal structure for high-pressure compressor miniaturization. The swash plate multistage compressor (SPMC) with variable sections cylinder and inter-stage cooler is proposed and its complex structure results in complex multi-body dynamics and thermodynamics. To research the dynamic characteristics of SPMC, the dynamic model of SPMC is established, which includes the thermodynamics of compression and inter-stage cooler and the dynamics of all the check valves and pistons. The optimization objective function considering the dynamic characteristics and efficiency is proposed. The constraint conditions and sensitivity of the optimized parameters are studied and the final parameters are achieved through an optimization algorithm. Based on the above work, it can be found that the optimization way has high convergence and accuracy, and the comprehensive performance of SPMC is improved significantly.

Brain Organoids, the Path Forward?

Brain Organoids, the Path Forward?

Bronchioalveolar organoids: A preclinical tool to screen toxicity associated with antibody-drug conjugates

Despite extensive preclinical testing, cancer therapeutics can result in unanticipated toxicity to non-tumor tissue in patients. These toxicities may pass undetected in preclinical experiments due to modeling limitations involving poor biomimicry of 2-dimensional in vitro cell cultures and due to lack of interspecies translatability in in vivo studies. Instead, primary cells can be grown into miniature 3-dimensional structures that recapitulate morphological and functional aspects of native tissue, termed “organoids.” Here, human bronchioalveolar organoids grown from primary alveolar epithelial cells were employed to model lung epithelium and investigate off-target toxicities associated with antibody-drug conjugates (ADCs). ADCs with three different linker-payload combinations (mafodotin, vedotin, and deruxtecan) were tested in bronchioalveolar organoids generated from human, rat, and nonhuman primate lung cells. Organoids demonstrated antibody uptake and changes in viability in response to ADC exposure that model in vivo drug sensitivity. RNA sequencing identified inflammatory activation in bronchioalveolar cells in response to deruxtecan. Future studies will explore specific cell populations involved in interstitial lung disease and incorporate immune cells to the culture.

Influence of bionic structure on hydraulic performance and drag reduction effect of a centrifugal pump

Based on bionic theory, miniature dimple-type structures are constructed on the blades of a single-stage centrifugal pump to investigate the influence of the bionic structures on the hydraulic performance and drag reduction effect of the pump. The results show that dimples with shallower depth and which are located near the front section of the blade suction surfaces are more effective in improving the efficiency and reducing the drag of the pump. At small flow rate, due to the mismatch between the incoming flow angle and the blade placement angle, serious flow separation occurs in several flow channels, accompanied by the formation of the vortices, which would deteriorate the performance of the pump. With the arrangement of the dimples on blade suction surfaces, some low-speed vortices formed in the dimples, which is equivalent to increasing the effective thickness of the viscous substrate layer and decreasing the velocity gradient of the boundary layer. Therefore, the velocity distribution in the flow channels gets more uniform, and the turbulence kinetic energy and wall shear stress are thereby reduced.

Histological Observation of Helmet Development in the Treehopper Poppea capricornis (Insecta: Hemiptera: Membracidae).

The treehoppers (Hemiptera, Membracidae) are known for possessing a large three-dimensional structure called a helmet. Although some ecological functions of the helmet have already been elucidated, the developmental mechanisms underlying the complex and diverse morphology of the helmet are still largely unknown. The process of helmet formation was first described in Antianthe expansa, which possesses a simple roof-shaped helmet. However, the developmental process in species with more complex helmet morphologies remains largely unexplored. Hence, in this study, we used Poppea capricornis, which possesses a more complex helmet structure than A. expansa, to investigate the helmet development using paraffin sections, micro-CT, and scanning electronic microscopy. Our focus was on the overall helmet developmental process common to both species and formation of structures unique to Poppea and its comparison to Antianthe. As a result, we discovered that miniature structures were also formed in Poppea, similar to Antianthe, during the helmet formation. Common structures that were shared between the two species were discernible at this stage. Additionally, we observed that suprahumeral horns and posterior horns, two morphological traits specific to the Poppea helmet that are apparently similar anatomically, are formed through two distinctly different developmental mechanisms. The suprahumeral horns appeared to be formed by utilizing the nymphal suprahumeral bud as a mold, while we could not detect any nymphal structures potentially used for a mold in the posterior horns formation. Our findings suggest that the helmet formation mechanisms of Antianthe and Poppea employ a common mechanism but form species-specific structures by multiple mechanisms.

Broadband beam deflector for GaN based micro-LED with a phase-gradient metasurface in entire visible spectrum

Metasurfaces with subwavelength structures are good candidates for beam manipulation which are usually working at a narrow bandwidth with high coherence. Here, we demonstrate a broadband beam deflector for GaN based micro-LED, utilizing a phase-gradient metasurface in conjunction with a resonant cavity. The beam deflector works at the entire visible spectrum, achieving deflection angles from 9° to 18°, with beam efficiencies of approximately 20% to 35%. This miniature structure is well-suited for applications such as full-color display, naked-eye three-dimensional display, and head-up display. It will facilitate the development of GaN based micro-LEDs with complex optical functionalities.

Determination of Enantiomeric Excess by Optofluidic Microlaser near Exceptional Point.

Enantiomeric excess (ee) is an essential indicator of chiral drug purification in the pharmaceutical industry. However, to date the ee determination of unknown concentration enantiomers generally involves two separate techniques for chirality and concentration measurement. Here, a whispering-gallery mode (WGM) based optofluidic microlaser near exceptional point to achieve the ee determination under unknown concentration with a single technique is proposed. Exceptional point induces the unidirectional WGM lasing, providing the optofluidic microlaser with the novel capability to measure chirality by polarization, in addition to wavelength-based concentration detection. The dual-parameters detection of optofluidic microlaser empowers it to achieve ee determination of various unknown enantiomers without additional concentration measurements, a feat that is challenging to accomplish with other methods. Featuring the sensitivity enhancement and miniature structure of the WGM sensors, the obtained chiroptical response of the present approach is ≈30-fold higher than that of the conventional optical rotation-based polarimeter, and the reagent consumption is reduced by three orders of magnitude.

Organoid intelligence: Integration of organoid technology and artificial intelligence in the new era of in vitro models

Organoid Intelligence ushers in a new era by seamlessly integrating cutting-edge organoid technology with the power of artificial intelligence. Organoids, three-dimensional miniature organ-like structures cultivated from stem cells, offer an unparalleled opportunity to simulate complex human organ systems in vitro. Through the convergence of organoid technology and AI, researchers gain the means to accelerate discoveries and insights across various disciplines. Artificial intelligence algorithms enable the comprehensive analysis of intricate organoid behaviors, intricate cellular interactions, and dynamic responses to stimuli. This synergy empowers the development of predictive models, precise disease simulations, and personalized medicine approaches, revolutionizing our understanding of human development, disease mechanisms, and therapeutic interventions. Organoid Intelligence holds the promise of reshaping how we perceive in vitro modeling, propelling us toward a future where these advanced systems play a pivotal role in biomedical research and drug development.

VASCULAR ARTERY SIMULATION MODEL FABRICATION FOR PRE-SURGERY KIT FOR STENT APPLICATION THROUGH 3D PRINTING

Thrombosis occurs of a blood clot in the vein and blocking blood flow. The formation of a clot within the artery is called arterial thrombosis. Due to arterial thrombosis, there are heart attacks and strokes that result in more than 17.9 million deaths worldwide each year. Covid-19, one of today's problems, further increases the mortality rate. The thrombosis mechanism includes factors coming from the blood and the vessel wall. This mechanism is based on local blood flow mechanisms and 3-dimensional (3D) vessel geometry. Microfluidics chip-based vascular models examine the interaction between blood and the vessel wall in vitro studies in thrombosis. Until now, the 3-dimensional geometry of the arteries and blood flow system of healthy or unhealthy individuals have not been fully modeled. In this study, a patient-specific occluded blood vessel model was obtained from computed tomography angiography (CTA) data, and miniature vascular structures were developed with a 3D printer. These structures were printed using Acrylonitrile Butadiene Styrene (ABS). 3D ABS samples were used in Polydimethylsiloxane (PDMS) based soft lithography molds to occur microfluidic systems containing miniaturized replicas of in vivo vessel geometries. A comprehensive simulation of stented vasculature was performed by flow analysis of artificial blood and cell culture by placing a commercial stent on PDMS-based models. This project has aimed to develop and characterize modules by creating microfluidic systems using 3D printers to examine the effects of stents placed in the patient's complex vascular system and to simulate operations before treatment and stent placement.

A new design method for miniature dual-resonance photoacoustic structure based on piezoelectric ceramics slice

We report a new design method for miniature dual-resonance photoacoustic (PA) structure, mainly consisting of a miniature T-type PA cell and a piezoelectric ceramics slice. Both the T-type PA cell and the piezoelectric ceramics slice have the resonance frequencies, and the resonance frequencies of the T-type PA cell and the piezoelectric ceramics slice exhibit the same variation pattern with size. It provides support for the design of miniature photoacoustic sensors. As an example, we developed a miniature dual-resonance photoacoustic sensor, the resonance frequency of the miniature T-type PA cell is matched with the natural frequency of the piezoelectric ceramics slice to achieve double resonance of the acoustic signal. The volume of the designed photoacoustic structure is only about 3.75 cubic centimeters. The performance of this system was evaluated through Methane detection. Experimental results show good linearity, the linear fitting R square is 0.9988. The minimum detectable limit of CH4 is calculated to be 542 ppb with an integration time of 217 s according to the Allan-Werle deviation analysis. The performance demonstrated a great potential for the design of miniature photoacoustic sensors.

A Wideband Dual-Polarized Tightly Coupled Array with Compact Size for 5G Millimeter-wave Mobile Devices

ABSTRACT A miniaturized dual-polarized smartphone antenna based on tightly coupled dipole array (TCDA), applying to 5 G millimeter-wave (mmW), is presented. The antenna element has a size of 2.94 mm × 3.05 mm × 0.94 mm and covers a bandwidth of 91.5% and 88.4% with VSWR＜2 for pol-x and pol-y, respectively. To achieve low cost, compact size, and reduce the number of ports, a specific miniature feeding structure, using Γ-shaped coupling probes, is applied. The proposed smartphone antenna consists of eight elements with a size of 23.8 mm × 3.5 mm × 0.94 mm. Experiments show that the TCDA can support a minimum realized gain of 9.51 dB and 9.07 dB for pol-x and pol-y, respectively, within 5 G mmW bands. To verify the design concept, TCDA is fabricated and measured, which achieves 60° scanning without grating lobes. The measurement results demonstrate that the proposed antenna is well suited for future 5 G mmW mobile phones.

Compound Odontoma: Diagnosis and treatment: Case report

Odontomas are asymptomatic benign odontogenic tumors, generally discovered fortuitously, or when a tooth failed to erupt. They are mainly composed of enamel and dentin, cement and pulp tissue can also be present in variable amounts. In 2005, the World Health Organization classified two main types of odontoma, an amorphous and irregular mass of calcified dental tissues as complex odontoma and multiple miniature tooth-like structures as compound odontoma. This article is a case presentation of a compound odontoma diagnosed for an eleven year old girl upon a routine radiography, making it a lesion of childhood /adolescence. A retro-alveolar radiography of the anterior maxilla revealed a radiopaque mass with prominent external margins surrounded by a thin radiolucent rim in close contact with the root of the permanent right central incisor. In this case a surgical excision of the lesion was performed in order to prevent any risk of root resorption for the tooth in close contact. The results achieved indicate that the early diagnosis of odontomas allows the adoption of a less complex and inexpensive treatment and ensures better prognosis. A histological evaluation is imperative in order to confirm the exact diagnosis of odontoma.

Synthesis and Printing Features of a Hierarchical Nanocomposite Based on Nickel–Cobalt LDH and Carbonate Hydroxide Hydrate as a Supercapacitor Electrode

The hydrothermal synthesis of a hierarchically organized nanocomposite based on nickel–cobalt carbonate hydroxide hydrate of composition M(CO3)0.5(OH)·0.11H2O (where M is Ni2+ and Co2+) and nickel–cobalt layered double hydroxides (NiCo-LDH) was studied. Using synchronous thermal analysis (TGA/DSC), it was determined that the material retained thermal stability up to 200 °C. The crystal structure of the powder and the set of functional groups in its composition were determined by X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR). The resulting hierarchically organized nanopowder was employed as a functional ink component for microplotter printing of an electrode film, which is an array of miniature planar structures with a diameter of about 140 μm, on the surface of a nickel-plated steel substrate. Using scanning electron microscopy (SEM), it was established that the main area of the electrode “pixels” represents a thin film of individual nanorods with periodic inclusions of larger hierarchically organized spherical formations. According to atomic force microscopy (AFM) data, the mean square roughness of the material surface was 28 nm. The electrochemical properties of the printed composite film were examined; in particular, the areal specific capacitance at different current densities was calculated, and the electrochemical kinetics of the material was studied by impedance spectroscopy. It was found that the electrode material under study exhibited relatively low Rs and Rct resistance, which indicates active ion transfer at the electrode/electrolyte interface.