The major challenge limiting the application of terahertz(THz) technology lies in the significant attenuation of THz waves loss of THz waves during free-space transmission arising from water vapor absorption and gas molecule scattering. Compared with free space propagation, low-loss and stable transmission of THz wave can be achieved through the waveguide. Waveguide transmission at low THz frequencies has attracted considerable attention, particularly at around 300 GHz (0.3 THz). Among the various types of THz waveguides, hollow waveguides offer a simple structure, ease of fabrication, low cost, and excellent transmission performance in the THz regime. Here, we design and fabricate a low-loss THz metal dielectric hollow waveguide based on polypropylene (PP) tubing, where an external silver film coated on the PP tube forms a leaky-type hollow waveguide structure. The linear transmission loss is measured to be 1.35 dB/m at 300 GHz. By optimizing this low-loss THz hollow waveguide, we achieve a far-field THz digital holographic (TDH) imaging recording configuration for the first time. To evaluate the imaging performance, different types of samples are measured. Experimental results for a plastic plate with aluminum strips validate a lateral resolution of ∼2.5 mm. The proposed method holds potential as a powerful tool for investigating spontaneous phenomena in the THz band.

The development of multi-spectral detection technology poses a serious threat to the survival of combat platforms. Inherent constraints render conventional static geometry architectures of adapting electromagnetic responses to frequency-dependent radar threats, limiting the practical application. A mechanically adjustable radar infrared compatible stealth superstructure based on Microcontroller Unit (MCU) closed-loop control is proposed. The structure integrates four functional layers - an infrared shielding layer (IRSL), a cross and concentric ring-shaped radar absorbing layer, and a bottom radar reflecting layer. And each layer was prepared on a flexible and transparent Polyethylene terephthalate (PET) substrate by magnetron sputtering and laser etching. The inter-layer air gap (0.5-20 mm) is adjusted by the MCU-driven closed-loop positioning platform, and the superstructure can continuously re-match the radar absorption band. By adjusting the unit size of the IRSL layer, the infrared emissivity is reduced to 0.31, and the overall structure achieves a visible light transmittance of more than 65%. It can achieve excellent absorbing bandwidth (2.69-18.0 GHz), relative bandwidth of 147.9%, and maximum reflection loss of -21.5dB. The design of symmetrical structure makes the overall incident angle reach 45° and still has excellent absorbing performance. The closed-loop positioning mechanism ensures repeatable sub-millimeter-level gap control, which can reliably characterize the gap-dependent spectral response. This research provides a new implementation path for stealth design in dynamic electromagnetic environment in related fields.

Exosomes, nanoscale extracellular vesicles (30-150 nm) that carry diverse biomolecules, hold immense promise as biomarkers for disease diagnostics and drug delivery. However, their isolation from complex biofluids is significantly challenged by co-existing contaminants and the limitations of conventional methods like ultracentrifugation and immunoaffinity capture. These techniques often suffer from large sample requirements, structural damage, critical subpopulations loss and compromised recovery or purity. To overcome these hurdles, we introduce an inertial-acoustic microfluidic platform for the non-destructive isolation of exosomes with intact subpopulations. This approach synergizes an inertial spiral microchannel with a tilted-angle standing surface acoustic wave (SSAW) field to achieve precise, size-based fractionation of particles across micron and submicron scales. Initially, micron-scale particles such as cellular debris are efficiently removed via Dean flow forces and inertial focusing. Subsequently, submicron contaminants, including microvesicles and protein aggregates are selectively eliminated through acoustofluidic trapping, while exosomes are retained with high subpopulation integrity. Applied to THP-1 cell culture supernatant, the method achieved a high isolation purity exceeding 95% with minimal sample input and maintained structural integrity. Most importantly, it enables the preservation of the full spectrum of native exosome subpopulations, thereby maintaining their inherent biological diversity. As a label-free and high-throughput technique, this inertial-acoustic isolation platform provides a reliable and effective tool to propel exosome-related biological research and clinical translation by ensuring the unbiased recovery of functionally diverse vesicle subsets.

The rapid development of multispectral detection technology poses a serious challenge to the survivability of weapons and equipment. However, traditional stealth materials have significant limitations in multi-spectral compatibility and conformality of complex surfaces. Therefore, the development of flexible multi-spectral camouflage skin (MCS) with high performance has become an inevitable direction to promote the development of the next generation of weapon equipment camouflage systems. This paper proposes a multi-layer optimization design based on multi-scale design to achieve infrared-radar and visual stealth at the same time. Firstly, a lightweight flexible composite foam based on polydimethylsiloxane (PDMS) was constructed, and hollow glass microspheres (HGM) were used as filling materials to optimize the impedance matching of the system and improve the incident efficiency of electromagnetism (EM) waves. Combined with the topology optimized by the enhanced adaptive genetic algorithm (EAGA), the skin exhibits an efficient absorption of 15.42 GHz (RL < -10 dB). Besides, the integration of the composite foam and the infrared shielding layer (IRSL) achieves ultralow infrared emissivity of 0.245. Moreover, by the modulation of self-adaptive photochromic layer, the target achieves outstanding visual stealth performance in different background environments. This study provides an efficient, integrated and easy-to-deploy solution for solving the stealth problem of ground platforms such as armored vehicles in multi-spectral detection environment, and provides a feasible scheme for the development of next-generation adaptive camouflage technology.

Efficient separation of cancer cells from whole blood is vital for early cancer diagnosis. However, disease progression often causes complications that reduce survival, such as cholangitis in liver cancer due to bile-duct compression, with Escherichia coli (E. coli) and Klebsiella as common pathogens. To address this, we developed a sheathless microfluidic sorter that integrates inertial focusing with surface acoustic wave (SAW) manipulation to simultaneously isolate cancer cells and bacteria. Specifically, we introduce a label-free, SAW-driven microfluidic platform that couples passive inertial focusing with active SAW manipulation to enable concurrent separation of cancer cells and bacteria; Cr/Au interdigital transducers (IDTs) are patterned on a 128° Y-cut LiNbO₃ substrate. The system first employs a contraction–expansion microchannel to achieve preliminary separation. Larger particles are then deflected by a slanted interdigital transducer (S-IDT), improving bacterial sorting purity. Small particles are enriched at the first outlet (purity > 96

The major challenge limiting the application of terahertz (THz) imaging quality lies in the significant attenuation of THz waves during free-space transmission. This attenuation arises primarily from water vapor absorption and gas molecule scattering. Compared with free space propagation, low-loss and stable transmission of THz wave can be achieved through the waveguide. Waveguide transmission at low THz frequencies has attracted considerable attention, particularly at around 300 GHz (0.3 THz). Among the various types of THz waveguides, hollow waveguides offer a simple structure, ease of fabrication, low cost, and excellent transmission performance in the THz regime. Here we present a low-loss THz metal dielectric hollow waveguide based on polypropylene (PP) tubing, where an external silver film coated on the PP tube forms a leaky-type hollow waveguide structure. The linear transmission loss is measured to be 1.35 dB/m at 300 GHz. By optimizing this low-loss THz hollow waveguide, we achieve a far-field THz digital holographic (TDH) imaging recording configuration for the first time. To evaluate the imaging performance, different types of samples are measured. Experimental results for a plastic plate with aluminum strips validate a lateral resolution of ∼2.5 mm. The proposed method holds potential as a powerful tool for investigating spontaneous phenomena in the THz band.

With the rapid development of modern detection technology, conventional single-band stealth materials are increasingly inadequate to meet the practical application demands of modern intelligent equipment. In this work, a novel flexible metamaterial was proposed and fabricated. By introducing nano-Fe3O4 particles into a polydimethylsiloxane ( PDMS) matrix, multiple loss mechanisms were constructed, and their synergistic effect with the metasurface enables a broad effective absorption bandwidth of 3.5-18 GHz. Benefiting from a symmetrical structural design, the metamaterial exhibits stable absorption over a wide incident angle (+/- 45 degrees). Additionally, the incorporation of nano-Fe3O4 enhances the mechanical properties of the dielectric layer, with tensile and compressive strengths reaching 1.71 MPa and 25.03 MPa, respectively. Furthermore, the integration of an infrared shielding layer (IRSL) reduces the infrared emissivity to 0.306. These properties are achieved with an ultra-thin thickness of only 2.28 mm, while the metamaterial retains excellent flexibility for conformal applications. The comprehensive performance integrating "thin, wide-band, flexible, and compatible" characteristics has been successfully realized. This study provides a new perspective for the structure-function collaborative design of radar-infrared compatible stealth materials and demonstrates significant application potential in fields such as morphing aircraft and unmanned aerial vehicles.

In order to meet the requirements of efficient flight over wide airspace and at high speeds, morphing aircraft have been gradually emerging as a new avenue for innovative developments in aeronautical systems. With the steady progress in multi-target detection capabilities, the development of radar-infrared multi-spectral stealth-compatibility flexible skinning has become essential to ensure optimum flight performance for morphing aircraft. In this context, the study proposes a novel multi-layered design for optimization, integrating micro-structure and macro-structure. Several electromagnetic wave attenuation mechanisms have been developed by embedding nanoparticles in a PDMS matrix combined with frequency selective metasurfaces. This approach has resulted in a flexible sandwich matrix with extraordinary mechanical properties (1.66 MPa tensile strength) and an ultra-wide absorption bandwidth (25.28 GHz, Reflection loss (RL) < -10 dB). In addition, by integrating the infrared shield layer (IRSL), radar-infrared compatible stealth was achieved with an emissivity as low as 0.26. The developed multi-layer composite structure not only solves the incompatibility of radar and infrared stealth, but also demonstrates excellent flexibility in the conformations. This research provides both the theoretical basis and the technical support for the innovative development of high-speed morphing aircraft.

This paper presents a switchable metamaterial based on a structured aqueous medium, which is an absorber/ reflector combining broadband switching capability and optical transparency. The proposed structure comprises an infrared shield layer (IRSL) and water-based radar switchable layers (WRSL). The significant switchable function between wideband absorptive states (12.44-28.72 GHz) and wideband reflective states (10-30 GHz) can be implemented by injecting and discharging purified water at normal incidence. Low infrared emissivity in the range of 3 similar to 14 mu m can be obtained by appropriately adjusting the filling ratio of the ITO film and pure water temperature. It is important to note that the broadband switchable characteristic of the proposed structure is still applicable at large incidence angles. The distribution of physical field and parametric analyses are presented to better understand the working mechanisms of water-based absorbers/reflectors from a specialized perspective. Finally, a prototype of the designed structure is also produced and validation tests are performed. The proposed metamaterial structures have excellent properties in the microwave, infrared and optical fields, which are expected to have important application prospects in electromagnetic modulation, multispectral stealth, electromagnetic compatibility and wireless communications.

Traditional metamaterial absorbers are limited by their static structures, making it challenging to dynamically and flexibly tune the absorption frequency of electromagnetic waves. To address this limitation, this article innovatively proposes a multifunctional and reconfigurable mechanically tunable honeycomb-structured metamaterial for multispectral compatible camouflage (MTHS-MC). It consists of three main structural layers: the mechanical structure layer (MSL) the infrared stealth layer (IRSS), and the color-changing layer (CCL). Its unique honeycomb-like mechanical structure enables flexible tuning of the absorption band through compressive geometric configuration. This design achieves controllable deformation of the honeycomb structure (with a deformation value reaching 323$\sqrt{3}$/15 mm). This reconfiguration mechanism differs fundamentally from traditional geometric optimization approaches, allowing real-time switching between dual absorption peaks at 7.66 GHz and 16.51 GHz. Simultaneously, the CCL adjusts its color in response to temperature variations, achieving visible-light camouflage. Experimental results show that this metamaterial can switch between two absorption peaks within the 0-20 GHz range, and achieve broadband absorption within the 30-100 GHz range. Additionally, it demonstrates an infrared emissivity of 0.292 in the 3-14 mu m wavelength band. This design enables dynamic switching between different absorption bands, making it highly efficient for practical applications in complex environments.

This study presents a novel piezoelectric energy harvester featuring a dual-L-shaped cantilever structure, which effectively overcomes the critical limitations of conventional piezoelectric energy harvesting technologies, including low output voltage and inadequate power density. The proposed device utilizes a recursively nested dual-L-shaped metallic beam design, with piezoelectric patches bonded to the upper inner surface of each beam and connected in series to maximize energy conversion efficiency. Under a base excitation of 0.5 g, Under open-circuit conditions the prototype delivers a peak voltage of 28.2 V and an RMS voltage of 10.6 V; its first and second resonance peaks are 12 Hz apart. At the optimum load it furnishes 0.96 mW and a resultant power density of 2.91 W g −1 m −2 . By integrating a two-degree-of-freedom lumped parameter model with electromechanical coupling analysis, experimental results validate its dual-band frequency response and high-voltage output characteristics. The harvester demonstrates exceptional power density and energy harvesting efficiency under low-intensity excitation. With advantages such as structural simplicity, ease of fabrication, high voltage output, compact footprint, and superior power density, this device holds significant potential for applications in wearable electronics, remote monitoring systems, and low-power microelectronic devices.

With the increasing prevalence of multi-band detection technologies, military equipment and weapons face heightened risks of exposure to enemy detectors, posing significant challenges to stealth capabilities. This paper proposes a multispectral stealth metamaterial (MSM) designed for cross-band stealth applications in laser, infrared, and radar domains. The device integrates a one-dimensional photonic crystal (1D-PC) and a radarabsorbing metamaterial (RAM), achieving a low specular reflectivity (average value of 0.25) across the 8-14 mu m range, over 98 % absorption at 10.6 mu m, and more than 90 % absorption efficiency within the 7.5-18 GHz radar band, while simultaneously suppressing high emissivity in the infrared band. A 10 x 10 cm2 sample was fabricated and tested, demonstrating the device's multispectral modulation performance. This work provides a novel approach to multispectral modulation and thermal radiation management, offering potential advancements in stealth technology.

In this work, a multilayer metamaterial with integrated radar and infrared (IR) stealth capabilities was developed. The dielectric layer was constructed using a silicon carbide nanowire (SiCnws) composite, providing both strong electromagnetic wave absorption and excellent thermal resistance. Thermogravimetric analysis revealed minimal mass loss below 750 degrees C, indicating the material's stability in high-temperature environments. Additionally, the metamaterial exhibited a reflection loss lower than -10 dB throughout the 2.42-30 GHz range, corresponding to an absorption efficiency above 90%. The synergy between the frequency selective surface resonance and the SiCnws layer's thermal insulation and IR shielding properties enabled effective dual-band stealth performance. These results suggest that the proposed metamaterial is highly suitable for advanced defense applications, such as stealth coatings on jet engine exhaust systems in military aircraft.

In this study, a composite substrate with adjustable dielectric properties was prepared, and its promising application in wearable medical device antennas was demonstrated. 3-Methacryloxypropyltrimethoxysilane (KH570) was used to modify titanium dioxide (TiO2) nano-powder, and the modified powder was blended with a mixture of polydimethylsiloxane (PDMS) and polytetrafluoroethylene (PTFE) under the action of anhydrous ethanol. The resulting polymer material had the advantages of hydrophobicity, softness, low loss, and a high dielectric constant. Meanwhile, the effects of the KH570 mass fraction on the microstructure and dielectric properties of TiO2-PTFE-PDMS composites were investigated, and the results showed that when the mass fraction was 5%, the composites exhibited better dielectric properties in the range of 2-12 GHz. Finally, an ultra-wideband antenna with an operating frequency band in the range of 2.37-11.66 GHz was prepared based on this composite substrate. The antenna demonstrated significant potential for future applications in detecting environmental thermal changes due to its special temperature-sensitive linear frequency shift characteristics, and its effect on the human body under bending conditions was studied. In addition, specific absorption rate (SAR) measurements were performed to assess the effects of antenna radiation on the human body in practical applications.

As microfluidic lab-on-a-chip technology advances, microfluidic microarrays, particularly those designed for cell sorting, have become increasingly vital in biomedical research. In inertial microfluidics, the use of a single helical channel has been a prevalent approach. However, this method often exhibits suboptimal separation efficiency, frequently falling below the 90% threshold. In this research, we introduce an innovative approach by integrating a conventional helical channel with a constriction-expansion channel design, creating a dual-layer helical structure. Furthermore, we introduced triangular micropillars into the microfluidic array, which successfully prevented the backflow of particles separated into the second layer from returning to the first layer, thereby further enhancing the stability and efficiency of the separation. The combination of this triangular micropillar configuration with the implementation of the double-layer helical structure significantly enhances the precision and purity of particle separation. Experimental results demonstrate exceptionally high separation efficiency. At a speed of 200 mu l min-1, the separation efficiency of the chip for particles is up to 99.1%, and the separation purity is up to 98.3%. This study presents a novel spiral channel design that facilitates microfluidic particle sorting. Leveraging the combined benefits of triangular micropillars and a dual-layer helical structure to achieve unprecedented performance in particle separation.

Characterizing electromagnetically induced transparency (EIT) effects using metasurfaces is a promising research work, but in the microwave field, most structures tend to be realized only in a single frequency band, which may limit their use. We innovatively propose a double-layer stacked structure to realize the EM-induced transparency effect with good incident angle insensitivity, which expands the practical applications. Secondly, we actively adjust the transmission window by adding and controlling the state of the PIN diode to realize the translation of the transmission window, which overcomes the defects of the conventional structure in a single frequency band. In addition, the slow-light effect produced by electromagnetic-induced transparent metasurfaces and the sensing characteristics when changing the dielectric constant of the object to be measured on the surface are further investigated. The near-field coupling mechanism of the structure is analyzed using the classical three-energy atomic model with the electromagnetic field variation system, and the physical mechanism of the electromagnetically induced transparent structure is explained in detail. Finally, the structure samples were processed and tested. The experimental results are in good agreement with the theoretical values. The design has potential applications in the fields of plasma switching, optical sensors and slow light device sensing.

This paper presents a waveguide Lens antenna at the W-band adopting dual-focusing Lens to improve the performance. The Lens antenna consisted of a waveguide slotted structure and lenses processed using NOA73 meet the demands of miniaturization for current communication systems. The antenna radome fabricated using NOA73 not only protects the antenna structure but also improves the gain of the antenna by about 9.5 dBi via electromagnetic wave dual-focusing. A prototype is fabricated using novel UV-LIGA technology. Measured results are compared with simulated values. Measured results confirmed the fabricated antenna operated in the W-band with a 10 dB fractional bandwidth (FBW) of 6.5% from 97.5 to 104 GHz and a peak gain of 22 dBi at 100 GHz in the direction perpendicular to the plane of the feed waveguide. A good agreement between simulation and measurement is obtained, demonstrating efficient radiations in the operating band.

This paper proposes a multi-band composite wearable antenna for wireless communication, which uses a monopole structure as the radiating body and achieves multi-band characteristics through slit-loading and multi-branching methods. A polymer composite substrate with high dielectric constant and low dielectric loss was prepared using in situ polymerization, and the optimal dielectric constant and loss angle tangent were obtained by controlling the coating ratio of melamine formaldehyde resin to carbon nanotubes (MWCNTs) and the filler doping rate to achieve miniaturization of the antenna. Comparative experimental results show that the obtained composites have high flexibility and good dielectric properties. The antenna operates in the frequency bands of 2.21-2.52 GHz, 3.07-3.87 GHz, and 4.36-6.03 GHz, which cover the frequency bands of WLAN and WiMAX and 5G applications. The antenna was fabricated and tested, and its performance roughly matched the simulation results. Meanwhile, the antenna has passed the SAR safety test and maintained a stable performance under different curvatures, so it has potential applications in the wireless communication system.

The iterative upgrading of the means of warfare has promoted the development of detection technology, and military activities are increasingly demanding target stealth. In this paper, a multifunctional metamaterial absorber is recommended, which simultaneously realizes the integrated stealth functions of ultra-wideband radar wave absorption, low infrared emission, and optically transparent. The structure is composed of an infrared shield, a radar-absorbing layer, and a reflective layer. Simulation results indicate that the absorption bandwidth in the radar band (1.81-20.4 GHz) is more than 90%, and the infrared emissivity is as low as 0.271 in the IR band (3-14 mu m). Moreover, it has the features of flexibility, angle stability (0-45 degrees), polarization insensitivity (0-90 degrees), and so on. Furthermore, the electric field current distribution and equivalent circuit model of the structure are analyzed, and a 180 mm*180 mm sample is built and tested; the results show that the simulated and actual measurements are in agreement, and it is expected that such absorbers will be used in areas such as aircraft.

A novel metamaterial is proposed and investigated to achieve bifunctional switching of water-based broadband absorption and polarization conversion. Given the dispersion properties of water in the microwave band, the structure exhibits more than 90 % absorption characteristics in the frequency of 12.2-24.45 GHz when the hybrid substrate is filled with water. Furthermore, the water-based structure maintains strong absorption up to 60 degrees incidence angle with wide angle and polarization independence properties. In addition, when the temperature rises from 0 to 100 degrees C, the water-based absorption maintains 90 % within the operating band. Then, when there is no water in the hybrid substrate, the structure switches to a polarization converter. The polarization conversion ratio (PCR) is up to 90 % in frequency of 12.4-16.5 GHz. Finally, the prototype is prepared to verify that its experimental results match the simulation. The versatile switchable metamaterial possesses essential applications in electromagnetic stealth and radiation protection due to the switching of absorption and polarization conversion capabilities, low cost, and ease of manufacture.