High-loss Materials Research Articles

An air gap correction method for permittivity extraction of high-loss materials

This paper developed a method for more accurate permittivity extraction of high-loss materials using the waveguide method to reduce the effect of the air gap. This method improves the Baker-Jarvis algorithm. It makes the errors of S-parameters caused by the air gap compensated by a correction factor β of the form: (S21 + S12) + β(S11 + S22). In our study, the correction results of β for materials on different frequencies and air gap sizes are quantitatively investigated. Furthermore, we propose a method to obtain an optimal frequency-independent β for different materials. A typical high-loss BeO-SiC ceramic commonly used in vacuum electron tubes is analyzed and discussed in detail. It shows that compared to traditionally utilizing only S21 (β = 0), adopting an optimal β can reduce the average errors of the complex permittivity from 17.7% to 7.9% with a 0.10 mm air gap. The proposed method is verified by measurements of unshaved and shaved samples.

Theoretical investigation of electromagnetic-thermal coupling of double-layer cylindrical concrete under microwave irradiation

Many experiments have been performed to study the heating properties of concrete under microwave irradiation. Microwave provides the non-uniform heating process, which cannot be reflected clearly through the experimental investigations. In this paper, a theoretical method is presented to investigate the electromagnetic-thermal coupling process of double-layer cylindrical concrete under microwave heating. The wave transmission and reflection were considered. An analytic solution is presented to predict transient heating process within a 3-dimensional double-layer concrete model induced by microwave heating. The inner aggregate is a microwave high loss material and the outer mortar was microwave low loss medium. Poynting theorem was employed to calculate the electric field distribution and microwave energy loss within concrete. Transient heat transfer process with an internal microwave heat source was investigated based on the classical heat transfer theory by employing integral transform technique. The results indicate that microwave heating effect depend on the concrete size, dielectric properties as well as microwave energy input. The temperature gradient was formed at the mortar-aggregate interface, which varied with the microwave heating parameters inputs. The analytical study will provide significant insight to promote the understanding of electric and temperature field in the two-layer composite concrete materials under microwave heating.

Quest for the porosity-regulated high dielectric and conductive performance of MOF by introducing nanoparticles: Performance evaluation at elevated temperatures

Metal-organic frameworks (MOFs) are among the novel materials that have drawn a lot of attention from the scientific and technological communities. There have been numerous reports of 3D MOFs in the scientific community, but due to distinct structural and electrical properties, scientists are particularly interested in zinc imidazole framework 8 (ZIF-8). Due to its characteristic low dielectric values, ZIF-8 is an excellent choice for low-dielectric applications. However, the incorporation of nanoparticles can increase the dielectric constant of ZIF-8. In this study, ZnO semiconducting nanoparticles are used as a filler of ZIF-8 due to their exceptionally high electron mobility, exciton binding energy, and wide band gap. We hypothesized that the incorporation of semiconducting nanoparticles (ZnO) inside ZIF-8 influences the porosity, pore size distributions, pore morphology, and interconnectivity of ZIF-8 which influences the polarization of pristine ZIF-8 and helps to increase the dielectric properties. ZnO has inherent ionic polarization which not only enhances the dielectric constant but also simultaneously decreases the dielectric loss which is essential for any dielectric materials. The dielectric constant was enhanced by 1.5 times after 5 wt% ZnO doping in ZIF-8 at room temperature and the enhancement was nearly five times at 150 °C. Simultaneously the dielectric loss decreases after ZnO doping compared to pristine ZIF-8. The tailoring of porosity, the number of pores, the presence of defects and oxygen vacancies are responsible for the modulated dielectric properties. The conductivity of ZIF-8 can also be tuned by the nanoparticles incorporation which indicates the larger production of drift electrons inside MOF in the presence of nanoparticles. The detailed morphological characteristics confirm the interaction between ZnO and ZIF-8. The result is a thorough understanding of the intrinsic and extrinsic electrical properties of ZIF-8 composites for future generations of technology. This work aimed to exploit possibilities of MOF towards high dielectric constant and low loss material by simple nanoparticle incorporation.

Enhanced terahertz high-harmonic generation from high-Q quasi-bound states in the continuum empowered by permittivity-broken metasurface

The extraordinary emergence of all-dielectric resonant meta-photonics underpinned by high refractive index and low optical loss materials promises a standout platform for unprecedented manipulation and subwavelength control of light. Recent significant breakthroughs in meta-photonics have to do with the exploration of the non-radiative eigenmodes that lie inside the light cone, called the bound states in the continuum (BICs), which have demonstrated considerable potential to achieve high quality (Q) factors but require ultra-small structure asymmetry, complicating fabrication and hindering precise control of Q factors. Here, we propose a scheme to excite quasi-BICs by breaking symmetry in the permittivity of the comprising meta-atoms where small permittivity perturbation renders the same effect in the conventional geometrically asymmetric design. Empowered by the insignificant permittivity perturbation introduced from chemical doping and carrier injection, arbitrarily small permittivity asymmetry, that is, infinitely high-Q factor, can be precisely and dynamically tailored. As an example of application, we numerically show the THz range, exceptionally high conversion efficiency for both third-harmonic and fifth-harmonic generation from the permittivity-broken metasurface (MS) benefiting from the extreme field confinement at high-Q quasi-BICs resonance. Our results present a feasible and efficient strategy to mitigate the shortcomings of previous photonic platform and shall shed light on the advances of nonlinear all-dielectric THz-MS.

Bamboo-shaped N-doped carbon nanotubes encapsulated with Co nanoparticles for improved microwave absorption properties

High reflection loss and wide absorption bandwidth materials are in great demand to prevent electromagnetic pollution and military applications. The composites prepared by combining different components with good dielectric and magnetic losses are expected to achieve ideal absorbing performance. In this study, a composite of cobalt nanoparticles enveloped in nitrogen-doped bamboo-like carbon nanotubes (Co@N-CNTs) was prepared by one-step annealing the mixture of melamine and cobalt nitrate at 800 °C in a mixed atmosphere of hydrogen and argon. Co nanoparticles derived from the reaction between H2 and cobalt nitrate during the sintering process were used as catalysts to prompt the carbonization of melamine and the formation of the bamboo-shaped N-doped carbon nanotubes, thus forming the composite structure of bamboo-shaped N-doped carbon nanotubes encapsulated with Co nanoparticles. This Co@N-CNTs composite not only had an excellent dielectric loss and magnetic loss but also greatly improved its impedance matching, thus having good electromagnetic wave absorption performance. The coating made from the Co@N-CNTs composite had a maximum reflection loss (RL) of −35.89 dB at only 1.8 mm thickness at 14.1 GHz and possessed an effective absorption bandwidth of up to 4.91 GHz (12.35–17.26 GHz), suggesting it a high-performance and wide-absorption bandwidth composite material.

Mid-infrared bimodal wide metamaterial absorber based on double-layer silicon nitride structure

Infrared band occupies a very important position in the electromagnetic wave band. Traditional infrared devices use the inherent properties of natural materials to achieve the regulation of electromagnetic waves, but the limited ability of such devices to regulate electromagnetic waves can't well meet our needs. In this paper, we reported a metamaterial absorber of Cr-Si3N4-Cr-Si3N4-Ti based on double-layer metal-insulator-metal (MIM). It is investigated with the optimal structural parameters of 490 nm, 330 nm, 30 nm, 720 nm, 120 nm, in descending order, at which the absorptive properties are studied. When the light wave is incident vertically, it can be obtained from the experimental simulation that this absorber has polarisation insensitivity. Because of the coupling effect of the surface plasmon resonance and the high-loss material, the bandwidth of absorption greater than 90% can reach 9190 nm, and the average absorption in the target long-wave infrared band (9.506∼18.145 μm) is 94.8%. By selecting different geometrical parameters of the structure, the absorption spectrum can be adjusted independently. In addition, the absorber has good incident angle insensitivity in TE and TM modes. Also, the absorber we proposed has a plain structure, is convenient for manufacturing, the material is easier to obtain, which ensures a good absorption bandwidth and average absorptivity, and the study of this metamaterial absorber has important applications in solar cells, satellite radiothermographs, photodetectors, and spectral imaging.

Direct Permittivity Reconstruction From Power Measurements Using a Machine Learning Aided Method

A machine learning aided (MLA) method is employed for the direct permittivity retrieval of dispersive and non-dispersive materials. The method requires low-cost measurements since it solely utilizes the amplitude of the transmission response ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$|S_{21}|$</tex-math> </inline-formula> ) to extract the complex permittivity. This precludes the need for a network analyzer, and therefore, the measurements can be performed using a power sensor. Unlike earlier works, however, the method introduced here does not require prior information about the dispersion model of the material under test (MUT), so it is applicable to a wider range of materials. The method is based on applying two artificial neural networks (ANNs) for the permittivity reconstruction of low and high-loss materials. The ANNs are trained using full-wave simulation results of a coaxial line loaded with different MUTs for the direct reconstruction of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon^\prime$</tex-math> </inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon^{\prime\prime}$</tex-math> </inline-formula> . As a proof of concept, several chemical liquids, their mixtures, and powdered samples were used to experimentally validate the technique within the 0.3–3 GHz band. The retrieved complex permittivities of samples were in good agreement with the reference data and those obtained by the well-known transmission/reflection Nicolson–Ross–Weir (NRW) method.

Reduced Graphene Oxide/Barium Ferrite Ceramic Nanocomposite Synergism for High EMI Wave Absorption.

The developed nanocomposite exhibits significantly enhanced shielding performance due to the synergistic effect of high dielectric and magnetic loss materials, which modifies the material's impedance and improves its absorption ability. Different weight percentages (0, 1, 5, 10, 15, 20, and 25 wt %) of thermally treated chemically reduced graphene oxide (TCRGO) were combined with two types of magnets, barium hexaferrite (BF) and magnetite (MAG), using a dry powder compaction technique to produce binary ceramic nanocomposite sheets. The shielding performance of a 1 mm thick compressed nanoceramic sheet over the X-band was evaluated using a vector network analyzer. The 25% TCRGO showed high shielding performance for both BF and MAG, while BF had a total shielding efficiency (SET) that exceeded MAG by 130%. The SET of 25 wt % TCRGO/BF was 52 dB, with a 41 dB absorption shielding efficiency (SEA). Additionally, the effect of different levels of incident electromagnetic wave power (0.001-1000 mW) at various thicknesses (1, 2, and 5 mm) was explored. At 1000 mW, the 5 mm TCRGO/BF had an SET of 99 dB, an SEA of 91 dB, and a reflection shielding efficiency (SER) of 8 dB. The use of BF as a hard magnet paired with TCRGO exhibited excellent and stable electromagnetic shielding performance.

A bilayer array metamaterial based on silicon carbon foam/FeSiAl for broadband electromagnetic absorption

In this paper, a bilayer array metamaterial (BAMM) based on silicon carbon (SiC) foam/FeSiAl composite was proposed and the electromagnetic (EM) absorption performance of the BAMM was enhanced by regulating the material composition and geometrical parameters. The introduction of magnetic FeSiAl particles contributed to the reinforced low-frequency absorption of the BAMM. The geometrical parameter design resulted in the broadened effective absorption bandwidth (EAB, reflection loss value≤−10 dB) by improving the impedance matching between the BAMM and the free space. At the same time, it was found that the tuning of the geometrical parameters has a more crucial effect on the absorption properties than the regulation of material composition. Moreover, the EM absorption mechanism was investigated by analyzing the distribution of the EM field and the power loss. In addition to the polarization and magnetic losses in the BAMM, the EM energy is mainly dissipated by the scattering effects concentrated at the outer edge of the unit cell and by the EM resonances between neighboring unit cells. The optimized SiC foam/FeSiAl-1based BAMM exhibits an effective absorption in the frequency range of 2–18 GHz by calculation, and then the corresponding experimental BAMM sample is prepared and measured. The experimental results are in good agreement with the simulations and demonstrate an EAB of 15.77 GHz, indicating that the geometrical parameters design based on high-loss materials is an attractive and efficient strategy to obtain broadband absorbers.

Monolayer Plasmonic Nanoframes as Large-Area, Broadband Metasurface Absorbers.

Broadband absorbers are useful ultraviolet protection, energy harvesting, sensing, and thermal imaging. The thinner these structures are, the more device-relevant they become. However, it is difficult to synthesize ultrathin absorbers in a scalable and straightforward manner. A general and straightforward synthetic strategy for preparing ultrathin, broadband metasurface absorbers that do not rely on cumbersome lithographic steps is reported. These materials are prepared through the surface-assembly of plasmonic octahedral nanoframes (NFs) into large-area ordered monolayers via drop-casting with subsequent air-drying at room temperature. This strategy is used to produce three types of ultrathin broadband absorbers with thicknesses of ≈200nm and different lattice symmetries (loose hexagonal, twisted hexagonal, dense hexagonal), all of which exhibit efficient light absorption (≈90%) across wavelengths ranging from 400-800nm. Their broadband absorption is attributed to the hollow morphologies of the NFs, the incorporation of a high-loss material (i.e., Pt), and the strong field enhancement resulting from surface assembly. The broadband absorption is found to be polarization-independent and maintained for a wide range of incidence angles (±45°). The ability to design and fabricate broadband metasurface absorbers using this high-throughput surface-based assembly strategy is a significant step toward the large-scale, rapid manufacturing of nanophotonic structures and devices.

Ultra-compact hybrid silicon:chalcogenide waveguide temperature sensor.

We demonstrate a real-time, reusable, and reversible integrated optical sensor for temperature monitoring within harsh environments. The sensor architecture combines the phase change property of chalcogenide glasses (ChG) with the high-density integration advantages of high index silicon waveguides. To demonstrate sensor feasibility, ChG composition Ge40S60, which is characterized by a sharp phase transition from amorphous to crystalline phase around 415 °C, is deposited over a 50 µm section of a single mode optical waveguide. The phase transition changes the behavior of Ge40S60 from a low loss to high loss material, thus significantly affecting the hybrid waveguide loss around the phase transition temperature. A transmission power drop of over 40dB in the crystalline phase compared to the amorphous phase is experimentally measured. Moreover, we recover the amorphous phase through the application of an electrical pulse, thus showing the reversible nature of our compact temperature sensor. Through integrating multiple compositions of ChG with well-defined phases transition temperatures over a silicon waveguide array, it is possible to determine, in real-time, the temperature evolution within a harsh environment, such as within a nuclear reactor cladding.

Strategy for Low‐Loss Optical Devices When Using High‐Loss Materials

Material loss, especially in metal and 2D materials, is the bottleneck for high‐performance integrated optical devices. Here, a novel concept by utilizing the high‐loss materials in a non‐Hermitian system instead of avoiding the loss materials. It is theoretically analyzed how the complex refractive index affects the loss of optical devices based on a two‐waveguide‐coupled non‐Hermitian system. The results reveal that the loss of optical devices can be improved by increasing the loss of materials or the difference in real refractive indexes. It is experimentally verified that a high loss material can be placed close to the optical waveguide without introducing non‐negligible loss to the optical devices, by demonstrating a thermo‐optic phase shifter with a metallic heater placed very close to the silicon waveguide. As a result, the insertion loss is only 0.1 dB for the 100 μm long heater with a gap of 400 nm, and the largest bandwidth for the metallic heater reaches up to 280 kHz. The finding offers a way to realize high‐performance optical devices with high‐loss materials, contributing to the practical applications of strongly absorbing materials based on non‐Hermitian optics.

The Design of a Low-Loss, Fast-Response, Metal Thermo-Optic Phase Shifter Based on Coupled-Mode Theory

A thermo-optic phase shifter is of great importance in silicon photonics. However, it is difficult to simultaneously achieve a good performance in insertion loss and in response speed by using traditional thermal tuning through a metallic heater. In this paper, based on coupled-mode theory, we propose a method to place high-loss materials close to the optical waveguide while maintaining the low loss of the optical device, which ensures the low insertion loss (~0.78 dB) of the phase shifter. Additionally, thanks to the very short distance between the rib waveguide and the chromium (Cr) heater, the phase shifter exhibits a high response speed (1.15 μs in rise time and 2.18 μs in decay time) with a measured bandwidth (BW) of 186 kHz. Moreover, we further optimize the structure of phase shifters, leading to the reduction of π-shift power consumption from 25.1 mW to 13.6 mW. Our proposed phase shifters have great potential in large-scale silicon photonic integrated circuits.

Optical Bound States in the Continuum Enabled by Magnetic Resonances Coupled to a Mirror.

Dielectric metasurfaces made of high refractive index and low optical loss materials have emerged as promising platforms to achieve high-quality factor modes enabling strong light-matter interaction. Bound states in the continuum have shown potential to demonstrate narrow spectral resonances but often require asymmetric geometry and typically feature strong polarization dependence, complicating fabrication and limiting practical applications. We introduce a novel approach for designing high-quality bound states in the continuum using magnetic dipole resonances coupled to a mirror. The resulting metasurface has simple geometric parameters requiring no broken symmetry. To demonstrate the unique features of our photonic platform we show a record-breaking third harmonic generation efficiency from the metasurface benefiting from the strongly enhanced electric field at high-quality resonances. Our approach mitigates the shortcomings of previous platforms with simple geometry enabling facile and large-area fabrication of metasurfaces paving the way for applications in optical sensing, detection, quantum photonics, and nonlinear devices.

Simple, Fast, and Accurate Broadband Complex Permittivity Characterization Algorithm: Methodology and Experimental Validation from 140 GHz up to 220 GHz

Accurate permittivity characterization has attracted a lot of attention in various areas. Resonant characterization methods are well-known for their accuracy, but they are restricted in very narrow frequency ranges, and thus, they are normally not recommended to be used for dispersive or high-loss materials. Transmission line characterization techniques are outstanding for being inexpensive, accurate, and broadband, but the algorithms are often complex to perform. This paper proposes a fast, simple, and accurate broadband permittivity characterization algorithm, which is mainly suitable for millimeter-wave applications. It combines a general line–line method and a closed-form algorithm, extracting the complex permittivity of the material under test (MUT) without the need for calculating any intermediate parameters. Validation measurements on de-ionized water in the frequency range from 140 to 220 GHz are in very good agreement with the literature data, which successfully indicates that the proposed algorithm is reliable and accurate for millimeter wave permittivity characterization.

Dielectric loss and electromagnetic absorption performance study of 1T/2H-MoS2/Mo2S3 nanocomposites with different ratios

High dielectric loss materials have an important application in electromagnetic (EM) absorption fields. In this paper, the ternary nanocomposites: 1T/2H-MoS2/Mo2S3 with heterogeneous interfaces are synthesized by hydrothermal method. XRD, XPS, FTIR, SEM, and TEM measurements are applied to study the structure, morphology, and composition. The frequency spectra of complex permittivity (εr-f) are measured in 2–18 GHz by vector network analyzer. The results show that the nanocomposites have higher dielectric loss angle tangents than the reported 2H-MoS2 absorbers. Based on the εr-f spectra, the reflection loss-frequency curves (RL−f) are simulated at given thicknesses. An effective absorption bandwidth of 5.2 GHz (12.8–18 GHz) and a RL peak of −29.49 dB are achieved in a thin thickness of 1.62 mm, which are comparable to the reported 2H-MoS2 absorbers with complex composition, showing that the 1T/2H-MoS2/Mo2S3 nanocomposites have great application potential as an EM wave absorber in the Ku band.

Modified Waveguide-Based Method for Microwave Characterization of High-Loss Materials

A waveguide-based measurement configuration is proposed, as a modification to the traditional completely filled waveguide technique, for microwave characterization of relatively thin and high-loss materials. This method is aimed to overcome the large measurement errors caused by gaps and cross-sectional distortions, which are of great concern when measuring high-loss samples, such as unidirectional (UD) carbon-fiber reinforced polymer (CFRP) composite sheets. In this article, the influences of critical parameters, namely, dielectric constant, loss factor, material thickness, and waveguide misalignment, on measured complex permittivity of several diverse samples, are fully investigated through numerical electromagnetic simulations and measurements at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula> -band (8.2–12.4 GHz). By the virtue of the electromagnetic properties associated with high-loss dielectric materials, it is found that this technique coupled with the Nicolson–Ross–Weir (NRW)/Backer–Jarvis conversion procedure is a capable method for measuring high-loss dielectric materials.

Inversion of P-Band Electromagnetic Parameters Based on a Genetic Algorithm and Method of Moments

Considering the difficulty in measuring the P-band electromagnetic parameters of porous materials such as graphene foam (GF), this paper proposes a free-space frequency-domain technology to measure the electrical properties of finite-plate materials from multiple perspectives. First, the multiangle reflectance of the sample was measured with the arch method; second, an electromagnetic simulation model consistent with the sample size was established, and the reflectance of different angles was calculated using the method of moments (MoM). Finally, the genetic algorithm (GA) was optimized for the electromagnetic parameters such that the reflective difference between the electromagnetic simulation model and the test obtained was minimized. The validity of the method was verified by reconstructing the electromagnetic parameters of a 1 m×1 m×0.03 m absorbing material at 0.5 GHz. The unique advantage of this method is that it solves the problem of inversion of electromagnetic parameters based on the multiangle reflectivity of an absorbing material plate within three times the wavelength. Because the electromagnetic simulation model can automatically divide the appropriate mesh size according to the size of the electromagnetic parameters, this method is suitable for high-loss and low-loss materials. In addition, this method avoids the special processing requirements regarding the shape size of the absorbing material, which has a wide application scope and low cost.

An end-fire low profile patch antenna to work on WiMAX frequencies used for harvesting power supply

In this paper, an end-fire microstrip patch antenna (MPA) is proposed of 3 GHz as a center frequency, designed, simulated, and measured to work on WiMAX frequencies within standard of 802.16e (WiMAX). A high gain ranged between (12.117-13.324) dB, high front to back ratio (F/B) of (35.770) at the center frequency, a wide band of 1.701 GHz, low profile, and semi-ideal voltage standing wave ratio (VSWR) of 1.053 is achieved. The simulation is done using computer simulation technology (CST-MW). The proposed design is based on two Fire-retardant substrates (FR-4) of relative permittivity (ε) 4.3+j0.025 and 1.53 mm thickness for each one, which is considered a high loss material. The measurement results show good agreement with the simulated results. In addition, the design can be used for harvesting power supply from mobile towers. Finally, the proposed design is compared with two other designs in terms of power conversion efficiency and overall size.

“Viscotaxis”- directed migration of mesenchymal stem cells in response to loss modulus gradient

Directed cell migration plays a crucial role in physiological and pathological conditions. One important mechanical cue, known to influence cell migration, is the gradient of substrate elastic modulus (E). However, the cellular microenvironment is viscoelastic and hence the elastic property alone is not sufficient to define its material characteristics. To bridge this gap, in this study, we investigated the influence of the gradient of viscous property of the substrate, as defined by loss modulus (G″) on cell migration. We cultured human mesenchymal stem cells (hMSCs) on a collagen-coated polyacrylamide gel with constant storage modulus (G′) but with a gradient in the loss modulus (G″). We found hMSCs to migrate from high to low loss modulus. We have termed this form of directional cellular migration as “Viscotaxis”. We hypothesize that the high loss modulus regime deforms more due to creep in the long timescale when subjected to cellular traction. Such differential deformation drives the observed Viscotaxis. To verify our hypothesis, we disrupted the actomyosin contractility with myosin inhibitor blebbistatin and ROCK inhibitor Y27632, and found the directional migration to disappear. Further, such time-dependent creep of the high loss material should lead to lower traction, shorter lifetime of the focal adhesions, and dynamic cell morphology, which was indeed found to be the case. Together, findings in this paper highlight the importance of considering the viscous modulus while preparing stiffness-based substrates for the field of tissue engineering. Statement of significanceWhile the effect of substrate elastic modulus has been investigated extensively in the context of cell biology, the role of substrate viscoelasticity is poorly understood. This omission is surprising as our body is not elastic, but viscoelastic. Hence, the role of viscoelasticity needs to be investigated at depth in various cellular contexts. One such important context is cell migration. Cell migration is important in morphogenesis, immune response, wound healing, and cancer, to name a few. While it is known that cells migrate when presented with a substrate with a rigidity gradient, cellular behavior in response to viscoelastic gradient has never been investigated. The findings of this paper not only reveal a completely novel cellular taxis or directed migration, it also improves our understanding of cell mechanics significantly.