Near-field Technology Research Articles

Experimental study on the characteristics of near‐field distribution of chips based on nano‐diamond quantum magnetometer

Microwave field near-field radiation imaging technology is widely used in the failure analysis of chips, but due to the low resolution, it is hard to obtain the field distributions of miniaturized and precision devices. In this article, we built two testing systems based on the method of electromagnetic induction and diamond color-center, respectively. The traditional system uses a multilayer PCB microstrip, while the novel system uses nanoscale high-sensitivity sensing of color centers in the design of resonant microwave field probes with near-field measurement sensitivity to enable nanoscale high-sensitivity measurements of different physical quantities. We tested two devices in this article, and the results show that compared with traditional measurement method, the novel method promotes higher resolution (submicron level), higher sensitivity, and nondestructive imaging. This method can accurately characterize the near-field distribution of microwave integrated circuit chips, such as spiral antennas, and amplifiers. Especially in the amplifier chip, the signal change trend of the amplifier circuit can be clearly characterized. It is expected to provide a new measurement concept in real word applications, such as chip electromagnetic compatibility, microwave chip failure analysis, and antenna near-field scanning radiation emission testing.

Developing a multimodal biosensor for remote physiological monitoring

IntroductionSeveral UK military expeditions have successfully used physiological sensors to monitor participant’s physiological responses to challenging environmental conditions. This article describes the development and trial of a multimodal wearable biosensor...

Accurate Far-Field Measurement of Wide-Angle Scanning Phased Array Antennas

This paper presents a new approach to the accurate determination of the far-field (FF) pattern of wide-angle scanning phased array antennas (PAAs) that uses planar near-field (NF) technology. When PAAs are engaged in wide-angle scanning, a finite scanning plane and inaccurate probe compensation can lead to truncation errors. The proposed approach reduces these by rotating the PAA to make its main beam perpendicular to the scanning plane. To verify the effectiveness of the approach, both theoretical calculations and actual measurements were undertaken. The simulated and measured results prove that the proposed method is more accurate than traditional NF technology for a large PAA scanning angle, such as ψ0=50° and Δ0=50° (in simulation; 54° when measured).

이식형 골전도 보청기 무선 데이터 전송을 위한 근거리 자기 유도 기술의 무선 링크 최적화에 대한 연구

이식형 골전도 보청기 무선 데이터 전송을 위한 근거리 자기 유도 기술의 무선 링크 최적화에 대한 연구

Developments and Recent Progresses in Microwave Impedance Microscope

Microwave impedance microscope (MIM) is a near-field microwave technology which has low emission energy and can detect samples without any damages. It has numerous advantages, which can appreciably suppress the common-mode signal as the sensing probe separates from the excitation electrode, and it is an effective device to represent electrical properties with high spatial resolution. This article reviews the major theories of MIM in detail which involve basic principles and instrument configuration. Besides, this paper summarizes the improvement of MIM properties, and its cutting-edge applications in quantitative measurements of nanoscale permittivity and conductivity, capacitance variation, and electronic inhomogeneity. The relevant implementations in recent literature and prospects of MIM based on the current requirements are discussed. Limitations and advantages of MIM are also highlighted and surveyed to raise awareness for more research into the existing near-field microwave microscopy. This review on the ongoing progress and future perspectives of MIM technology aims to provide a reference for the electronic and microwave measurement community.

Developments and Recent Progresses in Microwave Impedance Microscope

Microwave impedance microscope (MIM) is a near-field microwave technology which has low emission energy and can detect samples without any damages. It has numerous advantages, which can significantly suppress the common-mode signal as the sensing probe separates from the excitation electrode, and it is a powerful tool to characterize electrical properties with high spatial resolution. This article reviews the major theories of MIM in detail which involve basic principles and instrument configuration. Besides, this paper summarizes the improvement of MIM properties, and its cutting-edge applications in quantitative measurements of nanoscale permittivity and conductivity, capacitance variation and electronic inhomogeneity. The relevant implementations in recent literature and prospects of MIM based on the current requirements are discussed. Limitations and advantages of MIM are also highlighted and surveyed to raise awareness for more research into the existing near-field microwave microscopy. This review on the ongoing progress and future perspectives of MIM technology aims to provide reference for the electronic and microwave measurement community.

Tight focus and field enhancement of terahertz waves using a probe based on spoof surface plasmons

In order to improve the resolution of terahertz near-field microscopic imaging technology, an ultra-thin thickness-graded silver-plated strip probe with the same duty cycle is designed to realize the excitation of spoof surface plasmons. By comparing with two other probes with different structures, it can be found that the thickness-graded silver-plated strip probe can produce a strong electric field enhancement effect. Thereafter, the influence of the polarization direction of the incident electric field and the number of periodic metal stripes on the electric field which are generated at the tip of the probe is investigated. It is found that this case is highly consistent with the electric field distribution in Richards-Wolf vector diffraction theory when the incident light is linearly polarized. The electric field intensity generated at the tip of the thickness-graded silver-plated strip probe can be flexibly and effectively manipulated by changing the polarization direction of the incident electric field. When the number of thickness-graded silver-plated strips is 12, the minimum size of the focal spot is 20 μm, which is λ/150. When the number of thickness-graded silver-plated strips is 4, the electric field intensity enhancement factor at the focal spot is 849. The electric field intensity enhancement factor at the focal spot increases continuously as the number of periodic metal stripes increases, and the size of focal spot decreases continuously as the number of periodic metal stripes decreases. This result shows that the tight focusing and electric field enhancement of terahertz waves can be achieved by using an ultra-thin thickness-graded silver-plated strip probe. The research results in this paper have important guiding significance for manipulating the electric field in the terahertz band.

Development of MMG sensors using PVDF piezoelectric electrospinning for lower limb rehabilitation exoskeleton

In this study, a new type of fiber-based mechanomyography (MMG) sensor was developed and used as a motion on/off trigger sensor for a lower limb rehabilitation exoskeleton (LLRE). Piezoelectric material, polyvinylidene difluoride (PVDF), was applied to fabricate a MMG sensor, using the near-field electrospinning technology to electrically spin PVDF fibers to ∼5-10 μm in diameter. PVDF fibers attached on an interdigitated (IDT) electrode with different pole pairs and interspaces were packaged into a MMG sensor. This MMG sensor was stuck on the thigh muscles to detect and acquire human motion intention signal, then trigger the controller and actuate the LLRE. The LLRE multi-axis control system included a master and four slave controllers. The master controller released the command signal to control the slave controllers via controller area network (CAN). A multi-axis control system was developed to actuate the joints of hips and knees of both legs by the LLRE. In the study, commercial electromyography (EMG) sensors were also to compare with the as-made MMG sensors. Results showed that the maximum signal amplitude of the commercail EMG sensor was about ∼0.2 V, whereas the MMG sensor was about ∼2.8 V. The signal-to-noise ratio (SNR) of EMG was about ∼4, while that of MMG was about ∼25. From physiological signals captured from the MMG sensor for the human walking with the LLRE, this new sensor improved the sensitivity in driving the LLRE.

High Depth-of-Field Nanostructures by Rotational Near-Field Photolithography

Rotational near-field photolithography uses one or an array of plasmonic lenses to directly pattern features on a rotating substrate that is coated with a very sensitive photoresist. Critical for this method is its limited etching depth. We investigate and demonstrate that the depth-of-field of the so-obtained nanopatterns is determined by both the refractive index and the thickness of the air/photoresist multi-dielectric layer. Using the transfer-matrix theory, the bounded air/photoresist dielectric layer refracts the light at the interface, which causes the constructive interference of surface plasmon polaritons (SPPs) to be confined. The wavelength of the SPPs decreases with increasing photoresist thickness. Both the simulation and experiment indicate that high depth-of-field nanostructures can be obtained by optimizing the resonance wavelength of SPPs due to the response of the system. Combining this with high-speed rotational near-field photolithography technology, we find that nanostructures with four times the depth-of-field compared with the previous off-resonance system can be obtained using organic photoresists with this optimization.

Pushing the limits of deep-ultraviolet scanning near-field optical microscopy

Deep-ultraviolet (DUV) microscopy and microspectroscopy have received much attention in label-free live-cell imaging, selective molecular analysis, and optical characterizations of ultrawide bandgap materials. Far-field optics approaches usually suffer from the diffraction limit of light. Meanwhile, near-field optics technology is immature in the DUV spectral region. Herein, we develop a DUV scanning near-field optical microscope (SNOM) with an excitation wavelength of 210 nm. The fourth harmonic generation of a continuous-wave Ti:sapphire laser is the excitation source. Two negative feedback control systems stabilize the power and pointing, allowing scanning microscopy to be carried out over a long period of time even in the DUV spectral region. A reflective objective couples the excitation beam onto an optical fiber probe. The optical fiber probe is solarization-resistant and is not coated by metallic materials. The reflective-based objective optical design does not introduce chromatic aberrations in the detection signals. Our DUV-SNOM is used to measure the photoluminescence (PL) spectra of the quantum well structure of aluminum gallium nitride, which is an ultrawide bandgap material. The PL mapping images indicate that emissive localization centers can be individually visualized via our DUV-SNOM with a lateral resolution exceeding 150 nm.

Development of concept of near-field technology in designing effective small-aperture microwave antennas

Development of concept of near-field technology in designing effective small-aperture microwave antennas

Comparative study on the paraxial approximation errors of tightly focused fundamental Gaussian beams

When the beam waist size is on the order of or smaller than a wavelength, the traditional Gaussian solution exhibits noticeable errors in describing a tightly focused laser beam of the fundamental mode. The spatial distributions of the paraxial approximate errors of the Gaussian solution to the paraxial Helmholtz equation, as compared with Sapozhnikov’s exact solution to the scalar Helmholtz equation, are illustrated, tabulated, and discussed systematically. The maximum and average errors of the Gaussian solution are presented for a list of different specified waist sizes of laser beams. We found that the maximum error distribution is of an annular structure and contains the largest error ring on the waist plane. The laser beam waist should be >1.2 wavelengths for a 1% error, while the beam waist should be >3.5 wavelengths for a 0.1% error. This study provides a useful criterion to ascertain whether the traditional Gaussian solution or the exact solution is to be used to describe the fundamental laser beam in optical engineering. The results exhibit potential applications in micronano technology, near-field optical technology, and other fields where tightly focused laser beams are utilized.

Particle Velocity Sensor and Its Application in Near-Field Noise Scanning Measurement

The Particle Velocity Sensor (PVS) is a kind of acoustic transducer which measures the particle velocity directly with figure-of-eight directivity. This paper proposes a near-field noise scanning technology based on the research of PVS, pressure-particle velocity (P-U) probe, and its application in noise source identification. Firstly, the principle and characteristics of PVS are presented. Secondly, a P-U probe is designed on the basis of PVS development. Finally, the noise measurement experiment for a single source is arranged and conducted. The result shows that the proposed P-U probe performs well in near-field noise source identification and localization.

Effect of added resonators in RFID system at 13.56 MHz

In this study, a reader antenna including resonators is proposed to improve detection of a small moving tag in the case of tracking a radiofrequency identification (RFID) system. The near-field RFID technology is based on load modulation, the input impedance on the reader coil and the mutual inductance between the reader and tag coils are the main parameters for performing detection. They are calculated from the impedance matrix parameters. The added resonators change all the parameters of the impedance matrix consequently the input impedance and mutual inductance are also changed. In this study, analytical formulation defining the equivalent impedance matrix parameters is developed. These formulae are used to evaluate the performance of the proposed design according to the tag misalignment (lateral and angular). From the calculation and simulation results, a frequency shift in the equivalent input impedance is found. To avoid this problem, optimising the positioning of the resonators on the reader coil is performed. This study is confirmed by measures of RFID detection for a reader prototype (with and without resonators) and a small commercial tag. Both the surface and volume of detection of the small moving tag (lateral and angular misalignment) are improved by the principle of added resonators.

Notice of Retraction: Analysis of Near-Field Shielding Effectiveness for the SiP Module

In this letter, near-field scanning technology is utilized to analyze the shielding effectiveness (SE) of the system-in-package (SiP) module at the frequency of 1–6 GHz. Different definitions of the near-field SE are explored and analyzed. The SE is defined by using values of the radiated magnetic near-field from the SiP module, including the maximum value, the spatial averaged value, and the value at the same observation point, respectively. The SE defined by the spatial averaged value is a reasonable method to represent the overall SE of a well-shielded SiP module especially at low frequencies. Besides, a comparison of the SE between the reverberation chamber measurement and averaged magnetic near field is carried on. Good consistency is obtained, which confirms the reliability and efficiency of the near-field scanning method.

Numerical modeling and analysis of plasmonic flying head for rotary near-field lithography technology

Rotary near-field lithography (RNFL) technology provides a route to overcome the diffraction limit with a high throughput and low cost for nanomanufacturing. Utilizing the advantage of the passive flying of a plasmonic head, RNFL can achieve a 10 m/s processing speed with a perfect near-field condition at dozens of nanometers. The flying performance of the plasmonic flying head (PFH) is the pivotal issue in the system. The linewidth has a strong correlation with the near-field gap, and the manufacturing uniformity is directly influenced by the dynamic performance. A more serious issue is that the unexpected contact between the PFH and substrate will result in system failure. Therefore, it is important to model and analyze the flying process of the PFH at the system level. In this study, a novel full-coupled suspension-PFH-air-substrate (SPAS) model that integrates a six-degree of freedom suspension-PFH dynamics, PFH-air-substrate air bearing lubrication, and substrate vibration, is established. The pressure distribution of the air bearing is governed by the molecular gas lubrication equation that is solved by the finite element method (FEM) with a local pressure gradient based adaptive mesh refinement algorithm using the COMSOL Multiphysics software. Based on this model, three designs of the air bearing surface are chosen to study the static, dynamic, and load/unload performance to verify whether it satisfies the design requirements of RNFL. Finally, a PFH analysis solver SKLY.app is developed based on the proposed model.

A novel squeeze-film air bearing with flexure pivot-tilting pads: Numerical analysis and measurement

This study proposes a novel squeeze-film air bearing based on near-field acoustic levitation technology. Unlike previous squeeze-film bearings, the new bearing employs flexure pivot-tilting pads as vibration surfaces and provides higher vibration amplitude and better stability for rotor systems. The flexure pad structure eases processing and adapts well to squeeze action. This paper presents a theoretical model of the new bearing that combines models for squeeze film and flexure pivot-tilting pads to study the float characteristics. Resonant frequency and vibration mode of the bearing were obtained by using finite element modelling and validated by experimental results. The authors investigated the mechanism of pressure generation of squeeze film and pad movement. The load carrying capacity of the bearing was experimentally investigated. Numerical and experimental results show that the proposed bearing is a feasible non-contact bearing for high-speed and high-precision rotating machineries.

High-speed near-field photolithography at 16.85 nm linewidth with linearly polarized illumination.

Plasmonic focusing was investigated in concentric rings with a central pillar under linearly polarized illumination with a specific incident angle. When changing the incident angle of linearly polarized beam between 6 and 15 degree away from the normal direction, the focal spot size can keep a steady value of 37 nm, smaller than the focal spot with the radially polarized beam at the same excited condition, 45 nm. Combining this with the high-speed near-field photolithography technology, we demonstrated a plasmonic lithography with 16.85 nm linewidth on both organic and inorganic photo-resists in large scale at scanning speeds up to 11.3 m/s. This inclined linearly polarized illumination is easy to realize in a prototype of near-field photolithography system, and it opens a new cost effective approach towards the next generation lithography for nano-manufacturing.

Chip-Based Near-Field Terahertz Microscopy

Near-field terahertz (THz) imaging is vital to investigations in subwavelength regions down to the micro/nanometer scale. This technology is particularly useful for examining objects, such as nanomaterials, polymers, cells, and biomolecules. The first part of this paper briefly explains two types of near-field THz imaging technologies: aperture type and apertureless type. The second part explains our chip-based near-field imaging technology. We perform collection-mode near-field THz imaging by scanning an evanescently coupled THz detector closely across a sample surface. The implementation of a magnetically tunable THz detection method further enables us to obtain frequency-selective near-field THz images. As an application of this technology, cryogenic THz-emission imaging is presented, wherein THz radiation associated with electron injection into a semiconductor device is imaged with no THz pump source. This technique provides direct information about the spatial distribution of electrons injected from an electrode into a semiconductor channel.

(Invited) Near-Field Coupling Integration Technology

Invention of IC was driven by “Tyranny of Numbers”, a challenge implied by large number of interconnects in a large-scale system. Modern ICs integrate many miles of wiring and billions of contacts. Moore's Law, however, will die, and we cannot rely just on integration on a chip. A revolutionary solution of the connection problem is now needed for further integration. Our proposal, as More-Than-Moore, is to replace mechanical connection using wiring, solder, and connectors by electrical one using near-field coupling. Transmission Line Coupler by electromagnetic coupling for module connection and ThruChip Interface by inductive coupling for chip stacking is presented and discussed in this paper.