Suspended Platform Research Articles

Design and Simulation of High-Temperature Micro-Hotplate for Synthesis of Graphene Using uCVD Method.

The uCVD (microchemical vapor deposition) graphene growth system is an improved CVD system that is suitable for scientific research and experimental needs, and it is characterized by its rapid, convenient, compact, and low-cost features. The micro-hotplate based on an SOI wafer is the core component of this system. To meet the requirements of the uCVD system for the micro-hotplate, we propose a suspended multi-cantilever heating platform composed of a heating chip, cantilevers, and bracket. In this article, using heat transfer theory and thermoelectric simulation, we demonstrate that the silicon resistivity, current input cross-sectional size, and the convective heat transfer coefficient have a huge impact on the performance of the micro-heating platform. Therefore, in the proposed solution, we adopt a selective doping process to achieve a differentiated configuration of silicon resistivity in the cantilevers and heating chip, ensuring that the heating chip meets the requirements for graphene synthesis while allowing the cantilevers to withstand high currents without damage. Additionally, by adding brackets, the surfaces of the micro-hotplate have the same convective heat transfer environment, reducing the surface temperature difference, and improving the cooling rate. The simulation results indicate that the temperature on the micro-hotplate surface can reach 1050.8 °C, and the maximum temperature difference at different points on the surface is less than 2 °C, which effectively meets the requirements for the CVD growth of graphene using Cu as the catalyst.

Integrated suspended lipid membrane platform: Harnessing amperometric and single-molecule capabilities for deep insights into fusion dynamics

Integrated suspended lipid membrane platform: Harnessing amperometric and single-molecule capabilities for deep insights into fusion dynamics

Topology optimization for piezoresistive nanomechanical surface stress sensors in anisotropic 〈111〉 orientations

Microelectromechanical systems (MEMS)-based piezoresistive nanomechanical sensors are compact sensing platforms widely employed in vapor sensing, environmental monitoring, and biosensing. Despite their extensive utility, their lower sensitivity relative to their optical readout counterparts has been a limiting factor, constraining the wider application of this technology. Prior research has suggested that alternative silicon orientations, such as 〈111〉 orientations in (110) wafers, can significantly improve the sensitivity of piezoresistive sensors. However, the complexity of optimizing two-dimensional stress distribution and handling anisotropic elasticity has made device design a formidable task, leaving this promising avenue largely unexplored. To address this challenge, we employ density-based topology optimization to generate a series of optimized designs for piezoresistive nanomechanical sensors manufactured along 〈111〉 orientations. The properties of the immobilization layer—the functional coating on the sensor—are parametrically varied to explore optimal designs. Our study reveals a transition in optimized designs from a double-cantilever configuration to a suspended platform configuration, dictated by the stiffness ratio between the immobilization layer and the silicon layer. This transition is attributed to the shift in the neutral plane and the prevailing stress relaxation mechanism. In addition, we scrutinize the effects of piezoresistor geometry and find that the optimized designs depend asymmetrically on the piezoresistor position, a characteristic stemming from the anisotropic elasticity in 〈111〉 orientations. These optimized designs, verified by finite element analysis (FEA), demonstrate a notable improvement in sensitivity of more than 20% when benchmarked against traditional rectangular designs and equivalent optimized designs in conventional orientations, thereby validating the effectiveness of the present model. This study provides crucial knowledge for the design of piezoresistive biosensors, facilitating more efficient geometric design in future sensor development.

High-speed mid-infrared graphene electro-optical modulator based on suspended germanium slot waveguides.

The mid-infrared (MIR) region is attracting increasing interest for on-chip synchronous detection and free-space optical (FSO) communications. For such applications, a high-performance electro-optical modulator is a crucial component. In this regard, we propose and investigate a graphene-based electro-absorption modulator (EAM) and microring modulator (MRM) using the suspended germanium waveguide platform. The modulators are designed for the second atmospheric window (8 to 12 µm). The incorporation of double-layer graphene on the suspended slot waveguide structure allows for the significant enhancement of light-graphene interaction, theoretically achieving a 3-dB bandwidth as high as 78 GHz. The EAM shows a calculated modulation depth of 0.022-0.045 dB/µm for the whole operation wavelength range. The MRM exhibits a calculated extinction ratio as high as 68.9 dB and a modulation efficiency of 0.59 V·cm around 9 µm. These modulators hold promise for constructing high-speed FSO communication and on-chip spectroscopic detection systems in the MIR atmospheric window.

Quantifying and mitigating optical surface loss in suspended GaAs photonic integrated circuits.

Understanding and mitigating optical loss is critical to the development of high-performance photonic integrated circuits (PICs). In particular, in high refractive index contrast compound semiconductor (III-V) PICs, surface absorption and scattering can be a significant loss mechanism, and needs to be suppressed. Here, we quantify the optical propagation loss due to surface state absorption in a suspended GaAs PIC platform, probe its origins using x-ray photoemission spectroscopy and spectroscopic ellipsometry, and show that it can be mitigated by surface passivation using alumina (Al2O3).

АВТОНОМНЫЙ РОБОТ ДЛЯ МОНИТОРИНГА НАЗЕМНЫХ АРХЕОЛОГИЧЕСКИХ РАСКОПОК

The great interest in cultural heritage reflects a person's desire to know and understandtheir origins and achievements. However, archaeological sites, like the natural environment, arefinite non-renewable resources. Of all the types of heritage under threat, archaeological sites andtheir wealth of information and artifacts are the most threatened. In current practice, options forthe preservation of archaeological sites include reconstruction, reassembly (anastilesis), in situ conservation and protection, including shelter and/or tissue consolidation, ex situ preservation byrelocation, and reburial with or without site interpretation. her. However, it is very important notto move or lose artifacts during archaeological excavations. If they are lost or moved, their informationpotential is lost. In order to ensure constant control of the process of archaeological research,fixing the artifacts found, building a three-dimensional model of the object under studyand ensuring safety at the site, an excavation monitoring system has been developed, deployed onan autonomous robot. The objective of this study is the development of hardware and software forthe robot. The robot is a suspended platform for data collection, the movement of which is providedby several cables fixed on fixed supports. The movement of the platform (both in the plane andin height) is provided by changing the length of the cables. Such a movement scheme makes itpossible to move the platform in the entire plane of the triangle formed by the fixed supports, aswell as to descend or ascend to a height limited by the height of the supports themselves. The dataacquisition platform is a flat platform with a communication module, a microcontroller and abattery installed on it. A gyro stabilizer is attached to the bottom, with a video camera and arangefinder mounted on it, which allows you to dampen vibrations during the movement of theplatform and external disturbances. A multi-agent algorithm for the operation of the robot monitoringsystem during excavation is presented. A program has been developed for managing andcollecting data from the monitoring system of archaeological sites.To test the monitoring system, arobot prototype was made, which was tested during excavations of a complex of archaeologicalmonuments in the Baksan region of the Kabardino-Balkarian Republic.

A compact low‐pass filter using a miniaturized capacitor and honeycomb cavity on substrate integrated suspended line platform

AbstractThis article proposes a compact low‐pass filter (LPF) using a miniaturized capacitor, and honeycomb cavity based on the substrate integrated suspended line platform. A new method for miniaturizing capacitors is proposed, and simultaneously honeycomb cavities are adopted to extend the stopband. As a design case, a seven‐order quasi‐lumped‐element LPF with a cutoff frequency of 0.6 GHz is designed, fabricated, and tested. The size of the LPF is 0.085λg × 0.015λg × 0.012λg, and a wide stopband from 0.82 to 67 GHz with a suppression level greater than 20 dB is obtained.

MEMS enabled suspended silicon waveguide platform for long-wave infrared modulation applications

Long-wave infrared (LWIR, 6–14 µm) is an important wavelength range as it covers abundant vibrational molecular fingerprints that can be used for gas/liquid sensing and absorption spectroscopy. Silicon waveguide-based passive photonic devices that offer advantages toward chip-scale miniaturization of photonic integrated circuits (PIC) and photonic sensors in LWIR have been explored. However, the modulation of Si-based guided-wave propagation in LWIR remains less reported. Here, we demonstrate a MEMS tunable directional coupler operating at a long-wave infrared wavelength range (6.4–7 µm) using suspended Si waveguides with subwavelength gratings. Leveraging the membrane transfer technology, the whole photonic waveguide device membrane is transferred onto a receiver substrate with a cavity that allows sufficient displacement for MEMS electrostatic actuation. The proposed device experimentally achieved an optical attenuation of −14.25 dB with 90 V DC bias voltage, while having a response time of 177 µs. In addition, the demonstration of using such a device for computational spectroscopy has been validated.

An active‐passive cascaded bandpass filter with an 88 kHz–1.1 GHz bandwidth on substrate‐integrated suspended line platform

AbstractThis letter proposes an active‐passive cascaded bandpass filter based on the substrate‐integrated suspended line platform for the first time. By cascading an active‐RC highpass circuit with a passive‐LC lowpass filter circuit, the proposed filter achieves a GHz bandwidth, an extremely low cut‐off frequency, and a controllable in‐band gain. It has the advantages of compact size, DC‐offset cancellation, and self‐packaging. As proof of concept, a sixth‐order bandpass filter was designed and fabricated. The measured 3‐dB bandwidth is from 88 kHz to 1.1 GHz with a 5.8 dB in‐band gain, and the circuit area is only 0.021 × 0.022 λg, where λg is the guided wavelength at 0.55 GHz.

A SOI Out-of-Plane Electrostatic MEMS Actuator Based on In-Plane Motion

This work describes a novel micromechanical structure capable of producing out-of-plane motion from in-plane forces generated by electrostatic microelectromechanical system (MEMS) actuators. The MEMS actuator is fabricated in a commercial silicon-on-insulator (SOI) MEMS process and is anchored at two distinct locations through a pair of beams with a relatively low stiffness in the vertical direction. A comb-drive, whose fixed and moveable fingers are implemented in the same layer with a uniform thickness, is employed to create an attractive electrostatic force. This in-plane electrostatic force rotates the actuator along an axis defined by the anchors, which results in the vertical motion of a suspended platform. Due to the simple structure of the actuator, it can be readily manufactured with standard bulk micromachining processes. Experimental results demonstrate that the actuator can provide <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.02~\mu \text{m}$ </tex-math></inline-formula> of vertical displacement at a resonant frequency of 395 Hz when it is excited in air by a 10 V AC signal, while the displacement can be considerably increased in vacuum. It is further shown that the functionality of the actuator is not dependent on the type of excitation voltage; therefore, it can produce a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.09~\mu \text{m}$ </tex-math></inline-formula> static out-of-plane motion when excited by a 40 V DC voltage. A comprehensive comparison to the published works in the literature indicates that the proposed actuator is the only SOI electrostatic MEMS actuator with a relatively thick structural layer, i.e., <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~\mu \text{m}$ </tex-math></inline-formula> , that can provide out-of-plane motion at low actuation voltage reported to date. [2022-0069]

Spectroscopic, structural, and strain-dependent analysis of suspended bulk WSe2 sheets

Among the two-dimensional transitional metal dichalcogenides, tungsten diselenide (WSe2) has recently attracted a great deal of interest because of its interesting optoelectronic properties, which makes it well-positioned for a variety of electronic and quantum-optoelectronic applications. In this work, Raman spectroscopy and photoluminescence (PL) spectroscopy were utilized to analyze the phononic and electronic parameters in suspended bulk WSe2 sheets, fabricated utilizing photolithography and wet chemical etching. The optical properties such as the PL peak intensities were found to be enhanced by almost ∼4× in the suspended WSe2 regions when compared to substrate supported bulk WSe2. Additionally, temperature T-dependent Raman spectroscopy was conducted to calculate the first-order Raman temperature coefficient χ, which was determined to be lower in the suspended bulk WSe2 sheets due to the absence of substrate-induced scattering. Finally, we analyzed the modulation of Raman and PL peaks with local strain engineering from which the sensitivity of the Raman-active E2g1 mode and PL indirect I-peak in suspended bulk WSe2 were also calculated. Our work will be beneficial in analyzing thermal, optical, and mechanical properties of WSe2 in a suspended platform for its application in electronic, thermoelectric, and mechanical sensors in the future.

Quantitative assessment of the level of instability of a single-plane balance platform.

Balance training on unstable surfaces is widely used in medicine and sports. The main disadvantage of balance platforms is weakly definable assessment of the level of instability (IL) they create. To evaluate the mechanical characteristics of a suspended single-plane instability balance platform which determines quantitative instability characteristics. Three criteria influencing the IL were evaluated: 1. The displacement of the platform board by changing the position of the object on the board; 2. Amount of force required for board displacement; 3. The vibration damping of the platform. 1. 1IL the displacement of the object on the board affected 0.66 cm. the displacement of the board relative to the platform frame; 2IL - 0.79cm; 3IL - 0.91cm.; 2. A force of 2.64 is required for a board displacement of 1IL compared to 2IL and 5.76 times that of 3IL. 3. Damping factor 1IL - 0.015, 2IL - 0.006, 3IL - 0.003. 1. The longer the suspension, the change in the position of the object on the board affects the greater movement of the board relative to the platform. 2. Different IL can be compared with each other depending on how different the force required to cause the board to move. 3. The platform dampens vibrations weakly, but the damping between 1 and 3 IL differs about 5 times.

A Low-Cost High-Gain Filtering Patch Antenna Using SISL Technology for 5G Application

This letter presents a wide band high-gain filtering antenna for fifth-generation (5G) applications based on substrate integrated suspended line platform. The filtering antenna mainly consists of a driven patch, a stacked patch, and a rectangular loop. By adding a rectangular loop to the conventional patch antenna, an additional resonance can be excited. Meanwhile, the frequency selectivity of the lower band is obtained due to the formation of a radiation null. Then, a patch is stacked on the driven patch, which also generates an extra resonance mode and a radiation null at the upper band edge. Therefore, a bandpass filtering function is realized and the bandwidth is greatly improved with three resonance frequency points. The fractional bandwidth is from 4.28 to 5.34 GHz (22.04%), covering the specific 5G n79-band (4.4–5.0 GHz). Moreover, the height of the antenna is only 0.08 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the wavelength in free space of the central operating frequency), and the peak gain of the antenna is 10.4 dBi. It is worth mentioning that the whole design is low-cost since it is based on full FR4 substrates.

A compact low‐cost dual‐band bandpass filter with enhanced suppression using substrate integrates suspended line technology

AbstractA compact dual‐band bandpass filter based on the substrate integrates suspended line platform is proposed in this letter. The design is implemented using low‐cost FR‐4 material, while the loss can be reduced by 3D metal connections with substrate cutout. 0.97 dB/1.6 dB improvement of insertion loss is achieved and verified at 3.45 GHz/4.9 GHz. By paralleling quarter wavelength step impedance resonators with different operating frequencies, two paths formed between source and load. Both bandwidth and location of transmission zeros can be adjusted independently. Two stubs are added working not only as feed structure but also as a stop band resonator, which can provide 20 dB out‐of‐band suppression up to 4.4f0. The obtained performances are good enough to compare with the state of art, though very low‐cost FR‐4 materials are used.

Suspended Silicon Waveguide with Sub-Wavelength Grating Cladding for Optical MEMS in Mid-Infrared

Mid-infrared (MIR) photonics are generating considerable interest because of the potential applications in spectroscopic sensing, thermal imaging, and remote sensing. Silicon photonics is believed to be a promising solution to realize MIR photonic integrated circuits (PICs). The past decade has seen a huge growth in MIR PIC building blocks. However, there is still a need for the development of MIR reconfigurable photonics to enable powerful on-chip optical systems and new functionalities. In this paper, we present an MIR (3.7~4.1 μm wavelength range) MEMS reconfiguration approach using the suspended silicon waveguide platform on the silicon-on-insulator. With the sub-wavelength grating claddings, the photonic waveguide can be well integrated with the MEMS actuator, thus offering low-loss, energy-efficient, and effective reconfiguration. We present a simulation study on the waveguide design and depict the MEMS-integration approach. Moreover, we experimentally report the suspended waveguide with propagation loss (−2.9 dB/cm) and bending loss (−0.076 dB each). The suspended waveguide coupler is experimentally investigated. In addition, we validate the proposed optical MEMS approach using a reconfigurable ring resonator design. In conclusion, we experimentally demonstrate the proposed waveguide platform’s capability for MIR MEMS-reconfigurable photonics, which empowers the MIR on-chip optical systems for various applications.

Suspended AlGaAs waveguide for integrated nonlinear photonics

AlxGa1-xAs compound is one of the promising platforms to realize high performance nonlinear optical devices, which provide ultra-high third order nonlinearity and negligible two-photon absorption in the range of telecom wavelength. To achieve highly efficient optical confinement, the conventional AlGaAs waveguide cladding layer is achieved by using SiO2 via the wafer bonding process or AlGaAs with higher Al concentration, which requires a complex fabrication process. In this work, we demonstrate a suspended Al0.5Ga0.5As waveguide structure directly grown on the GaAs substrate by using the molecular beam epitaxy system. Both self-phase modulation and four-wave-mixing experiments are performed. By solving the nonlinear Schrödinger equations and the degenerated parametric amplification process, the n2 value is calculated to be 1.6 × 10−17 m2/W, and the nonlinear parameter is determined to be 155 W−1 m−1. As the AlGaAs thin film can be directly grown on the Si based substrate, this suspended waveguide platform could potentially be developed on a large scale silicon wafer for integrated nonlinear photonic devices.

Wideband self‐packaged antenna based on substrate‐integrated suspended line platform for 5G millimeter‐wave application

AbstractA wideband antenna based on substrate‐integrated suspended line (SISL) platform is presented for the fifth generation (5G) communication applications. The antenna is composed of two dipoles and differentially driven by coupled slot between dipole arms to achieve symmetrical radiation pattern on both E and H plane. Combining with the multilayer feature of the SISL, a metallic cavity under the dipole is formed to improve the antenna bandwidth and radiation performance. To verify the proposed antenna, one prototype was fabricated using the conventional printed circuit board process and a balun structure was designed to provide the differential excitation. The measured results indicate that the proposed dipole antenna with differential feeding network achieves a large −10 dB impedance bandwidth of 58% from 24.5 to 44.5 GHz and a peak gain of 8.2 dBi. The proposed antenna is a promising candidate for 5G communications due to its advantages of wideband, high gain, low cost, and convenient integration with differential active circuits.

A high gain solar cell aperture‐coupled patch antenna based on substrate‐integrated suspended line platform for 5G application

AbstractThe aperture‐coupled patch antenna integrated with the amorphous silicon solar cell based on the substrate‐integrated suspended line platform is presented in this letter. The antenna patch on G1 layer is used as the cathode of amorphous silicon cell and the 1 × 2 array antenna is proposed based on the unit. The solar cell antenna operating from 4.67 to 5.17 GHz has the characteristic of high gain, which is achieved by air coupling to reduce loss. The gain of the unit and array is 9.21 and 11.92 dBi, respectively. In addition, the results of the antennas with and without solar cells are little different.

Truck loading or unloading operations: Reduction of the whole-body vibration exposure of pallet truck drivers at the dock leveller location

In France, 10% of workers are exposed to whole-body vibration that can affect their health. Operators of stand-on electric pallet trucks are subjected to severe vibration on their suspended platform. Measurements in companies have shown that coming in and out of a semi-trailer when crossing a dock leveller are the most critical operations in terms of shocks and vibration. This is mainly due to floor irregularities at the loading dock area. Moreover, no standardized test code exists to assess the irregularity roughness either at the dock leveller design stage or when installed in a company. This study had dual objectives. The first was to reduce the whole-body vibration exposure of workers during truck loading or unloading. The second objective was to develop a test protocol to assess the unevenness/roughness encountered along the route, mostly around the loading dock area. In partnership with a logistics company, the operator’s activity and different loading dock areas were studied and the daily vibration exposure of drivers was calculated. Consequently, the driving habits of the drivers were changed, the surface state and uses of dock levellers were modified and the irregularities encountered, mainly at the boundary between the dock leveller and semitrailer, were treated. The reducing of daily vibration exposure by between 30% and 50% was possible with simple solutions.

Developing a Modern Greenhouse Scientific Research Facility-A Case Study.

Multidisciplinary approaches in science are still rare, especially in completely different fields such as agronomy science and computer science. We aim to create a state-of-the-art floating ebb and flow system greenhouse that can be used in future scientific experiments. The objective is to create a self-sufficient greenhouse with sensors, cloud connectivity, and artificial intelligence for real-time data processing and decision making. We investigated various approaches and proposed an optimal solution that can be used in much future research on plant growth in floating ebb and flow systems. A novel microclimate pocket-detection solution is proposed using an automatically guided suspended platform sensor system. Furthermore, we propose a methodology for replacing sensor data knowledge with artificial intelligence for plant health estimation. Plant health estimation allows longer ebb periods and increases the nutrient level in the final product. With intelligent design and the use of artificial intelligence algorithms, we will reduce the cost of plant research and increase the usability and reliability of research data. Thus, our newly developed greenhouse would be more suitable for plant growth research and production.