Characterization Setup Research Articles

Development of a Simple Setup to Measure Shielding Effectiveness at Microwave Frequencies.

Testing the shielding effectiveness of materials is a key step for many applications, from the industrial to the biomedical field. This task is very relevant for high-sensitivity sensors, whose performance can be greatly affected by electromagnetic fields. However, the available testing procedures often require expensive, bulky, and heavy measurement chambers. In this paper, a cost-effective and reliable measurement procedure for testing the shielding effectiveness of materials is proposed. It exploits a lab-scale anechoic shielded chamber, which is lightweight, compact, and cost-effective if compared to the available commercial solutions. The measurement procedure employs a vector network analyzer to allow an accurate and fast characterization setup. The chamber realization phases and the measurement procedure are described. The shielding capability of the chamber is measured up to 26 GHz, whereas the performance of commercial shielding coatings is tested to demonstrate the measurement's effectiveness.

Modular multi-channel high voltage arbitrary waveform generator and imaging setup for dielectric elastomer actuator characterisation

Various applications require multi-channel high-voltage sources for their control, e.g. electrostatic adhesion, electrophoresis and artificial muscles such as piezoelectric, hydraulically amplified self-healing electrostatic(HASEL) and dielectric elastomer actuators(DEAs). Further, the ability to simultaneously monitor the state of the actuators either with images, or voltage and current sensing is crucial to characterise their behaviour. In this work, we present the design of a versatile characterisation setup, capable of generating eight HV (15 kV) arbitrary waveforms(rise time of 8 ms and fall time of 80 ms for 60 MΩ load), while synchronously monitoring voltage and current, and record high-speed (120 fps) video. The setup ensures modularity and customisability by consisting of three independent modules: (1) The imaging module includes a Raspberry Pi and a Pi Camera; (2) A 3.3 V analogue interface 16-bit resolution data acquisition module on a PCB that accommodates a microcontroller board, two 8-channel analogue-to-digital converters, and an 8-channel digital-to-analogue converter; (3) Up to 8 DC-to-HVDC converter boards powered by 12 V DC, with 3.3 V analogue interface.

Differences Between NSA 94–106 and IEEE Std. 299 Setups for Low-Frequency Magnetic Shielding Effectiveness Characterization: A Study Using Numerical Simulations

Differences Between NSA 94–106 and IEEE Std. 299 Setups for Low-Frequency Magnetic Shielding Effectiveness Characterization: A Study Using Numerical Simulations

Chemical insights into ethyl acetate flames from experiment and kinetic modeling: Laminar burning velocity, speciation and NOx emission

Oxygenated fuels, such as alcohols, ethers, and esters, are promising alternatives to conventional fuels. These fuels can help reduce detrimental emissions like carbon monoxide and unburned hydrocarbons and enhance octane ratings. Among these oxygenates, ethyl acetate (EA), a small alkyl ester sourced from biomass, emerges as a clean, promising energy carrier. It serves as a surrogate fuel to facilitate investigations into the combustion behaviours of biodiesel. Despite its importance, the literature knowledge of EA combustion characteristics is limited. Therefore, this study aims to broaden the knowledge of the combustion behaviour of this type of oxygenated fuel compound. In this study, we measured the laminar burning velocities of EA by employing a heat flux burner and a closed combustion vessel over the equivalence ratios of 0.7 – 1.7, pressures of 1 – 10 bar and temperatures ranging from 353 – 423 K. Further, we also measured the NOx emissions in exhaust gas of the premixed flames fueled by EA/air for the first time over the equivalence ratio of 0.8 – 1.2. Additionally, we employed a non-premixed counterflow flame setup for extensive characterisation of species and their concentration under diverse conditions encompassing various strain rates and oxygen concentrations. Finally, we utilized these newly measured data to construct and validate a detailed kinetic model developed as part of this work. The newly developed model will help characterize the combustion properties of EA.

Design principles of operando ultraviolet-visible and electron paramagnetic resonance spectroscopy setups for active site characterization in ion-exchanged zeolites

Cu- and Fe-exchanged zeolites have been widely investigated for their applicability in selective partial oxidation of CH4 and abatement of environmentally harmful nitrogen oxides. However, the differentiation between spectator and active sites is cumbersome due to their dynamic co-existence, which aggravates the elucidation of the redox dynamics of the latter. Therefore, correlated multi-spectroscopic approaches carried out under operando conditions are needed in order to disentangle the inherent reactivity of specific species. Here we describe the conceptualization of complementary operando spectroscopic methods for the investigation of ion-exchanged zeolites employed in redox reactions. The potential and versatility of this approach are demonstrated by means of two exemplary case studies. First, we present the insight generated by two custom operando ultraviolet-visible and electron paramagnetic resonance spectroscopy setups operating in batch mode into CH4-to-CH3OH conversion over Cu-exchanged mordenite. In addition to recording the method-dependent spectroscopic fingerprints of distinct Cu centers, the overall CH4 consumption is simultaneously monitored in both setups. The extracted apparent activation energies of the reactive centers obtained from the two systems are in good agreement with each other allowing to link the bulk reactivity to the intrinsic site-specific kinetics of all Cu centers. Second, the EPR setup is equipped with a flow reactor designed to carry out modulated excitation experiments with phase-sensitive detection in order to improve the signal-to-noise ratio and time resolution. The cell is employed to study the conversion of NO via selective catalytic reduction over Fe-exchanged ferrierite. In combination with operando X-ray absorption spectroscopy, a small portion of active Fe species consisting of monomers in gamma-positions and oligomeric structures located in the main channel is identified, which are kept in a redox active state under relevant reaction conditions and thus sustain the chemical transformation of NO.

On Iterative Pre‐Compensation of 3D Laser‐Printed Micro‐Optical Components Using Confocal‐Optical Microscopy

AbstractState‐of‐the‐art 3D two‐photon laser printing systems already use pre‐compensation algorithms to reduce systematic deviations between the printed and the targeted structures. Nevertheless, the remaining deviations are often still larger than the uncontrollable or “statistical” deviations. In principle, it is straightforward to correct for systematic deviations by measuring the difference between printed structure and target and by subtracting the difference from the first target to obtain the next‐iteration target. However, in reality, one faces several issues such as noise and systematic errors of the characterization measurement itself, as well as unwanted translations and rotations between the coordinate systems of the characterization setup and the printer, respectively. Two examples of printed structures requiring sub‐micrometer accuracy are considered, a large 1D micro‐lens array and a specific diffractive optical element. For both, the device performance before the pre‐compensation workflow described herein is insufficient for the targeted application and has become sufficient after this workflow. The workflow involving optimizations using cross‐correlations with confocal‐optical‐microscopy data is documented by an open‐access program (available via GitLab). This program includes an easy‐to‐use graphical user interface so that other researchers can immediately profit from it.

Terahertz characterization of combined pressure-shear shock loaded aromatic polyurea

Realistic shock loading scenarios imply combined, multiaxial stress states, where the mechanically induced energy competes for failing the material intrinsically due to cohesive failures. Under shock loading, failure encompasses various modes, including spallation, shear bands, microcracking, morphological alteration, phase transformation, and plastic deformation. However, elucidating failure in high strain loading conditions challenges the state-of-the-art characterization due to the disparity interfacing different loading and measurement techniques. This research used a novel spectro-mechanical characterization setup, integrating bulk terahertz spectroscopy synchronized in real-time with mixed-mode laser-induced shock waves. The latter was used to submit polyurea elastomers to concurrent pressure and shear waves by saddling a thin polymer sheet on the hypotenuse of a glass prism. Hence, the laser-induced pressure shock waves underwent simultaneous mode conversion at the glass-polyurea interface at the hypotenuse of the glass prism, effectively submitting the sample to tunable amplitude pressure-shear shock waves. The terahertz spectroscopy, operating in the right-angle reflection configuration, was modified to probe predetermined spots on the polyurea samples at different stress states (adjusted by changing the illumination energy) in a three-step sequence: before, during, and after shock loading. The shock-loaded polyurea samples were also characterized using the optical and scanning electron microscopes, revealing compression-shear and tensile-shear failure modes, including surface depression, nucleation of micro-voids and microcracks, and formation of small planes. The induced stress state based on the illumination energy was quantified using an accompanying finite element simulation, resulting in completing the quasi-isentropic behavior of polyurea elastomers, which was found to be in good agreement with previous experimental data from the plate impact experiments and the predictions based on the Lennard-Jones potential. Time domain analysis of terahertz data, using temporal shifting, hysteresis, and dynamic time warping based on the sum of the Euclidean distances between signal pairs, affirmed the microscopy observations while shedding insights on the elastic and plastic deformations and the reversible conformational changes. Irreversible changes to the macromolecule were also detected using the terahertz data spectral analysis. The current results establish a new experimental framework for fundamentally characterizing polymers and their composites at ultrahigh strain rate loading conditions.

Development of a low-medium temperature T-history setup for the thermal storage characterization of non-homogeneous mixtures containing PCMs

More attention has been paid to thermal energy storage in recent years for its advantages in heating and cooling applications to foster the use of renewable energies. As part of the design of new thermal energy storage materials, the characterization of specific heat capacity and phase change enthalpy is required. One of the most widespread methods for evaluating specific heat capacity and phase change enthalpy is differential scanning calorimetry (DSC). However, the small amount of required material means that DSC is not the most suitable method for non-homogeneous materials. This paper presents the development and validation of a low-medium temperature (<100 °C) T-history system for measuring specific heat capacity and phase change enthalpy as an economical alternative. Validation was carried out with paraffins used as phase change material and two data processing methods were applied. Only one of the methods was able to measure the specific heat capacity in the liquid and solid phases, and the phase change enthalpy. Acceptable deviations calculated as the relative error in relation to DSC and manufacturer values were obtained with values lower than 18.50 % and 14.58 % respectively. The new system was used to evaluate the thermal properties of a pure paraffin/water emulsion and a hybrid carbon-paraffin/water emulsion by corroborating its suitability for measuring non-homogeneous samples.

Fast and inexpensive emission-time in-situ setup for upconversion nanoparticle characterization

In this work, a straightforward analytical approach is presented for the evaluation of the entire time-resolved emission spectrum of Er3+-doped upconversion nanoparticles (UCNP) by the acquisition of bidimensional emission wavelength-time signals. Employing diffractive optics and fast optomechanical sweeping, the entire emission wavelength-time matrix (EtM) of UCNP is registered. An optic fibre probe allows the measurement of micrometric-size domains in surfaces, either in solid form or in suspension. Further chemometric analysis was also performed to gain further insight into the behaviour of the emission bands and their corresponding time curve profiles. To show the applicability of the developed procedure, changes either in the emission spectrum or the time behaviour by external perturbations were monitored and EtM at different temperatures was acquired as a proof of concept. The results demonstrated the effectiveness of the proposed procedure in obtaining fast and highly informative images and enlightening knowledge about the phosphorescence-based system.

Development of a test setup for hydrodynamic characterization of hydrocephalus shunts

Abstract Implantation of a shunt system is the most common neurosurgical procedure for the treatment of hydrocephalus. Hydrodynamic parameters of hydrocephalus shunt systems are valuable variables to address patients' needs. In this report, we present a test setup to evaluate hydrodynamic parameters of hydrocephalus shunt systems. The test setup was validated using a stainless steel capillary and compared with the analytical solution according to Bernoulli's equation. It was demonstrated that the experimental setup is able to model the pressure in a physiologically relevant range. The measured and averaged flow resistance was 2.96 mmHg/(ml min-1). According to the analytical solution of Bernoulli's equation, the flow resistance is 2.86 mmHg/(ml min-1). Therefore, the measured flow resistance is 3.5% higher than the analytical solution. Moreover, the nonlinear characteristic of the pressure drop at the inlet and outlet of the capillary plays a minor role compared to the friction of the tube flow. As a result, the increase in flow rate with increasing pressure load can be well approximated by a linear function for the low flow rates measured here. The experimental setup presented will be used in the future to characterize commercially available shunt systems under various hydrodynamic conditions.

Low Inductive Characterization of Fast-Switching SiC MOSFETs and Active Gate Driver Units

Accurate switching device characterization is necessary for effectively utilizing the technological ad-vantages of Silicon Carbide (SiC) Power Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) over their Silicon (Si) Insulated-Gate Bipolar Transistor (IGBT) counterparts. With switching times of few nanoseconds, the unprecedented switching speed of SiC semiconductor devices challenges today's converter and characterization setup designs in regard to parasitic layout inductances for optimal conversion and reliable characterization data. Fur-thermore, active gate driving is a key to unlock the potential of SiC MOSFETs, but requires performance assessment prior to integration. This paper presents a low-inductive test platform for flexible and high-accuracy characterization of fast-switching SiC MOSFETs and active gate drivers evalu-ation. The test circuit delivers high quality characterization data that is comparable with a commercial dynamic power device characterizer. In addition to the conventional hard-switching double-pulse tests with a two-level voltage source gate driver, the test circuit offers soft-switching and gate driver evaluation capability in addition. This test platform is a valuable tool for obtaining reliable characterization data to develop more accurate SiC MOSFET simulation models, and evaluate the combination of gate driver and MOSFET prior to the prototyping phase of a converter.

Design, assembly and start-up of an experimental set-up for optical characterization in biological tissues

Design, assembly and start-up of an experimental set-up for optical characterization in biological tissues

Monolithic PneuNets Soft Actuators for Robotic Rehabilitation: Methodologies for Design, Production and Characterization

Soft-robotics for biomedical applications, such as rehabilitation robots, is a field of intense research activity. Different actuation solutions have been proposed in the last decades, involving study and development of soft actuators of different types and materials. The purpose of the paper is to present procedures for an optimized design, and for easy and low cost production and characterization of monolithic PneuNets soft-actuators. An innovative design approach has been developed. The parameterization of the geometry, combined with FEM simulations is the basis for an optimized design of the actuator, as a function of the obtained bending and of the generated forces. Simple and cheap characterization setup and procedures have been identified for the actuator characterization and for simulation results validation. An easy and low-cost fabrication method based on lost wax core obtained through a silicone based mold has been developed for a monolithic PneuNets soft-actuator. The proposed solution performs well in bending, without the need for a strain limiting layer. Experimental results validated simulations, confirming the feasibility of adopting an optimized simulation-based design approach.

Simple experimental method to determine the specific heat capacity of cylindrical Lithium-Ion-Battery cells

This study presents a new method for determining the specific heat capacity of cylindrical Lithium-Ion-Battery (LIB) cells. In comparison to other available methods, the developed procedure is simple, cost-efficient, non-destructive and reliable. The experimental setup only requires a standard LIB power characterization setup and one additional heat flux sensor (HFS). The HFS is wrapped around the studied sample and the sample is suspended in the middle of a climate chamber. The specific heat capacity can be determined by increasing the climate chamber temperature by ΔT=5K while continually measuring the temperature and heat flux. The method has been validated with an Al7075 cylindrical sample, showing deviations in the specific heat capacity compared to the results with a differential scanning calorimeter (DSC) of 0.35%. Further validation of the developed method has been achieved for a nickel manganese cobalt (NMC) cell, having a mean error of −0.37% compared to the mass-weighted-average method. Additionally, the method has been used to determine the specific heat capacity of a nickel cobalt aluminum (NCA) and lithium iron phosphate (LFP) LIB cell. While the dependency of the specific heat capacity on the State of Charge (SOC) seems to be neglectable (maximum deviation 2.29% in a LFP-cell), the temperature dependency (maximum 0.23%K−1 for NCA/NMC-cell) should be considered for the thermal modeling of LIBs.

A Corrugated Planar-Goubau-Line Termination for Terahertz Waves

The planar Goubau line is a promising low-loss metal waveguide for terahertz interconnects. To enable advanced system architectures and multi-port measurements based on planar Goubau lines, there is a strong need for broadband impedance-matched loads, which can be used to absorb the energy and minimize standing waves in a system. In this work, we propose a matched load for planar Goubau lines based on an exponentially-tapered corrugated line, gradually increasing conductor losses while maintaining small reflections. The corrugation density is high enough to increase conductor losses without requiring an auxiliary low-conductivity material, simplifying the fabrication process. A 400-$\mu$m long planar Goubau line load was fabricated on a 10-$\mu$m thick silicon substrate suspended in the air. Electromagnetic simulations of the load show excellent agreement with calibrated reflection measurements in the frequency range 0.5 THz - 1.1 THz. Above the cut-off frequency of around 580 GHz, the measured reflections are much less than -19 dB, below the noise floor of the characterization setup.

Signal and Power Integrity IO Buffer Modeling Under Separate Power and Ground Supply Voltage Variation of the Input and Output Stages

This work presents an improved input–output (IO) buffer model for signal and power integrity simulation, including power/ground supply voltage (PGSV) variations for the buffer’s input and output stages. Both stages are mathematically modeled from a formulation that is derived from nonlinear electrical circuit analysis, an important aspect that grants these models a good level of generality and, simultaneously, high accuracy. The proposed IO buffer model is linear in the parameters and, therefore, extractable through the linear least-squares technique from the signals acquired in an IO buffer characterization setup. Several validation scenarios, supported on two CMOS driver’s transistor technologies, are performed to evaluate the accuracy of the proposed model. In addition, a comparative analysis is provided, confronting the proposed model’s performance against that of the input/output buffer information specification (IBIS) model, evidencing an outstanding modeling improvement provided by the proposed model.

Magnetic cleanliness verification of miniature satellites for high precision pointing

The advancement in miniature satellite technology and its increasing usage in scientific and commercial applications presents new and unique challenges, particularly for pointing requirements. These small platforms, often limited in resources, are particularly susceptible to disturbance from residual magnetic dipoles while operating in low earth orbit (LEO). To overcome this issue, the precise identification of a satellite's residual magnetic dipole is crucial to enable the compensation of disturbance torques. However, the use of magnetic materials in modern commercial-off-the-shelf (COTS) technology cannot always be avoided. The pre-launch verification of magnetic cleanliness requirements in a laboratory setting is also a significant challenge for small satellite systems. To address this problem, Fraunhofer Ernst-Mach-Institute (EMI) and Fraunhofer Institute for Physical Measurement Techniques (IPM) have developed a cutting-edge test setup for the precise characterization of small residual dipole moments, with the goal of qualifying the ERNST nanosatellite. This innovative approach aims to provide efficient system verification with minimal time and cost overhead and to establish a dedicated test infrastructure, specifically tailored to tackle the unique challenges and requirements of magnetic cleanliness verification in future miniature space systems. As a promising preliminary result of the first test campaign, the filter wheel mechanism of the ERNST nanosatellite could be optimized, resulting in a significantly reduced magnetic moment of the device, meeting the missions challenging magnetic budget constraints.

A Reconfigurable Setup for the On-Wafer Characterization of the Dynamic RON of 600 V GaN Switches at Variable Operating Regimes

Charge-trapping mechanisms observed in high-voltage GaN switches are responsible for the degradation of power converter efficiency due to modulation of the effective dynamic ON-resistance (RON) with respect to its static value. Dynamic RON degradation is typically dependent on the blocking voltage and the commutation frequency and is particularly significant in new technologies under development. The possibility to characterize this phenomenon on GaN switch samples directly on-wafer, under controlled operating conditions that resemble real operations of the DUT in a switching mode power converter is extremely valuable in the development phase of new technologies or for quality verification of production wafers. In this paper, we describe a setup that allows this characterization: dynamic RON degradation of on-wafer 600 V GaN switches is characterized as a function of the VDS blocking voltage, the VGS driving voltage, and at different temperatures. The dependency on the switching frequency is identified by measuring the current recovery of the switch after the application of blocking voltages of different durations.

High‐Temporal‐Resolution Characterization Reveals Outstanding Random Telegraph Noise and the Origin of Dielectric Breakdown in h‐BN Memristors

AbstractMemristor‐based electronic memory have recently started commercialization, although its market size is small (~0.5%). Multiple studies claim their potential for hardware implementation of artificial neural networks, advanced data encryption, and high‐frequency switches for 5G/6G communication. Application aside, the performance and reliability of memristors need to be improved to increase their market size and fit technology standards. Multiple groups propose novel nano‐materials beyond phase‐change, metal‐oxides, and magnetic materials as resistive switching medium (e.g., two‐dimensional, nanowires, perovskites). However, most studies use characterization setups that are blind to critical phenomena in understanding charge transport across the devices. Here an advanced setup with high temporal resolution is used to analyze current noise, dielectric breakdown growth, and ambipolar resistive switching in memristors based on multilayer hexagonal boron nitride (h‐BN), one of the most promising novel nano‐materials for memristive applications. The random telegraph noise in pristine memristors and its evolution as the devices degrade, covering ~7 orders of magnitude in current with consistent observation, is studied. Additionally, an ambipolar switching regime with very low resistance down to 50Ω and its connection with a telegraph behavior with high/low current ratios &gt;100, linked to a thermally‐driven disruption of a metallic nanofilament, is shown.

Experimental setup for high-resolution characterization of crystal optics for coherent X-ray beam applications.

Stanford Synchrotron Radiation Lightsource serves a wide scientific community with its variety of X-ray capabilities. Recently, a wiggler X-ray source located at beamline 10-2 has been employed to perform high-resolution rocking curve imaging (RCI) of diamond and silicon crystals. X-ray RCI is invaluable for the development of upcoming cavity-based X-ray sources at SLAC, including the cavity-based X-ray free-electron laser and X-ray laser oscillator. In this paper, the RCI apparatus is described and experimental results are provided to validate its design. Future improvements of the setup are also discussed.