Bench Instrument Research Articles

Customized Multichannel Measurement System for Microbial Fuel Cell Characterization.

This work presents the development of an automatic and customized measuring system employing sigma-delta analog-to-digital converters and transimpedance amplifiers for precise measurements of voltage and current signals generated by microbial fuel cells (MFCs). The system can perform multi-step discharge protocols to accurately measure the power output of MFCs, and has been calibrated to ensure high precision and low noise measurements. One of the key features of the proposed measuring system is its ability to conduct long-term measurements with variable time steps. Moreover, it is portable and cost-effective, making it ideal for use in laboratories without sophisticated bench instrumentation. The system is expandable, ranging from 2 to 12 channels by adding dual-channel boards, which allows for testing of multiple MFCs simultaneously. The functionality of the system was tested using a six-channel setup, and the results demonstrated its ability to detect and distinguish current signals from different MFCs with varying output characteristics. The power measurements obtained using the system also allow for the determination of the output resistance of the MFCs being tested. Overall, the developed measuring system is a useful tool for characterizing the performance of MFCs, and can be helpful in the optimization and development of sustainable energy production technologies.

Fast characterization of in-plane fiber orientation at the surface of paper sheets through image analysis

The in-plane fiber orientation distribution has a decisive impact on paper mechanical and dimensional properties (e.g., tensile stiffness, hygroexpansion). It is usually estimated offline through relatively expensive bench instrumentation such as diffusion-based optical methods and ultrasonic devices. In this work we present an alternative methodology that is fast, portable, inexpensive and able to provide the complete surface polar fiber orientation profile. The proposed technology combines an image acquisition setup, consisting of a digital camera with a low angle illumination system, with the gradient-segmentation method (GSM), a robust image analysis algorithm. This camera-GSM methodology presented high internal consistency, accurately identifying the angles of samples subjected to known rotations at the imaging step. The methodology also produced comparable results to the TSO (tensile stiffness orientation) technique, used as reference. The methodology is easily transferable to plant operation, including for the online assessment of fiber orientation.

DIGITAL IMAGE CORRELATION – METHOD DEVELOPMENT, SCOPE, PRINCIPLE OF FUNCTIONING, AND FUTURE GOALS

This paper presents the basics of the Digital Image Correlation System, its algorithm of operation, methods of data recording and implementation. In addition, the paper characterises in detail the standard bench instrumentation necessary for the implementation of this type of measurement. The paper also describes the procedure of sample preparation and classifies the main methods of applying a marker to the surface of the sample. The article highlights the main advantages of the system and the main difficulties associated with its operation, and indicates the important parameters affecting the quality of the measurement. The paper shows a wide range of applications of Digital Image Correlation (DIC) and the possibilities of cooperation with other measurement systems as well as extended versions of the system, such as Digital Volumetric Correlation. The article also outlines further directions for the development of the DIC research methodology including, among others, extending the temperature range in which the method can be applied, as well as increasing the speed of camera image recording. Such modifications will allow the image correlation method to be used for research where it has not yet been possible.

Digital Impedance Emulator for Battery Measurement System Calibration.

Meaningful information on the internal state of a battery can be derived by measuring its impedance. Accordingly, battery management systems based on electrochemical impedance spectroscopy are now recognized as a feasible solutions for online battery control and diagnostic. Since the impedance of a battery is always changing along with its state of charge and aging effects, it is important to have a stable impedance reference in order to calibrate and test a battery management system. In this work we propose a programmable impedance emulator that in principle could be used for the calibration of any battery management system based on electrochemical impedance spectroscopy. A digital finite-impulse-response filter is implemented, whose frequency response is programmed so as to reproduce exactly the impedance of a real battery in the frequency domain. The whole design process of the filter is presented in detail. An analytical expression for the impedance of real battery in the frequency domain is derived from an equivalent circuit model. The model is validated both through numerical simulations and experimental tests. In particular, the filter is implemented on a low-cost microcontroller unit, and the emulated impedance is measured by means of a custom-made electrochemical impedance spectroscopy measuring system, and verified by using standard commercial bench instruments. Results on this prototype show the feasibility of using the proposed emulator as a fully controllable and low-cost reference for calibrating battery impedance measurement systems.

Flexible architecture of data acquisition firmware based on multi-behaviors finite state machine.

A flexible firmware architecture for different kinds of data acquisition systems, ranging from high-precision bench instruments to low-cost wireless transducers networks, is presented. The key component is a multi-behaviors finite state machine, easily configurable to both low- and high-performance requirements, to diverse operating systems, as well as to on-line and batch measurement algorithms. The proposed solution was validated experimentally on three case studies with data acquisition architectures: (i) concentrated, in a high-precision instrument for magnetic measurements at CERN, (ii) decentralized, for telemedicine remote monitoring of patients at home, and (iii) distributed, for remote monitoring of building's energy loss.

Development of Contact Portable Microfade Tester to Assess Light Sensitivity of Collection Items

The microfade tester is used to assess fading rates of fugitive colors of collection items. The paper presents the research considerations to design a simple, less expensive and portable contact microfade tester that could serve as a screening tool for conservators. Hardware design for such an instrument is presented that includes variations in light source (xenon or LED) and measuring head (ball lens or angled holder fiber), and does not need refocusing between measurements. Performance of the portable microfade tester versions was tested on lab samples and a paper based collection item and based on the ability to rank light sensitivity relative to that of ISO Blue Wool Standards 1, 2 or 3. The results are compared to the ranking obtained with the bench instrument when testing sensitivity of the same items for the same duration. All versions of the portable hardware were found suitable for use as a screening tool to discriminate light-sensitive collection items, with performance of the portable microfade testers using an LED optimized for samples more fugitive than Blue Wool Standard 3. These portable microfade testers need not replace the bench microfade tester as the presented portable microfade tester versions are only suitable to test collection items tolerating surface contact with the instrument.

Small Angle X-ray and Neutron Scattering: Powerful Tools for Studying the Structure of Drug-Loaded Liposomes

Nanovectors, such as liposomes, micelles and lipid nanoparticles, are recognized as efficient platforms for delivering therapeutic agents, especially those with low solubility in water. Besides being safe and non-toxic, drug carriers with improved performance should meet the requirements of (i) appropriate size and shape and (ii) cargo upload/release with unmodified properties. Structural issues are of primary importance to control the mechanism of action of loaded vectors. Overall properties, such as mean diameter and surface charge, can be obtained using bench instruments (Dynamic Light Scattering and Zeta potential). However, techniques with higher space and time resolution are needed for in-depth structural characterization. Small-angle X-ray (SAXS) and neutron (SANS) scattering techniques provide information at the nanoscale and have therefore been largely used to investigate nanovectors loaded with drugs or other biologically relevant molecules. Here we revise recent applications of these complementary scattering techniques in the field of drug delivery in pharmaceutics and medicine with a focus to liposomal carriers. In particular, we highlight those aspects that can be more commonly accessed by the interested users.

Advanced Test Solution for Data Dependent Jitter Characterization of Hsio on ATE

Jitter is the core testing spec in HSIO device characterization phase. Normally peak-to-peak jitter is measured with spec search method on ATE. But it is not sufficient due to some advanced processors require to get the knowledge of sources of deterministic jitter, especially the Data dependent jitter. In this paper, an approach for measuring the DDJ on Advantest 93K test platform is introduced, and the correlation data with bench instrumentation is shown.

Using System-like ATE to Improve the IC Design Verification

Identifying design problems as early in design cycle as possible is very critical to complete the IC design project on time and within budget. Most people today are using bench instruments, like spectrum analyzer, to validate their design in system level. These instruments are easy to setup but lack of data processing capability. On the other hand, ATE is very powerful at data collection and analysis, e.g. shmoo, data capture, and automatic test. But it's not easy to do system-like test on ATE. This paper will introduce a new solution to do system-like test on ATE, which is cost effective, and simplify the test programming on ATE. With this solution, design and verification engineer can work together to setup system-like test environment on ATE within several days, which can greatly improve the design verification efficiency and time to market.

Evaluation of portable Raman spectrometer with 1064 nm excitation for geological and forensic applications

The development of miniaturized Raman instrumentation is in demand for applications relevant to forensic, pharmaceutical and art analyses, as well as geosciences, and planetary exploration. In this study we report on evaluation of a portable dispersive Raman spectrometer equipped with 1064 nm laser excitation. Selected samples from geological, geobiological and forensic areas of interest have been studied from which the advantages, disadvantages and the analytical potential of the instrument are assessed based on a comparison with bench instrumentation and other portable Raman spectrometers using 785 nm excitation. It is demonstrated that the instrument operating with 1064 nm excitation has potential for expanding the number and types of samples that can be measured by miniaturized Raman spectroscopy without interfering fluorescence background emission. It includes inorganic and organic minerals, biomolecules within living lichen and endolithic cyanobacteria as well as drugs of abuse and explosives.

Evaluation of portable Raman instrumentation for identification of β-carotene and mellitic acid in two-component mixtures with halite

Recently, portable Raman instrumentation has been in demand for geosciences and for future planetary exploration for the identification of both organic and inorganic compounds in situ on Earth and on other planetary bodies, especially on Mars. Here we present the results of the analysis of halite/β-carotene and halite/mellitic acid mixtures, performed by miniaturized Raman instrumentation equipped with 785 and 1064 nm excitation. Various proportions of organics in the halite matrix were examined. The lowest concentration of β-carotene detected using the 785 nm laser was 1 mg kg −1, with slightly better signals observed with shorter exposure times compared with the bench instrument using the same excitation wavelength. Mellitic acid was identified at the concentration level 10 g kg −1. The 1064 nm excitation provided a lower sensitivity towards low concentration when compared with the 785 nm excitation.

Towards early dental caries detection with OCT and polarized Raman spectroscopy

In recent years, we have been developing optical coherence tomography (OCT) and polarized Raman spectroscopy (PRS) for the detection of early non-cavitated dental caries. OCT provides high resolution morphological depth imaging of incipient caries. With OCT, early lesions can be readily identified as regions of high light backscattering with depth into the enamel as compared to health sound enamel. From the OCT images, the lesion depth can be approximated to provide clinically useful information to guide treatment decisions. In addition, we have derived a parameter known as the optical attenuation coefficient in order to distinguish sound from carious enamel non-subjectively. OCT is being combined with PRS since regions of high light backscattering not related to caries development can lead to false-positive results. PRS provides biochemical specificity along with molecular structural/orientational information. With PRS, the Raman depolarization ratio calculated from the main phosphate vibration at ~959 cm-1 from parallel- and cross-polarized Raman spectra allows discrimination between sound and early developing caries. Early studies on lab bench instrumentation are now being translated into fibre-optic based devices for intra-oral use in patient volunteers for clinical validation. In combination, OCT and PRS have potential for detecting and monitoring early lesions with high sensitivity and high specificity.

Experimental Study of an Adding Interferometer at Millimeter Waves

In order to study an original detection architecture for future cosmology experiments based on wide band adding interferometry, we have tested a single baseline bench instrument based on commercial components. The instrument has been characterized in the laboratory with a wide band power detection setup. A method which allows us to reconstruct the complete transfer function of the interferometer has been developed and validated with measurements. This scheme is useful to propagate the spurious effects of each component till the output of the detector.

Portable Equipment for Luminescence Lifetime Measurements on Surfaces

The prototype of a portable instrument, based on the time-correlated single-photon counting method, purposely assembled for in situ measurements of luminescence lifetimes on artwork surfaces, is here presented. Preliminary tests have been carried out using the portable instrument and the results have been compared with those obtained using a bench instrument. In this way we have proven that the prototype provides lifetime measurements with good precision. It is also shown that fluorescence lifetime determinations, coupled with steady-state fluorescence spectra, allow the distinguishing, on laboratory samples, of different red organic lakes having similar fluorescence spectra, achieving new boundaries in the nondestructive diagnosis of artwork materials. The first in situ application of the technique on an original work of art, The Book of Kells, held at Trinity College Library, Dublin, highlighted the diagnostic potential of coupled steady-state and time-resolved luminescence spectroscopy in the identification of organic colorants.

Prototype optical bench instrument in the interferometer for the LISA–Pathfinder space mission

In preparation for the Laser Interferometer Space Antenna (LISA) space mission, the prototype engineering model of the LISA-Pathfinder optical bench instrument has been built and tested. The instrument is the central part of an interferometer whose purpose is to measure the separation of two free-floating test masses in the spacecraft, with required accuracy to a noise level of 10 pm/Hz?1/2 between 3 mHz and 30 mHz. This will allow the spacecraft to achieve drag-free flight control to a similar level, as a demonstration of technology capability for detection of gravitational waves in the later LISA mission. The optical bench design, fabrication, and experimental results are described in detail, with attention to the strategies for building and alignment. These are particularly problematic in this instrument due to restrictions on the allowable materials and devices, the limited size, the tight alignment requirements for interferometry and interfaces, and the challenging environment specification for space flight. The finished optical bench was integrated to the complete optical metrology package for system-level tests, which were successful, both in meeting the metrology accuracy and in environmental testing. This verifies the feasibility of the design and build methods demonstrated here for use in the space-flight version.

An optical DNA-based biosensor for the analysis of bioactive constituents with application in drug and herbal drug screening

The efficient and rapid detection of bioactive compounds in complex matrices of different origins (natural or synthetic) is a key step in the discovery of molecules with potential application in therapy. Among them, molecules able to interact with nucleic acids can represent important targets. In this study, an optical DNA biosensor, based on surface plasmon resonance (SPR) transduction, has been studied in its potential application as new analytical device for drug screening. This device was applied to the analysis of pure synthetic or natural molecules and also to some fractions obtained by chromatographic separation of an extract of Chelidonium majus L. (great celandine), a plant containing benzo[ c]phenanthridinium alkaloids having intercalating properties. The ability of these molecules to interact with the double stranded nucleic acid (dsDNA) immobilised on the sensor surface has been investigated. The optical sensing relies on the SPR-based bench instrument Biacore X™ and represents an example of multiuse sensor. The results obtained demonstrate the potential application of this device for the rapid screening of bioeffective compounds. The characteristics of the biosensor offer the possibility to be coupled to chemical analysis as in hyphenated technologies.

Dc and ac optical nulling bridges for sensitive transmittance measurements

We present a formal comparison between dc and ac nulling optical bridges. We consider their performance in monitoring over long periods of time (several minutes), small and slow (in a time scale of seconds) changes in transmittance of an optical component. We consider two fundamentally different ac optical bridges (OB), an amplitude modulated optical bridge (AM-OB), and a switching optical bridge (Sw-OB). For each OB, we derive a general expression for the minimum detectable change in transmittance (|ΔT|min), taking into account all the important noises. It is found that under optimum conditions the dc- and AM-OB have similar detection limits imposed by the 1/f noise of the photodetectors. It is shown that the Sw-OB can in principle overcome the 1/f noise of the detector and approach the shot-noise limit; however, it is sensitive to switching device imperfections (to first order in smallness), which could easily prevent achieving a detection limit below the 1/f noise. It is also shown that the Sw-OB has intrinsic advantages over the dc- and AM-OB for its use in remote sensors. It can eliminate more efficiently noise induced along the propagation of light from the sensing point to the photodetector. We conclude that when using low power optics (P⩽1 mW) and considering a bench instrument, the dc- and AM-OB can be used for a target resolution down to |ΔT|min≈10−5–10−6. The Sw-OB optical bridges should be chosen if |ΔT|min≈10−6–10−8 is to be attempted. In any case, strict conditions are to be met before considering approaching the detection limits imposed by electronic noises. These conditions are discussed in detail. In particular, atmospheric isolation will be needed in general below |ΔT|min≈10−4.

Jitter measurement of an ADC by statistical analysis

Abstract A method for measuring the jitter of an ADC based on the ‘lcked histogram’ test is presented, and the conditions for validation of the test as a function of the sampling position is studied. As all test bench instruments have their own independent jitter a mathematical model is used to extract the jitter of the ADC. Some experimental results are given.

Instrumentation: Bench instruments are linked by personal computers and the steps in devising chip tests and designing chips are linked by software

A review of developments during 1984 shows that personal computers strengthened their foothold in the instrumentation field. New programs to acquire and analyze data became available for applications ranging from repairing computers to controlling manufacturing instruments. Computer-aided design and test software for test workstations is linking the task of writing test programs, simulating circuits, documenting test specifications, and debugging test programs. Many of these tasks, previously available only on separate programs, are being done with one software package. In addition, bench instruments improved last year with the introduction of several new products, bringing prices lower and making more portable instruments available.

Instrumentation. II. Laboratory/bench units

For pt.I see ibid., vol.18, no.1, p.66 (1981). Discusses laboratory, production and bench instruments with regard to speed and versatility, including automated test equipment.