A flexible thin-film for powering stand alone electronic devices

This paper presents a flexible thin-film (FTF) composed by a photovoltaic (PV) cell, a flexible solid-state rechargeable battery and power management electronics. A flexible printed circuit board (fPCB) was used for providing physical support to the electronics and to the battery, whereas a PDMS (polydimethylsiloxane) layer was used for providing mechanical adhesion between the PV cell and the fPCB. The high elasticity of the PDMS makes this material an excellent candidate for adapting two materials with different thermal expansions (fPCB and PV). The physical measurements showed a prototype with a thickness in the range 1.52 ± 0.10 mm, 10 g of weight and 37 × 114 mm of size. The electrical measurements showed ability to provide an output voltage of 3.8 V in a continuously form under these conditions: the PV providing DC power for solar irradiations higher than 6 W m⁻², and the battery providing DC power for solar irradiations above bellow 6 W m⁻² (value that has emerged during the twilight between sunset and dusk).     

A force-matching method for quantitative hardness measurements by atomic force microscopy with diamond-tipped sapphire cantilevers

We present a new method to improve the accuracy of force application and hardness measurements in hard surfaces by using low-force (<50 μN) nanoindentation technique with a cube-corner diamond tip mounted on an atomic force microscopy (AFM) sapphire cantilever. A force calibration procedure based on the force-matching method, which explicitly includes the tip geometry and the tip-substrate deformation during calibration, is proposed. A computer algorithm to automate this calibration procedure is also made available. The proposed methodology is verified experimentally by conducting AFM nanoindentations on fused quartz, Si(1 0 0) and a 100-nm-thick film of gold deposited on Si(1 0 0). Comparison of experimental results with finite element simulations and literature data yields excellent agreement. In particular, hardness measurements using AFM nanoindentation in fused quartz show a systematic error less than 2% when applying the force-matching method, as opposed to 37% with the standard protocol. Furthermore, the residual impressions left in the different substrates are examined in detail using non-contact AFM imaging with the same diamond probe. The uncertainty of method to measure the projected area of contact at maximum force due to elastic recovery effects is also discussed.     

Noise characteristics of high-frequency,short-duration GPS records from analysis of identical,collocated instruments

High-rate (>1 Hz) GPS, currently used for measurement of dynamic processes and as a universal time and frequency standard, is usually assumed to be affected by site-specific errors and only limited studies of the error properties of high-frequency (10 Hz), short-duration (<100 s) GPS records exist. Preliminary studies, provided evidence of instrument-specific errors, which were investigated on the basis of systematic experiments with various types of stationary, collocated, identical GPS units. This analysis revealed differences between couples of receiver/antenna units, while spectral analyses revealed low-frequency colored noise, statistically significant below 0.2 Hz and, gradually decaying with increasing duration of observations, so that above 2.5 Hz measurements are contaminated only by white noise.     

Effect of analysis direction on the measurement of interfacial mixing in thin metal layers with atom probe tomography

The accuracy and precision of thin-film interfacial mixing as measured with atom probe tomography (APT) are assessed by considering experimental and simulated field-evaporation of a Co/Cu/Co multilayer structure. Reconstructions were performed using constant shank angle and Z-scale reordering algorithms. Reconstruction of simulated data (zero intermixing) results in a 10-90% intermixing width of ∼0.2 nm while experiential intermixing (measured from multiple runs) was 0.47±0.19 and 0.49±0.10 nm for Co-on-Cu and Cu-on-Co interfaces, respectively. The experimental data were collected in analysis orientations both parallel and anti-parallel to film growth direction and the impact of this on the interfacial mixing measurements is discussed. It is proposed that the resolution of such APT measurements is limited by the combination of specimen shape and reconstruction algorithms rather than by an inherent instrumentation limit.     

An efficient cardiac signal enhancement using time–frequency realization of leaky adaptive noise cancelers for remote health monitoring systems

Nowadays telecardiology is an important tool in cardiac diagnosis from a remote location. During Electrocardiogram (ECG) or Cardiac Signal acquisition several artifacts strongly affect the ST segment, degrade the signal quality, frequency resolution, produce large amplitude signals in ECG that can resemble PQRST waveforms and mask the tiny features that are important for clinical monitoring and diagnosis. So the extraction of high-resolution cardiac signals from recordings contaminated with artifacts is an important issue to investigate. In this paper, various novel block based time–frequency domain adaptive filter structures for cardiac signal enhancement are presented. These filters estimate the deterministic components of the cardiac signal and remove the noise component. The Block Leaky Least Mean Square (BLLMS) algorithm, being the solution of the steepest descent strategy for minimizing the mean squared error in a complete signal occurrence, is shown to be steady-state unbiased and with a lower variance than the LMS algorithm. To improve the filtering capability some variants of BLLMS, Block Normalized LLMS (BNLLMS) and Block Error Normalized LLMS (BENLLMS) algorithms are implemented in both time domain (TD) and frequency domains (FD). Finally, we have applied these algorithms on real cardiac signals obtained from the MIT-BIH data base and compared their performance with the conventional LLMS algorithm. The results show that the performance of the block based algorithms is superior to the LLMS counterparts in terms of signal to noise ratio improvement (SNRI), excess mean square error (EMSE) and misadjustment (M). Among all the algorithms FDBENLLMS achieves higher SNRI than other techniques. These values are 25.8713 dB, 20.1548 dB, 21.6718 dB and 20.7131 dBs for power line interference (PLI), baseline wander (BW), muscle artifacts (MA) and electrode motion artifacts (EM) removal.     

Novel: Time optimization model for centrifugation process: Application in human blood-plasma separation

One way to accurately diagnose many human diseases is to conduct tests on a sample of blood. These tests are based on analyzing precisely the results of a blood plasma sample free from any other blood cells. This article develops a mathematical model for the separation efficiency of laboratory centrifuge controller. Multi-decay power pulses through a blood sample to determine separation efficiency that provides accurate attenuation measurements. Ultrasonic attenuation measurements were obtained for human blood-plasma of 1 ml volume for concentrations of 20%, 35%, 55%, 80% and 95% plasma by weight. The separation efficiency measurements were obtained for a time period of 5 min divided into 0.5 min.     

Metrological characterization of the new 1 MN force standard machine of NPL India

Since November 2010, NPL India’s force scale has been complemented in the range from 10 kN to 1 MN by a further force standard machine. This automatically working 1 MN force standard machine utilizes a lever amplification of a 100 kN mass stack and enables low relative expanded uncertainties of smaller than 9 × 10⁻⁵ on the lever, and 2 × 10⁻⁵ on the deadweight side. In this paper, the constructional design of the machine is described. According to the new EURAMET Calibration Guide, a model for the uncertainties is developed.Supplementary to this, results from comparison measurements of the new NPL India machine with PTB´s force standard machines are presented.     

Surface finishing of flat pieces when submitted to lapping kinematics on abrasive disc dressed under several overlap factors

In machining of pieces that require surface finishing levels finer than grinding can offer, it is necessary to use specific finishing processes. However, these processes, which have lapping as the most classic representative, are usually difficult to setup and demand much time in setting the large number of variables. This paper discusses the investigation of an abrasive process for finishing of flat workpieces based on the combination of important grinding and lapping characteristics. Instead of loosing abrasive grains between the workpiece and the lapping plate, a resinoid grinding wheel of hot-pressed silicon carbide is fixed on the plate of a device resembling to a lapping machine. The grinding wheel is dressed with a single-point diamond for maintaining its form flat and mainly for interfering in the workpieces surface finishing by varying of the overlap factor (Ud). It was noticed that the studied process can simplify the setup and make it easier than in lapping, which is a painstaking process. The surface roughness values and flatness deviations showed to be comparable to those achieved in lapping, or even better. The best surface roughness and flatness deviation found were Ra = 0.8 nm and 0.4 μm with Ud = 3, respectively. The workpiece material was made of quenched and tempered SAE 4340 steel, reaching a hardness of 60 HRC. The process was also monitored by acoustic emission (AE), which indicates to be a promising and suitable technique to be used in this process. Compared to lapping, there is an additional advantage of a less contaminated workpiece surface with a shiny appearance.     

Method, algorithm and device for estimation of components above the harmonic frequency range up to 9 kHz

The paper presents a method of estimation of frequency groups with 200 Hz bandwidth in the frequency range from the 50th harmonic up to 9 kHz. The method consists of the application of a fast Fourier transform (FFT) for wavelet coefficients after input signal decomposition and partial synthesis for chosen frequency bands. It enables the computational complexity of the algorithm to be reduced and also attenuates influence of the fundamental component and low-frequency harmonics, as required by IEC Standard 61000-4-7. The particulars of this method are shown and analysis for a chosen wavelet family is provided. Further, the algorithm and its implementation in real device for power quality monitoring is presented. Finally, the results of measurements of two testing signals are shown. The required attenuation of fundamental component and required accuracy was obtained.     

A microcontroller-based variable voltage variable frequency sinusoidal power source with a novel PWM generation strategy

The present paper describes the development of a low cost, microcontroller-based variable voltage variable frequency sinusoidal power source, which is the demand of the day for various applications. The power source is developed using MOSFET H-bridge inverter and with a stand alone LCD display system. The design methodology proposes to utilize a novel concept of generating sinusoidal pulse width modulation signals for the driver circuit of the inverter. The system proposes to incorporate a ROM-based LUT within the power source itself for the sinusoidal signal generation with enhanced stability. This low cost, yet accurate power source has been successfully developed for wide range of voltage commands (30-80 V rms) and frequency commands (40-70 Hz), and their real-life performances in voltage wave generation were also found to be quite satisfactory.     

Multiple scattering effects of MeV electrons in very thick amorphous specimens

Multiple scattering has an important influence on the analysis of microns-thick specimens with MeV electrons. In this paper, we report on effects of multiple scattering of MeV electrons on electron transmission and imaging of tilted and thick amorphous film specimens by experiment and theoretical analysis. Electron transmission for microns-thick epoxy-resin and SiO₂ specimens calculated by the multiple elastic-scattering theory is in good agreement with measurements in the ultrahigh voltage electron microscope (ultra-HVEM) at Osaka University. Electron transmission and electron energy are then presented in an approximate power law. The bright-field ultra-HVEM images of gold particles on the top or bottom surfaces of 5 and 15 μm thick specimens further illustrate the effect of multiple scattering on image quality. The observed top‐bottom effect for the very thick specimens appears to be mainly caused by multiple elastic scattering. With increase in the accelerating voltage from 1 to 2 MV, image blurring, contrast, the signal-to-noise ratio, and the top‐bottom effect are improved because of reduction in the influence of multiple scattering. However, the effect of specimen thickness on image blurring is shown to be stronger than that of accelerating voltage. At the 2 MV accelerating voltage, the 100 nm gold particle can be imaged with less blurring of ∼4 nm when located at the bottom surface of a 15 μm thick epoxy-resin specimen.     

RF CMOS transceiver at 2.4 GHz in wearables for measuring the cardio-respiratory function

This paper presents a radio-frequency (RF) transceiver for operation in the 2.4 GHz ISM band. The RF CMOS transceiver can be supplied with only 1.8 V, and it was designed to establish wireless links for distances up to 10 m, for a maximum baud-rate of 250 Kbps with a Bit Error Probability less than 10⁻⁶. The transmitter can deliver a output power of 0 dBm with a consumption of only 11.2 mW, while the receiver has sensitivity of −60 dBm and consumes only 6.3 mW. The goal of RF CMOS transceiver is for co-integration with sensors in the same die using microsystems techniques. The target application of such microsystems is in wearables (e.g., in wireless electronic shirts) for measuring biomedical data of patients. The wireless electronic shirt (WES) measures the heart rate and the respiratory frequency, and at the same time it allows patients to maintain their mobility.     

Validation and generalization of a method for precise size measurements of metal nanoclusters on supports

We recently described a data analysis method for precise (∼0.1 Å random error in the mean for a 200 kV instrument with a 3 Å FWHM probe size) size measurements of small clusters of heavy metal atoms on supports as imaged in a scanning transmission electron microscope, including an experimental demonstration using clusters that were primarily triosmium or decaosmium. The method is intended for low signal-to-noise ratio images of radiation-sensitive samples. We now present a detailed analysis, including a generalization to address issues of particle anisotropy and biased orientation distributions. In the future, this analysis should enable extraction of shape as well as size information, up to the noise-defined limit of information present in the image. We also present results from an extensive series of simulations designed to determine the method's range of applicability and expected performance in realistic situations. The simulations reproduce the experiments quite accurately, enabling a correction of systematic errors so that only the ∼0.1 Å random error remains. The results are very stable over a wide range of parameters. We introduce a variation on the method with improved precision and stability relative to the original version, while also showing how simple diagnostics can test whether the results are reliable in any particular instance.     

Measurements of dimensional standards and etalons with feature size from tens of micrometres to millimetres by using sensor strengthened nanomeasuring machine

A laser focus sensor and a contact inductive sensor have been coupled to an ultra high precision positioning stage, referred to as a nanomeasuring machine (NMM), for measurements of dimensional standards with a large measurement volume of 25 mm × 25 mm × 5 mm. Control and measurement software have been designed and complemented. The measurement uncertainty of strengthened NMM has been analyzed and discussed. Groove depth and step height standards with feature heights of tens of micrometres to millimetres as well as aspherical surface etalons are calibrated by nanomeasuring machine. The paper also introduces a method for characterising the measured aspheric surface by least square fitting the measured data to a quadratic paraboloid function. The obtained quadratic coefficients are compared to that measured by a conventional coordinate measuring machine (CMM) and a stylus profiler, showing a good agreement.     

Measuring large 3D structures using four portable tracking laser interferometers

A new concept that allows measuring 1D–3D objects in the range of several centimeters to 5 m × 5 m × 5 m is presented. In general terms the concept can be seen as a task specific correction of geometrical errors of coordinate measuring machines (CMMs). The developed system comprises a commercial CMM, its measurement and its evaluation software and a set of at least four high accurate tracking laser interferometers. The CMM is simply used as a mover which allows to capture points on the surface of a measuring object. In parallel the tracking laser interferometers follow a retro-reflector located close to the stylus tip of the tactile probe of the CMM. Based on a multi-lateration algorithm 3D-positions are calculated from the measured interferometric distances. Finally, two sets of coordinates emerged, namely, one by the CMM and the second from the metrological frame of the tracking laser interferometers. The interferometrically measured positions are usually more precise than the positions measured by the CMM. This is due to the high accuracy of the interferometric system and also due to the fact that the measurement positions are taken in a manner which almost avoids Abbe errors. Because of that, the measurement positions of the CMM are substituted with the more accurate measurement points calculated from distance measurements of the tracking interferometers. The position coordinates thus obtained are used for the further computerized evaluations, which yield the geometric parameters of the object measured. First measurements under laboratory condition show very promising results. It has been demonstrated that the concept is suitable for the high precision calibration of large workpieces with small tolerances, for instance, for the calibration of large gears for the windmill industry.     

In-process out-of-roundness measurement probe for turned workpieces

A new in-process and non-contact probe is proposed to measure the diameter and the roundness of turned workpieces. The initial probe discussed in previous publications exhibited diameter measurements with good accuracy (uncertainty 5 μm over 100 mm). This paper discusses the implementation of roundness measurement into the initial probe and its performance. The principle of the roundness measurement is based on the relationship between the displacement and the light intensity. The probe delivers a maximum error of 0.5 μm with an uncertainty of 1 μm for roundness measurement over a range of 100 mm diameter.     

Accurate conductance measurements of a pinhole orifice using a constant-pressure flowmeter

A pinhole orifice with a known conductance can be used as a secondary flow standard. Commercially available laser-drilled pinhole orifices with diameters ranging from 1.0 μm to 50 μm can have molecular-flow conductances ranging from about 0.1 μL/s to 200 μL/s for N₂ at 23 °C. Gas flows of 10⁻¹¹–10⁻⁶ mol/s can easily be produced by applying an upstream pressure in the range of 1–10⁵ Pa. Accurate measurements of the orifice conductance as a function of pressure are required to use the pinhole orifice as a basis of a flowmeter. We use a constant-pressure flowmeter to make accurate measurements of the conductance of a 20 μm orifice as a function of pressure for gas flows of Ar and N₂ into vacuum. We present results of these conductance measurements for an orifice with a nominal diameter of 20 μm. The N₂ conductance of this orifice ranged from 30 μL/s to 60 μL/s over the range of pressures investigated, and was measured with an uncertainty of better than 0.2% (k = 2) for upstream pressures greater than 10 Pa.     

Development of high-precision micro-coordinate measuring machine: Multi-probe measurement system for measuring yaw and straightness motion error of XY linear stage

Today, with the development of microsystem technologies, demands for three-dimensional (3D) metrologies for microsystem components have increased. High-accuracy micro-coordinate measuring machines (micro-CMMs) have been developed to satisfy these demands. A high-precision micro-CMM (M-CMM) is currently under development at the National Metrology Institute of Japan in the National Institute of Advanced Industrial Science and Technology (AIST), in collaboration with the University of Tokyo. The moving volume of the M-CMM is 160 mm × 160 mm × 100 mm (XYZ), and our aim is to achieve 50-nm measurement uncertainty with a measuring volume of 30 mm × 30 mm × 10 mm (XYZ). The M-CMM configuration comprises three main parts: a cross XY-axis, a separate Z-axis, and a changeable probe unit. We have designed a multi-probe measurement system to evaluate the motion accuracy of each stage of the M-CMM. In the measurement system, one autocollimator measures the yaw error of the moving stage, while two laser interferometers simultaneously probe the surface of a reference bar mirror that is fixed on top of an XY linear stage. The straightness motion error and the reference bar mirror profile are reconstructed by the application of simultaneous linear equations and least-squares methods. In this paper, we have discussed the simulation results of the uncertainty value of the multi-probe measurement method using different intervals and standard deviations of the laser interferometers. We also conducted pre-experiments of the multi-probe measurement method for evaluating the motion errors of the XY linear stage based on a stepper motor system. The results from the pre-experiment verify that the multi-probe measurement method performs the yaw and straightness motion error measurement extremely well. Comparisons with the simulation results demonstrate that the multi-probe measurement method can also measure the reference bar mirror profile with a small standard deviation of 10 nm.     

Performance evaluation of a new taut wire system for straightness measurement of machine tools

This paper describes evaluation of a method of measuring the straightness of motion of machine tool axes using a taut wire and an optical sensor head mounted at the tool point location. In contrast to commonly used taut wire instruments, straightedges or laser-based methods, this solution combines low cost, simplicity of setup and automated data capture while achieving state of the art accuracy suitable for application on precision machine tools. A series of tests are discussed which examine the performance of the new sensing head and different wires which highlight the suitability of the taut wire properties as a straightness reference. Experimental results obtained on a production machine tool are provided with respect to the accuracy and repeatability of both the proposed taut wire system and a laser interferometer operated under the same conditions. The reference errors of wires made of different materials are compared and the wire catenary is separated from the measurement results. The uncertainty budget for taut wire and laser systems is presented and expanded uncertainty of 4 μm obtained for both. During the experiment, the method showed excellent repeatability with two standard deviations of 1.5 μm over a measuring range of 1.5 m; this performance matches that of a commercial laser interferometer-based straightness reference to within 0.1 μm.