Nondestructive Detection of Magnetic Contaminant in Aluminum Casting Using Thin Film Magnetic Sensor

The thin film magneto-impedance sensor is useful for detecting a magnetic material nondestructively. The sensor made by single layer uniaxial amorphous thin film has a tolerance against surface normal magnetic field because of its demagnetizing force in the thickness direction. Our previous study proposed the sensitive driving circuit using 400 MHz high frequency current running through the sensor to detect the logarithmic amplifier. We also confirmed the sensitivity of the sensor within 0.3 T static normal magnetic field, which resulted in detection of 5 × 10−8 T of 5 Hz signal. This paper proposes a nondestructive inspection system for how detecting a contaminant of small tool steel chipping in aluminum casting specimen would be carried out. Three channel array sensors installed in the 30 mT static field detecting area were fabricated and experimentally showed a detection of low remanence magnetic contaminant in a bulk aluminum casing specimen.

Electronics and Control

This chapter discusses electronics and computer interfaces for STM and AFM. For STM, the detection of the minute tunneling current is of paramount importance. Thus, the basic concepts and analysis of the current amplifier, or more accurately speaking, the transimpedence amplifier, is discussed. It includes the typical circuits and an analysis of the gain, noise, frequency response, microphone effect due to the coaxial cable, and the logarithmic amplifier to make the distance dependence of the output signal linear. the feedback system is then discussed, including a typical circuit, as well as the analyses of the steady-state response and the transient response. Finally, the architecture of the computer interface system with the algorithm of automatic approaching is discussed.

LOGARITHMIC AMPLIFIERS FOR SOFTWARE HARDWARE MAGNETIC TRACKING SYSTEMS

The work deals with the problem of signal conversion in magnetic tracking devices. Magnetic tracking technology is based on computing the spatial position of an object being tracked upon measuring reference magnetic fields in low-frequency electromagnetic radiation spectrum. Magnetic tracking devices are key components of navigation sensors for virtual and augmented reality. It has been shown that the main problem one faces when developing sensory devices for magnetic tracking is the fact that signals should be measured in a wide measurement range. We have analyzed possible ways to solve the stated problem by digital and combined methods. The latter have proven to be more efficient. They consist in signal amplification due to analog compression, which is performed by logarithmic amplifiers whose negative feedback circuits contain components with non-linear volt-ampere characteristics (typically, diodes or bipo- lar transistors are used). It has been shown that the parameters of logarithmic signal compression can be controlled by modified circuits with auxiliary resistance dividers. The resistance dividers scale the logarithmic volt-ampere characteristics of emitter p-n junctions of bipolar n-p-n and p-n-p transistors. A substantial advantage of circuits with resistance dividers is that they provide the possibility to expand the range of the output voltage of logarithmic amplifiers and optimize the transition between the linear and logarithmic amplification regions. The work presents the results of simulation and experimental investigations into a logarithmic amplifier for a magnetic tracking system. Simulation was carried out using SPICE (Simulation Program with Integrated Circuit Emphasis) models. We applied an integrated approach,which provides collections of transient characteristics of logarithmic amplifiers at different sets of the parameters of resistance dividers. The simulation results have been verified using our own software- firmware magnetic tracking tools – Magnetic Tracking System Integrated Development Environment. The signal converter was built upon a programmable system-on-chip PSoC 5LP by Cypress Semiconductor.

150 α6 Integrin for evaluating sperm quality in bulls with different capacities of invitro embryo production

The α6 integrin, an adhesion molecule, is expressed on bovine sperm, but major questions about the role of integrins in sperm-oocyte fusion remain unsolved. In this work, we show the results of characterisation of sperm α6 integrin from 4 bulls with different capacities of invitro embryo production using flow cytometric analysis. The bull capacities judged by the rate of blastocyst formation after invitro embryo production with semen from 5 ejaculates per animal were 44.3, 17.1, 13.2, and 15.0% for bulls 1, 2, 3, and 4, respectively (P<0.05). For flow cytometric analysis, surface expression of α6 integrin was evaluated using a fluorescence-activated cell sorter (FACScan, Coulter Electronics) using a 520-nm excitation from an argon laser at 150 mW for excitation. Frozen-thawed sperm were centrifuged at 700×g for 10min and washed once in warm phosphate buffered saline (PBS). Briefly, the spermatozoa (5×105 cells per sample) were resuspended in 100μL of PBS containing 1% bovine serum albumin. After washing 3 times, the live cells were incubated at room temperature for 1h with 100μL (1:500) of α6 monoclonal antibody (Chemicon) in PBS (0.1M, pH 7.4) with 1% bovine serum albumin. After washing three times, the cells were incubated at 4°C for 1h in the dark with the fluorescein isothiocyanate-conjugated F(ab)2 fragment of affinity isolated goat anti-mouse antibody (Invitrogen). The cells were washed three times, resuspended in 100μL of PBS, and analysed. For each sample, 10 000 cells were recorded at a flow rate of 200-300 cells s−1 using forward scatter (cell size) and side angle of light scatter (cell density), the first using a logarithmic amplifier and the second using a linear amplifier. The fluorescence data were collected using the logarithmic amplifier. The percentage of positive cells and the mean fluorescence channel on a 1023-channel scale were calculated using Epics Profile II software (Epics II Software). To define the forward and side-scatter regions corresponding to sperm, binding of fluorescein isothiocyanate-conjugated Pisum sativum agglutinin to the acrosome was used for setting the bitmap on the dot plot. Initially, the percentage of spermatozoa stained with α6 antibody was calculated on a per-individual basis. Subsequently, the mean±standard deviation was calculated for each group. The Mann-Whitney U test was used to compare the differences in the expression of α6 between groups. Expression of α6 integrin was higher in bull 1 (control) than in bulls with low capacities of invitro embryo production. The spermatozoa from bull 1 was distributed in a single broad peak with a mean fluorescence intensity of 36.16±4.17%. The increased distance of the fluorescence intensity in bull 1 compared with the weak fluorescence peaks in the others bulls reflects the increased width and distance of the population distribution. In conclusion, α6 integrin may be used as a biomarker to evaluate sperm quality. This study was supported by FAPESP grants 2010/01077-9, 2011/18085-7, and 2016/00976-6.

High-CMRR Low-Noise Fully Integrated Front-End for EEG Acquisition Systems

We present in this paper a fully integrated low-noise high common-mode rejection ratio (CMRR) logarithmic programmable gain amplifier (LPGA) and chopped LPGA circuits for EEG acquisition systems. The proposed LPGA is based on a rail-to-rail true logarithmic amplifier (TLA) stage. The high CMRR achieved in this work is a result of cascading three amplification stages to construct the LPGA in addition to the lower common-mode gain of the proposed logarithmic amplification topology. In addition, the 1 / f noise and the inherent DC offset voltage of the input transistors are reduced using a chopper stabilization technique. The CMOS 180 nm standard technology is used to implement the circuits. Experimental results for the integrated LPGA show a CMRR of 140 dB, a differential gain of 37 dB, an input-referred noise of 0.754 μ Vrms, a 189 μ W power consumption from 1.8 V power supply and occupies an active area of 0.4 mm 2 .

Magneto-Impedance Sensor Driven by 400 MHz Logarithmic Amplifier

A thin-film magnetic field sensor is useful for detecting foreign matters and nanoparticles included in industrial and medical products. It can detect a small piece of tool steel chipping or breakage inside the products nondestructively. An inspection of all items in the manufacturing process is desirable for the smart manufacturing system. This report provides an impressive candidate for realizing this target. A thin-film magneto-impedance sensor has an extremely high sensitivity, especially, it is driven by alternatiing current (AC) around 500 MHz. For driving the sensor in such high frequency, a special circuit is needed for detecting an impedance variation of the sensor. In this paper, a logarithmic amplifier for detecting a signal level of 400 MHz output of the sensor is proposed. The logarithmic amplifier is almost 5 mm × 5 mm size small IC-chip which is widely used in wireless devices such as cell phones for detecting high-frequency signal level. The merit of the amplifier is that it can translate hundreds of MHz signal to a direct current (DC) voltage signal which is proportional to the radio frequency (RF)signal by only one IC-chip, so that the combination of a chip Voltage Controlled Oscillator (VCO), a magneto-impedance (MI) sensor and the logarithmic amplifier can compose a simple sensor driving circuit.

A Wideband Extended-Dynamic-Range Successive Detection Logarithmic Amplifier Based on 0.15 μm GaAs pHEMT Technology

This paper puts forward an extended-dynamic-range successive detection logarithmic amplifier (SDLA) for [Formula: see text]-band (18–26.5[Formula: see text]GHz) applications. A novel single-transistor power detection unit (PDU) is used instead of a conventional rectifier to effectively improve the dynamic range–bandwidth product of the amplifier. Circuit analysis and mathematical modeling are performed for the proposed PDU and the SDLA, respectively. Transistor level design is carried out for the whole circuit using 0.15[Formula: see text][Formula: see text]m GaAs pseudomorphic high electron mobility transistor (pHEMT) technology. The SDLA presents a wide dynamic range of 75[Formula: see text]dB with a [Formula: see text] 1.5[Formula: see text]dB logarithmic error, over the entire band of interest, and consumes 340[Formula: see text]mW from [Formula: see text] 2.5[Formula: see text]V and –0.8[Formula: see text]V power supplies. All requirements are verified in post-layout simulation using ADS software. Thermal simulation and statistical yield analysis are performed to ensure the robustness of the proposed architecture.