武居 昌宏

A sensitive frequency f margin SFM has been determined for quantification of aggregated interstitial protein concentrations Фprot by frequency difference electrical impedance tomography fd-EIT. Impedances of increasing Фprot of albumin-globulin mixtures in phantoms were measured and changes in protein's adjacent f point conductivity Δσadj and loss factor Δε''adj plotted against f to determine a Фprot SFM fsen where σadj and ε''adj change significantly with Фprot. Results show that the Δσadj and Δε''adj dropped rapidly with increase in f up to f = 10 kHz then gradually to f = 100 kHz. The σ and ε” were only sensitive to Фprot as f increased from 1 to 10 kHz. For fd-EIT, optimum reference frequency fref was set at 100 kHz. At fsen = 1 kHz against fref, fd-EIT reconstructed σ due to 30% increase in Фprot with area ratio error ARE = 4.1% and a position error PE = 0.1 [-].

In situ measurement of hindered settling function Hϕ as a function of particle volume fraction ϕ in a decanter centrifuge has been proposed by periodic segmentation technique in wireless electrical resistance detector (psWERD). The processes to calculate Hϕ has three steps which are (1) segmentation of measured resistance R(z,t) in three settling periods; (2) elimination of the screw conveyor's (SC's) adverse effect; (3) calculation of ϕ which is important to determine the in situ hindered settling velocity uhinins and calculation of the proposed uhinfit from the proposed Hϕ. In the 1st step, R(z,t) are segmented based on the phases of liquid L, screw S, and particle P under three settling periods which are pre settling (pre), transient settling (tran), and post settling (post). In the 2nd step, the segmented R(z,t) is categorized by fourier transfrom (FT) based on the frequency of the liquid fL, screw fS, and liquid-particle fLP phases with a focus on eliminating SC's adverse effect which causes fluctuating R(z,t). In the 3rd step, the ϕz,t is obtained by applying the effective medium theory (EMT) based on the conductivity of each phase which are liquid σ¯L, particle σP, and slurry σLPz,t. Each conductivity is calculated based on the average liquid resistance R¯Lz, the static particle resistance RP under closed-pack particle volume fraction ϕcp, and the slurry (liquid-particle) resistance RLPz,t from the 2nd step. Afterward, the uhinins is obtained from the distribution of ϕ which refers to the length parameter in the settling radius rset. Hence, the uhinins is calculated by time t needed for particle to settle from ϕ0 to ϕcp in tran. The proposed Hϕ is developed by considering the influence of ϕcp and the increasing distribution of ϕ due to the particle settling which is presented by fitting parameters of k and p. Take into account the importance of single particle settling in Stokes settling velocity uSt, the proposed uhinfit is determined by calculating the uSt and fitting parameters in the Hϕ to fit the uhinins. To evaluate the psWERD, a decanter centrifuge was used in the industrial scale experiment by appliying three operational parameters which are types of SC, centrifugal forces G, and the differential speeds ω. Two types of SC which are SC1 and SC2 were used to investigate the effect of G to the in situ Hϕ under constant ω. While SC2 was used to investigate the effect of ω to the insitu Hϕ under contant G. The in situ measurement is conducted in three measurement points z which represents the particle settling condition at different locations. In order to verify the experiment results, simulation on electrical measurement in the boundary of particle sensitivity area APSA of psWERD and on particle settling behavior in centrifugal fields are done by Multiphysic software. As a result, the psWERD is successful in determining the best fitting parameters for the in situ Hϕ with good average root mean square error 〈RMSE¯〉≤10-3. The in situ Hϕ also has a good agreement to the previous work of Hϕ determined in decanter centrifuges with the similar operational condition. Finally, the Hϕ shows the potential for evaluating the in situ separation process in decanter centrifuges under specific operational conditions.

The use of 3D cell culture for tissue engineering and regenerative medicine applications often challenges conventional biochemical and optical assays. Impedance‐based cellular assays have shown their potential to retrieve dielectric parameters pertaining to cell behavior such as viability, proliferation, and differentiation for 2D adherent cell culture. Herein, simultaneous 3D impedance imaging and viability measurements of multiple large (>2 mm) 3D cell cultures embedded in collagen gels are demonstrated. The method is facilitated by low‐resistance 3D printed scaffolds that can hold a 3D cell–gel system throughout cell culture while being transparent to impedance imaging. It is shown in silico and in vitro that frequency‐difference electrical impedance tomography (fd‐EIT) can nondestructively and in a label‐free way differentiate a variety of cell concentrations with a single miniature sensor in real time. This study paves the way toward the development of EIT imaging for the quantitative and noninvasive evaluation of tissue engineering products.

Dynamic fields visualization method of carbon-black (CB) volume fraction ΦCB distribution in Lithium-ion battery (LIB) cathode slurry has been proposed based on electrical resistance tomography (ERT) during the manufacturing process. The proposed method consists of an impedance analyzer, a switching circuit, and ΦCB distribution imaging algorism, archiving to the measurement speed of 5 frames per second. In experiments, ΦCB distribution was visualized by the proposed method in lab-scale LIB cathode manufacturing equipment. To qualitatively evaluate the ΦCB distribution images, those images are compared with scanning electron microscope (SEM) images. This comparison shows that the ΦCB distribution images are qualitatively consistent with SEM images. In addition, in order to quantitatively evaluate the proposed method, the accuracy of reconstructed ΦCB distribution is evaluated by electromagnetic field simulations. As a result, the root mean square errors RMSE between the known ΦCB distribution and that obtained by the proposed method was less than 0.56%.

Albumin diffusivity coefficient DaI in imitated porous structure of interstitial space has been estimated by means of the integration of albumin diffusion model (ADM) to electrical impedance tomography (EIT) (iADM-EIT) under five different porosity φ conditions (from φ1 = 0.922 to φ5 = 0.990) for transport phenomena quantification. The iADM-EIT was conducted by applying an iterative curve-fitting between spatio-temporal albumin concentration CaI derived from ADM and spatio-temporal distribution of conductivity difference Δσ reconstructed by EIT. The essential point of the iADM-EIT is the quantification of experimental CIa from Δσ by establishing a constitutive relationship among CIex a, Δσ, and φ. ADM is developed based on Fick's second law implemented in Krogh tissue cylinder. EIT is performed to image the Δσ caused by increase of CIa due to albumin diffusion phenomenon from a capillary to the imitated porous structure. The imitated porous structure is manufactured with agarose gel in a dynamic phantom including a capillary. As a result, the relative albumin diffusivity coefficient (D0a: free diffusivity of albumin coefficient) is increased with the increase of φ in the range from 0.271 to 0.694, which are correspondent to the literature data with percent average relative error δ = 6.83 ± 2.72%.

In-vivoviscoelastic properties have been estimated in human subcutaneous adipose tissue (SAT) by integration of poroviscoelastic-mass transport model (pve-MTM) into wearable electrical impedance tomography (w-EIT) under the influence of external compressive pressure -P. Thepve-MTM predicts the ion concentration distributioncmod(t)by coupling the poroviscoelastic and mass transport model to describe the hydrodynamics, rheology, and transport phenomena inside SAT. Thew-EIT measures the time-difference conductivity distribution∆γ(t)in SAT resulted from the ion transport. Based on the integration, the two viscoelastic properties which are viscoelastic shear modulus of SAT Gvand relaxation time of SAT τvare estimated by applying an iterative curve-fitting between the normalized average ion concentration distribution〈čmod〉(t)predicted from pve-MTM and the experimental normalized average ion concentration distribution〈čexp〉(t)derived fromw-EIT. Thein-vivoexperiments were conducted by applying external compressive pressure -Pon human calf boundary to induce interstitial fluid flow and ion movement in SAT. As a result, the value of Gvwas range from 4.9-6.3 kPa and the value of τvwas range from 27.50-38.5 s with the value of average goodness-of-fit curve fitting R2> 0.76. These value of Gvand τvwere compared to the human and animal tissue from the literature in order to verify this method. The results frompve-MTM provide evidence that Gvand τvplays a role in the predicted value of č_mod.

IEEE Plural long short term memory (pLSTM) applying to a multiple voltage-current (mVC) system has been proposed in order to estimate the void fraction α. accurately in gas-liquid flows. The pLSTM consists of two LSTMs, one for flow regime identification (fri-LSTM) and the other for void fraction estimation (vfe-LSTM). The fri-LSTM identifies a flow regime q from current vectors i, corresponding to gas distribution, measured by mVC system. Based on the identification result and i, the customized vfe-LSTM to each q estimates α. For training, i are experimentally measured at 36 points of the true void fraction α, which is calculated by the drift flux model. On the other hand, i for test data are measured under 12 points of α. Two parameters of each LSTM, one is sequence length S representing time dependence length considered within the LSTM and the other is the number of LSTM blocks M related to the estimation performance, are optimized so that accurate void fraction estimation is achieved. As a result, pLSTM applying to mVC system achieves a 100% accuracy of flow regime identification and less ±0.00034 standard error of void fraction estimation in liquid single-phase flow, bubble flow, slug flow, and churn flow. Accurate estimation is caused by the fact that pLSTM can consider the time dependence of gas-liquid flows suitable for each flow regime and neglect the effect of the flow regime on i.

© 1964-2012 IEEE. Low-frequency impedance-based (LFI) cell discrimination as a novel non-destructive and non-invasive cell discrimination is proposed. LFI cell discrimination discriminates the cell type by considering an ion transport model in cell suspension. Ion transport model in cell suspension is constructed on the basis of Fick's laws of diffusion in the extracellular region under ion permeability P which represents the characteristics of cell type. P is achieved using the ion transport model equation through an iterative curve fitting to an ion concentration in extracellular region obtained from low-frequency impedance which is assumed to be linearly related to the ion concentration in extracellular region. In experiment, the electrical impedance spectra from the frequency of 200 kHz to 2.0 MHz are measured over time during producing ions from intracellular region to extracellular one in cell suspension using an impedance analyzer and an interdigitated array electrode system. As a target cell type, two different cell types based on Medical Research Council 5 (MRC-5), which are different in intracellular component are used. The curve fitting is performed for the low-frequency impedance at 200 kHz at which impedance reflects the ion concentration in extracellular region in order to obtain P of each cell type. As a result, each cell type has its own P. The proposed LFI cell discrimination successfully discriminates the cell type.

© 2020 IEEE. A portable Electrical Impedance Tomography (EIT) device has been developed for online thrombus detection in extracorporeal-circulation equipment. For the portable EIT device, circuits of multiplexer module are designed to expend channels, pipeline processing mechanism is introduced to increase processing speed, and data acquisition rate reaches 50 Frames Per Second (FPS) and the online tomography rate reaches 40 FPS with 8-electrode sensor. To test the characteristics of the proposed EIT device, a series of experiments are conducted. Firstly, small sensors with different size and plastic phantoms are used to test the static properties of the device. Testing results show that the quality of the reconstructed images is related to the diameter of sensor, and Image Correlation (IC) reaches 0.75 when diameter of sensor is 30 mm. Secondly, swine blood is used for making thrombus to verify the EIT device's image reconstruction ability of thrombus in stationary conditions instead of human blood. Experiments show that the reconstructed image error is 8.07% when diameter of the sensor is 10 mm, and it reduces to 1.49% when diameter is 30 mm. Finally, experiments are conducted to measure the position of flowing thrombus. Euclidean distance between voltage data is used to judge the occurrence of thrombus. Experimental results indicate that thrombus is clearly distinguished from the background solution in fluids. As a conclusion, the proposed EIT device is of great significance for online thrombus detection in extracorporeal-circulation system.

© 2020 IEEE. This paper has proposed a new dielectric properties extraction method of cell's complex permittivity ϵ *cell even in cell solutions from the measured impedance Z*sol, exp by GHz electrical impedance spectroscopy (EIS) in the frequency range from 10 MHz to 3 GHz. This new extraction method is composed of the electrical impedance measurement of cell solutions and dispersed medium and the dielectric properties calculation based on a combination of plane wave and transmission line theories. By comparing with ϵ*cell, BH obtained by Bruggeman-Hanai equation, this new method is proved to extract the complex permittivity of cells ϵ*cell in cell solutions successfully from the experimental impedances of yeast cell solutions Z*sol, exp and dispersed medium Z*dis, exp by GHz EIS with the relative error less than 10% in the frequency range from 10 MHz to 3 GHz. Moreover, the conductivity of cell σcell among different concentrations obtained by this method shows the smaller discrepancy than that obtained by Bruggeman-Hanai equation in the frequency range from 1 GHz to 3 GHz. The dielectric properties ϵ*cell and ϵ*cell, BH are brought into a simulation model, respectively. The simulated impedance Z*sol, sim shows a better agreement with the experimental impedance Z*sol, exp compared with the simulation impedance Z*sol, sim, BH which means the dielectric properties ϵ*cell obtained by this new method is accurate for the future research of cell's dielectric properties in the GHz frequency range.

© 2021, The Author(s). Three-dimensional ion and particle concentrations under hydrodynamic focusing in a Y-shaped square microchannel are numerically simulated to clarify the decrease of the ion concentration along the flow direction within the focused particle stream. The simulation model is theoretically governed by the laminar flow and advection–diffusion equations. The governing equations are solved by the finite volume method. The ion and particle concentration distributions at five cross sections after the confluence of the branch channels are analyzed in 30 cases in which the sheath to sample flow rate ratio Qsh/Qsam and the Reynolds number Re are varied as parameters. The results show that the decrease of the cross-sectional average ion concentration along the flow direction within the particle stream c¯ i is described by the diffusion length during the residence time with a characteristic velocity scale. In addition, the deformation of the particle stream due to inertial effects is described by a scaled Reynolds number that is a function of the flow rate ratio. The simulated particle stream thicknesses are validated by theory and a simple experiment. This paper reveals the relationship between the ion and particle concentrations and the dimensionless parameters for hydrodynamic focusing in the Y-shaped square microchannel under typical conditions.

© 2020 The Author(s) We propose a noise elimination electrical impedance spectroscopy (neEIS) system for single cell identification whose characteristics are cell-free clamp structure and cell-position independent calibration. The function of the cell-free clamp structure is to enable a single cell to be freely located into neEIS system. The cell-position independent calibration consists of three steps; impedance measurement, electrode cell constant calculation, and single cell dielectric properties estimation. The cell-position independent calibration enables elimination the influence of noise associated with ions as well as electrical double layer during the measurement process. We demonstrate an application of neEIS system to discriminate three types of MRC-5 human lung fibroblasts; wild type (WT), GFP-fused histone (HT) modification, and GFP transfected (GFPT) MRC-5 cells suspended in a sucrose medium. To further evaluate the neEIS system, we simulated the electrical potential distribution and root means square error of single cell dielectric properties numerically. As a result, we obtained electric potential distribution which clearly characterized the internal change of single cell components. Moreover, we determined that the neEIS system is capable of accurate single cell identification after noises elimination with less than 1.05% average root means square error. Taken together, these results demonstrate that the proposed neEIS system has the potential to improve the performance of biosensors. Thus, this study will bring a new insight into the development of a biosensor system for high accuracy single cell identification as well as inspire the development of a diagnostic device for early fetal lung diseases based on the neEIS system.

© 2001-2012 IEEE. A novel real-time dynamic imaging method has been proposed for flexible boundary sensors in wearable electrical impedance tomography (wearable EIT). The novel method has three stages; 1) estimation of flexible boundary shape Ω (t) at time t , 2) computations of clustered Jacobian matrix J( Ω (t)) using parallel cloud computing (PCC) and 3) reconstruction of conductivity distribution images σ (Ω (t)) based on Ω (t). Initially, Ω (t) is estimated based on a shape factor nq of Lame curve which is calculated from axial circumference cq and axial length mq. The cq and mq are calculated by stretch detectors dd and angle detectors θ q integrated in the wearable sensor. J( Ω (t) ) is then clustered into several processors p in PCC based on potential fields produced by the current injected to the e -th electrode and the measured voltage from m -th adjacent electrode patterns. Finally, σ (Ω (t)) is reconstructed by the Gauss-Newton method based on J( Ω (t) ) and measured voltage V. The performance of the proposed imaging method is qualitatively and quantitatively evaluated using three different shaped phantoms. From the results, the boundary shape is well estimated with boundary error be = 5.78\% compared with the true boundary shape. The clustered Jacobian matrix computation J( Ω (t) ) improves the performance speed sp by 20.17 times compared with the standard Jacobian matrix computation. It also provides a more accurate Jacobian matrix with a Jacobian error je = 2.92% compared with the true Jacobian matrix. The σ (Ω (t)) provides more accurate reconstructed images with relatively low rmse = 0.0023[-].

© 2020 The Society of Powder Technology Japan This paper presents a novel method to predict the gas layer thickness δ′ in an improved cluster renewal model (ICRM) to calculate the heat transfer coefficient h′c for a rolling circulating fluidized bed (RCFB). Eulerian-Eulerian two-fluid model (TFM) with kinetic theory of granular flow is used to perform a numerical simulation. After comparing the pressure gradient −△p/△z′ and the simulated heat transfer coefficient between multiphase and the wall hgs with previously published experiment data, the correctness and reliability of the simulation are able to be verified. In conclusion, firstly, the variation of h′c calculated from δ′ in the ICRM is almost the same with hgs in the case that the RCFB undergoes the rolling motion. In order to quantitatively evaluate the proposed novel method, an error percentage α between h′c calculated from δ′ and hgs is 2.043% which is less than 5%. This certified that the novel method to predict δ′ in the ICRM has higher accuracy to calculate h′c. Secondly, h′c calculated from δ′ is mainly influenced by rolling amplitude Θ rather than by rolling period T. Specifically, with the increase of Θ, amplitudes of Ts are decreased, which is caused by the increased heat transfer and the decreased δ′ between cluster and wall. The decreased amplitudes of Ts are able to increase heat transfer efficiency, which eventually increases h′c. Thirdly, in the case that normalized rolling period t/T is changed from 0 to 0.5, higher h′c calculated from δ′ in Region Ⅰ results from the large local cross-sectional particle volume fraction clocal in Region Ⅰ with a smaller δ′, while lower h′c calculated from δ′ in Region III results from the smaller clocal in Region III with a larger δ′. Therefore, it is concluded that h′c calculated from δ′ is able to well predict the bed-to-wall heat transfer coefficient of the RCFB even if the rolling motion is considered.

© 2020 The Society of Powder Technology Japan Electrical capacitance tomography with airflow injection system (ECT-AIS) has been developed for controlling particle distribution in pneumatic conveyance in order to maintain homogeneous downstream particle distribution εndot+τ with a delay time τ even under inhomogeneous upstream particle distribution εnupt. ECT-AIS is composed of two ECT sensors for monitoring εnupt and for evaluating εndot+τ after injecting airflow. The airflow is injected to the conveyance pipe by activating a solenoid valve of airflow injection system (AIS) to control the homogeneous εndot+τ in the case that the spatial standard deviation of permittivity distribution at the upstream ECT sensor εSDupt which is calculated from εnupt and the spatial mean permittivity 〈εnup〉t is greater than the threshold value δ. With this developed ECT-AIS, three different experiments are performed under different particle loading ratios (ϕ = 0.25, 0.50 and 0.75) with air flow rate Qa = 0.75 kg/s, 0.50 kg/s and 0.25 kg/s. As εnupt is homogeneous, εndot+τ is also homogeneous. While εnupt was inhomogeneous, εndot+τ was homogeneously distributed due to airflow injection. To evaluate the homogeneity of εndot+τ, the spatial mean permittivity 〈εnup〉t in upstream sensor is compared with 〈εndo〉t+τ in downstream sensor and the two results were evaluated with the measured pressures pnupt and pndot. As a results, εSDdot+τ is less than or equal to δ so that 〈εndo〉t+τ is homogeneous after airflow injection. Based on Darcy–Weisbach equation, as the particles are homogeneous, the pressure is lower than that in inhomogeneous distribution. According to the relationship between mean permittivity and pressure, εndot+τ is successfully controlled in homogeneous conditions by ECT-AIS.

© 2020 Author(s). There is a strong need for a non-invasive measurement technique that is capable of accurately identifying the physiological condition change or heterogeneity of subcutaneous adipose tissue (SAT) by localizing the abnormalities within the compartment. This paper aims to investigate the feasibility of Electrical Impedance Tomography (EIT) to assess the interstitial fluid in subcutaneous adipose tissue as an enhancement method of bioelectrical impedance spectroscopy (BIS). Here, we demonstrate the preliminary result of EIT with a wearable 16 electrodes sensor. The image-based reference EIT with fat weighted threshold method is proposed. In order to evaluate the performance of our novel method, a physiological swelling experiment is conducted, and Multi-Frequency Bioelectrical Impedance Analysis (MFBIA) is also applied as a comparison with EIT results. The experimental results showed that the proposed method was able to distinguish the physiological swelling condition and effectively to remove the unexpected background noise. Furthermore, the conductivity variation in the subcutaneous layer had a good correlation with extracellular water volume change from MFBIA data; the correlation coefficient R2 = 0.927. It is concluded that the proposed method provides a significant prospect for SAT assessment.

© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Optimal serum protein concentrations are vital for normal body functioning. Affordable while accurate protein quantification methods with minimum processing requirements are needed for diagnosis of related diseases. The standard automated chemistry analyzer is limited by high installation and maintenance costs. This study proposes the use of electrical impedimetric spectroscopy (EIS) as an alternative to current methods. Its practical applicability was tested using albumin and γ-globulin or their miscellanea in three different media; water, serum and tissue-mimicking phantoms at 25 °C. Impedance measurements were taken between frequency f=0.10 MHz to 300 MHz by an impedance analyzer. A Cole-Cole analysis was used to elucidate the stepwise variations in the dielectric parameters of the protein medium so as to obtain empirical dielectric parameter-protein concentration relationships and their correlation coefficients R2. From the results, linear relationships between parameters and protein concentrations with high correlation coefficients over R2=0.90 were observed. Resistance to charge transfer Rct and characteristic frequency fc were significantly altered by changing protein concentrations as compared to bulk solution resistance Rs, relaxation time constant τ and shape factor α. The relationships developed would aid in monitoring changes in body fluid protein concentrations by EIS.

© 2020 Elsevier B.V. Particle volume flow rate QPLUG· in plug flow through a cross section of horizontal pipe has been accurately measured by a combination of dual electrical capacitance tomography sensor and plug flow shape model (dECT-PFSM). The plug flow shape model divides the trapezoidal shape of the plug flow into three flow regions which are Tip, Filling, and Tail regions. The plug flow volume VPLUG is estimated by velocity and length which are measured in each region by the normalized permittivity signal changes obtained from the dECT images under the plug flow in the trapezoidal shape. The path time difference of the plug flow ΔtPLUG is also measured. The total volume flow rate of the plug flow is subsequently obtained from the sum of the plug flow volume of the three regions divided by ΔtPLUG. Consequently, the volume flow rate of the plug flow obtained by dECT-PFSM QECT, PFSM· is compared with that of high-speed camera (HSC) as reference and conventional cross-correlation (CC) method. The absolute error Eabs of the proposed method is less than that of the CC method. The dECT-PFSM method is, therefore an affordable noninvasive technique for accurate determination of the volume flow rate of the plug flow.

© 2020 IOP Publishing Ltd. This study investigates the in situ sludge thickness of polymers in a real-scale horizontal decanter centrifuge using the optimized particle resistance normalization (OPRN) technique. The sludge thickness of poly(methyl methacrylate) (PMMA) in an aqueous sodium chloride (NaCl) carrier fluid was observed as a function of the normalized particle resistance of a wireless electrical resistance detector. The measured resistance of the continuous phase during the centrifugation is set as the reference and normalized following its dominant frequency by Fourier transform. Here, the OPRN limits the particle resistance using the normalization function based on the closed-packing condition (i.e. Krieger 1972 Adv. Colloid Interface Sci. 3 111-36; Phillips et al 1992 Phys. Fluids A 4 30-40; and Rao et al 2002 Int. J. Numer. Methods Fluids. 39 465-83) in the particle sensitivity area (PSA). The normalized value is then plotted in the fitting equation using a nonlinear generalized reduced gradient. The PSA is solved by a simulation study on electrostatics and by static experiments. Two different centrifugation parameters of feed rates and two centrifugal forces at four different measurement points were considered to observe the sludge thickness distribution as a function of operational time. As a result, the in situ sludge thickness is described in the nonlinear fit plot equation with a coefficient score to explain the separation phenomenon inside the decanter centrifuge. The plot agrees well with the experimental data with a high degree of coefficient of determination.

© The Author(s) 2019. This paper investigated the particle dispersion behaviours of Lithium-ion battery (LIB) slurry by using electrical impedance spectra-tomography (EIST) method from the perspective of experiment and simulation. In the experiment, an EIST system composed of Field—Programmable Gate Array (FPGA), multi-plexer, switch circuit and 8-electrode sensor is developed to measure the frequency response of LIB slurry under two different conditions, which are rotation speed n=0rpm with rotation time t=0min and n=100rpm with t=6min. In the simulation, four different geometry structure models, which are (a) Carbon Black (CB) linear formation, (b) CB aggregation, (c) CB & LiCoO2 aggregation and (d) network dispersion, are established. Six frequencies, which are f=1 kHz, f=10 kHz, f=50 kHz, f=100 kHz, f=250 kHz and f=500 kHz, are used for the reconstructed conductivity images of LIB slurry in both the experiment and the simulation. The numerical simulation is used to verify the correctness of the experiment results. After combining the experiment and the simulation, it is concluded that the agglomeration behaviours of CB and LiCoO2 particles appear within LIB slurry in the case of n=0rpm with t=0min, while CB path and part LiCoO2 particles coated by CB particles appear in the case of n=100rpm with t=6min. Moreover, high frequencies are suitable to distinguish high conductive CB components from LIB slurry. Furthermore, the developed EIST system has the capability of monitoring particle dispersion behaviours in LIB slurry, which has the potential to be used for the on-line measurement of LIB slurry in order to improve the performance of LIB.

© Japanese Society of Biorheology 2020. The influence of fibrinogen concentration on blood dielectric properties has been analyzed by GHz electrical impedance spectroscopy (EIS). The complex impedances of native blood and blood with various fibrinogen concentrations Z*blood,exp were measured by a coaxial sensor in the frequency range from 1 MHz to 3 GHz. The complex permittivity of native blood and blood with various fibrinogen concentrations ε*blood were extracted from the Z*blood,exp by equivalent circuit model based on the transmission line theory. The reactance Xblood,native and resistance Rsblood,native of native blood have a peak called characteristic frequency fc at around 300 MHz. At the time t = 0 min just after fibrinogen addition, the relative blood permittivity εblood decreases, conductivities σblood increases and fc shifts to higher frequency with increase of fibrinogen concentrations cfib in plasma. With increment of time, from t = 0 min to t = 12 min, εblood decreases while σblood slightly decreases to time because red blood cell (RBC) aggregation reaction. By comparing the εblood,native of native blood and blood with various cfib, the fibrinogen dissolved in plasma rises the blood permittivity. However, fibrinogen is unable to rise the blood permittivity unlimitedly because of RBC aggregation reaction.

© 1964-2012 IEEE. Enhancement of positive dielectrophoresis (pDEP) particle trapping by a co-occurring fluid flow under an ac electric field in an electrode-multilayered microfluidic device is investigated by three-dimensional particle-fluid flow simulations. The particle motion near one cross section of the microfluidic device is simulated under a zero flow condition by the Eulerian-Lagrangian method incorporating the ac electrothermal effect, thermal buoyancy, and dielectrophoresis. The mean trapping rate under the steady state Rm is evaluated from the simulated number of trapped particles Ntrap for 54 cases with four parameters: electrode excitation pattern, medium conductivity σ, applied voltage φe, and the real part of the Clausius-Mossotti factor Re[K(ω)]. The simulated pDEP velocity in the upper part of the flow channel is validated by an experiment using cell suspension and is fitted so that the non-dimensional velocity error is within 15% of a typical velocity of pDEP. The mean trapping rate Rm is greatly increased by the fluid flow only in the high conductivity and high voltage cases. Regardless of the electrode excitation pattern, Rm increased almost proportionally to the inflow rate into the capture region, where the pDEP force is effective. From a fitted equation of the results, the increase of Rm when Re[K(ω)] = 0.1 to 0.5 is found to be about 20% to 30% of the number of particles transported into the capture regions. The results quantify the enhancement of pDEP trapping by the fluid flow occurring under practical conditions in the device.

© 2001-2012 IEEE. The normalization equation with two correction parameters {beta } and {gamma } is proposed to estimate the void fraction of liquid-gas flow under the condition of unstable liquid conductivity using a multi-electrode voltage-current (me-VC) system. The variation of electrical current value due to change in liquid conductivity of liquid phase is corrected using parameter {beta }. While {gamma } is the gradient correction parameter, which corrects the different variation rate of normalized electrical current affected by liquid conductivity and the void fraction {alpha } in liquid-gas flow. A lookup table for {beta } and {gamma } is created based on the normalized electrical current obtained at four liquid conductivity and six void fraction conditions. From the experimental results, the proposed normalization equation with {beta } and {gamma } shows better performance in estimating void fraction than conventional normalization equation when the conductivity of liquid in liquid-gas flow is unstable. Through the results, it is found that the proposed normalization equation successfully measures the void fraction {alpha } within a 5% error rate.

© 2001-2012 IEEE. Void fraction in gas-liquid flow has been estimated using the artificial neural network (ANN) with electrical current response (ECR) from a voltage-current (VC) system, which measures electrical currents through the combination with eight electrodes attached around a pipe for gas-liquid flow. The ANN model for ECR with the number of neurons {N} =3136 has the lowest relative error and absolute error, respectively, in estimating void fraction of gas-liquid flow, among five different numbers of neurons ( {N} =392, 784, 1568, 3136 , and 6272) on a hidden layer of the ANN model for ECR. With regard to the change in total loss during the training process, the ANN model for ECR with {N=3136} shows good convergence as 28\times 10^{-4} for void fraction estimation in gas-liquid flow compared to other ANN models with different numbers of neurons {N}. In this paper, electrical currents measured by the VC system in the static experiment with eight void fraction conditions are used to optimize the ANN model for ECR in order to estimate void fraction of gas-liquid flow. In the gas-liquid flow with seven void fraction conditions, the optimized ANN model for ECR is applied for void fraction estimation in order that the estimation performance according to the number of neurons on the hidden layer is evaluated.

© 2019 IOP Publishing Ltd. A weighted parameter vector χ norm based on extracellular fluid resistance in the Cole impedance model is hereby proposed in order to compensate for the volatile-distributed current. The volatile-distributed current due to variance in the unknown contact impedance in an electrical impedance tomography (EIT) sensor distorts the ideality of the frequency-dependent behavior of the object of interest, leading to inaccuracy in the reconstructed images. The sources of variance in the unknown contact impedance include the use of electrodes with inconsistent impedance values, electrochemical reaction or the improper attachment of electrodes to the object of interest. χ norm represents the current pathway lengths at zero frequency which reflects the volatile-distributed current, and it is used to determine the source of the measured impedance. The source of the unknown contact impedance can be the background object in the normal physiological condition, an inclusion object in an abnormal physiological condition or systematic error. The new reconstruction methods are derived from the frequency-difference EIT (fd-EIT) and the weighted-frequency-difference EIT (wfd-EIT) using χ norm. The new reconstruction methods are frequency-difference electrical impedance spectro-tomography (fd-EIST) and weighted-frequency-difference electrical impedance spectro-tomography (wfd-EIST). The performance of fd-EIST and wfd-EIST was evaluated by experimental and simulation studies using biomaterials with frequency measurements from f = 500 Hz to f = 100 kHz and the results were compared with those from fd-EIT and wfd-EIT. The results showed that the use of χ norm reduces the root mean square error, position error, ringing and shape deformation. It also increases the ideality of the frequency-dependent behavior, either for the inclusions or the background objects at different frequencies.

IEEE A particle-fluid two-phase flow under alternating current (AC) electrokinetics was numerically simulated to investigate the three-dimensional (3D) particle motion in a complex electric field of a high conductivity medium generated by an electrode-multilayered microfluidic device. The simulation model coupling thermal-fluid-electrical and dispersed particle problems incorporates three AC electrokinetics (ACEK) phenomena: the AC electrothermal effect (ACET), thermal buoyancy (TB) and dielectrophoresis (DEP). The electrode-multilayered microfluidic device was fabricated with forty electrodes exposed at the flow channel sidewalls in five cross sections. The governing equations of the simulation model are solved by the Eulerian-Lagrangian method with finite volume discretization. Fluid flow simulations in three cases with or without consideration of ACET and TB are performed to clarify the contributions of these phenomena. The fluid flow is found to be composed of short-range vortices due to ACET and long-range circulation due to TB based on the features of the electrode-multilayered microfluidic device. The 3D particle trajectory influenced by the fluid flow is compared with four values of the real part of the Clausius-Mossotti (CM) factor to evaluate the DEP phenomenon. The simulation model is validated by experiments using a cell suspension. The pattern of cell trajectories in the upper part of the flow channel measured by Particle Tracking Velocimetry agrees with the simulated pattern. By comparison of the simulation and experiment, it is found that the cells moving straight away from the electrode on the focal plane are decelerated within the region of 60 μm from the electrode by positive-DEP with Re[K(ω)] = 0.10-0.14. Furthermore, the 3D DEP-effective region and the ACET and TB dominant region for the cells is predicted by evaluating the slip velocity due to DEP force with Re[K(ω)] = 0.13. Consequently, the flow mechanism and dominant region of each ACEK phenomenon in the device are clarified from the 3D simulation validated by the experiments.

A micro electrical impedance tomography (μEIT) system is developed to visualize cells concentration distribution in microchannel flow. Due to the complexity of electrical properties of the μEIT system in micro-scale measurement, simulation and experiments are conducted to find the optimal conditions of the image reconstruction process. In the simulation, three image reconstruction algorithms which are generalized vector sampled pattern matching (GVSPM), iterative tikhonov regularization (TK) and projected landweber iteration (PLW) are estimated, GVSPM is found to be the optimal algorithm for image reconstruction in the present study due to its higher image correlation IC = 0.84 and lower image error IE = 0.43. In the experiment, yeast cells and purified water are employed as two-phase flow to measure the cells sedimentation in the microchannel at a range of frequencies with GVSPM, TK and PLW, respectively. The optimal frequency for the μEIT system is found as f = 1 MHz due to its higher measurement sensitivity. GVSPM is found as the optimal image reconstruction algorithm because of its low voltage error UE = 0.582 and simpler image reconstruction without regularization factor. Finally, images of cells sedimentation are reconstructed with GVSPM in three cross-sections in microchannel flow at f = 1 MHz. The reconstructed images show that concentration of cells sedimentation from the upstream Z1 to downstream z5 is decreased gradually along the flow direction in the microchannel.

© 2001-2012 IEEE. Image reconstruction is a key problem for electrical resistance tomography (ERT). Because of the soft-field nature and the ill-posed problem in solving inverse problem, traditional image reconstruction methods cannot achieve high accuracy and the process is usually time consuming. Since deep learning is good at mapping complicated nonlinear function, a deep learning method based on convolutional neural network (CNN) is proposed for image reconstruction of ERT. To establish the database, 41122 samples were generated with numerical simulations. 10-fold cross validation was used to divide all samples into training set and validation set. The network structure was based on LeNet, and refined by applying dropout layer and moving average. After 346 training epochs, the image correlation coefficient (ICC) on validation set was 0.95. When white Gaussian noise with a signal-To-noise ratio of 30, 40, and 50 were added to validation set, the ICC was 0.79, 0.89, and 0.93, respectively, which proved the anti-noise capability of the network. The reconstruction results on samples which have more inclusions, different conductivity, and other shapes explained the network has good generalization ability. Furthermore, experimental data from a 16-electrode industrial ERT system was used to compare the accuracy of the proposed model with some typical reconstruction methods. Results show that the proposed CNN method has better reconstruction results than LBP, Tikhonov, and Landweber.

© 2013 IEEE. An empirical model is proposed to detect the living cell fraction Φ in a multi-mixed cell solution by micro electrical impedance spectroscopy (EIS) as Φ = -1.46 ψ0 + 1.97. The living cell indicator ψ0 is defined by a quotient of the extrema in the impedance imaginary parts of the detected cell solution's medium, Zextmed , and referenced Zextmedref. The theoretical effectiveness of the model is examined by an electrochemical simulation. In addition, the sensor size versatility is discussed by a comparison experiment that reveals that the sensor size has little effect on the detection result. To support real-time detection, Zextmed and Zextmedref are replaced by the impedance of the cell solution, Zextm, and Zextmref. The versatility of real-time detection is discussed by a medium similarity coefficient η (f) that is defined to explain the effect of replacement. The results reveal the feasibility of the replacement as η > 95 % in the injected current frequency range of ψ 0 by micro EIS.

© 2018 We have developed a non-invasive rapid and real-time red blood cell (RBC) hemolysis detection method which is a more accurate for point of care testing of hemolysis in various medical settings. An eight-parameter equivalent circuit is employed to quantify the release of hemoglobin (Hb) and the cytoplasm from RBC into the blood plasma. RBC hemolysis is induced by adding different volume fractions of distilled water into the blood. The cytoplasm released following RBC hemolysis is estimated from the experimental values. A strong relationship between RBC hemolysis and change in the electrical characteristics of blood has been demonstrated. The cytoplasm resistance (Rc) shows a linear relationship with the Hb. This relationship between Rc and Hb is described by the equation Rc = 0.2203Hb + 2.4775, with a correlation coefficient of 0.9905.

Characteristics of electrical parameters (characteristic frequency fc, shape factor α resistance at zero frequency R0 and resistance at infinite frequency R∞) in swine flowing blood have been clarified under various flow rates by multiple-frequency electrical impedance measurement to obtain the physical interpretations for the influence of blood flow rate. In order to quantitatively evaluate the experimental results, the conventional Hanai mixture formula for static colloids has been modified from the viewpoint of blood flow-dependent factors which are RBC (red blood cell) orientation, RBC deformation and EDL (electrical double layer) thickness around RBCs. The experimental results are compared with the theoretical evaluations by the modified Hanai mixture formula. This formula is applicable to evaluate the characteristics of electrical parameters of flowing blood since the small errors for fc, α R0 and R∞ between the experimental and theoretical results which are only efc = 3.4%, eα = 19.3%, eR0 = 3.1% and eR1 = 1.7%. Blood flow-dependent factors (RBC orientation, RBC deformation, and EDL thickness) are clarified to be accountable for the variation of electrical parameters of flowing blood.]