Human Body Impedance Research Articles

Enhancing Electric Field Distribution in the Pancreas for Improved TTFields Therapy: A Computational Modeling Investigation.

Tumor treating fields (TTFields) therapy has shown effectiveness in glioblastoma treatment and holds potential for other cancers. However, its application in pancreatic cancer and the distribution of electric fields in pancreas remain unexplored. This study aims to investigate the electric field distributions in pancreatic regions using different array configurations for TTFields therapy. Computational modelling was employed to simulate electric field distributions, and quantitative analysis was conducted. Human body impedance measurements were used to optimize the electric properties of the model. Various array configurations were examined to assess their impact on the electric field distributions. The study revealed that well-positioned arrays, specifically the combination of 20-piece transducer arrays in anterior-posterior orientation and 13-piece transducer arrays in left-right orientation, consistently achieved electric fields exceeding the 1V/cm threshold in over 99.4% of the pancreas. Even with a reduced number of transducers (13 pieces for both orientations), sufficient electric field coverage was achieved, exceeding the threshold in over 92.9% of the pancreas. Additionally, different array placements within the same orientation were explored to address clinical challenges such as skin rash and patient anatomical variations. This research lays the groundwork for understanding TTFields distribution within the abdomen, offering insights into optimizing array configurations for improved electric field delivery. The findings have the potential to guide practical designs of TTFields devices, enhance treatment efficacy, and improve patient outcomes. These results offer promises of advancing TTFields therapy for pancreatic cancer towards clinical applications, and potentially enhancing treatment efficacy and patient outcomes.

Ultrasound‐Driven Highly Stable Implantable Triboelectric Nanogenerator with Human‐Tissue Acoustic Impedance‐Matched Polyether Ether Ketone

AbstractImplantable electrical neurostimulators offer a promising avenue for treating neurological disorders. However, their dependency on a finite battery life limits their long‐term utility. Emerging transcutaneous ultrasound‐driven triboelectric nanogenerator (TENG) techniques provide solutions for converting external ultrasound waves into internal electricity. This study proposes an implantable ultrasound‐driven TENG (IU‐TENG) using polyether ether ketone (PEEK) for its exceptional stability inside a human body and acoustic impedance compatibility with human tissues. This IU‐TENG remarkably surpasses traditional titanium‐based encapsulation, resulting in a 99.94% efficiency in ultrasound transmission. In addition, PEEK contains numerous electron‐donating functional groups, making it suitable for TENG applications, particularly as a positive triboelectric layer. The device exhibits robust voltage outputs, reaching up to 11.50 and 8.75 V in water and in vivo, respectively, under body‐safe ultrasound intensities. Moreover, its ability to sustain a stable electrical output for over 300 min emphasizes the durability and mechanical resilience of PEEK. In vivo mouse models and ex vivo porcine tissue trials demonstrate the effectiveness of the IU‐TENG in nerve stimulation, showing its potential in medical treatments, enhancing the functionality and longevity of implantable medical devices.

Multipoint ECG Signal Extraction on Palms and Figures for Human Identification System

The ECG signal contain vital information for cardiac disease which is one of main cause of catastrophic mortality. In conventional technique, the signals are extracted through different points located on the limbs and surface of the chest. The biological impedance of human body eliminates any practical means of making fake copies of the relevant physiological traits. Moreover, this method needs the complex data acquisition system and apparatus as well as inconvenience way of acquisition of signal at the chest. Hence, there is a demand to find out the promising alternative technique to extract the ECG signals in more convenient way with high accuracy. In this paper, the real-time ECG monitor has been developed to extract the signals from the multipoint on the hands and fingers. Placement of the electrodes are done based on the acupressure point on palms and fingers. A total of 120 volunteers were investigated to develop the ECG database as the development dataset. This work uses the template matching algorithm and distance classification method to analyze and to find the best similarities between the developed dataset of ECG biometric signals to improve the identification rate. In order to lessen the noise that was recorded with the ECG signals, signal averaging was used to create ECG databases and templates. The recognition rate rose to 98% accuracy on the development dataset when the prescreening procedure was introduced to create a combined system model. ECG biometric model was created by combining the two models and using the development dataset's results. The algorithm was applied on the entire developed ECG dataset and 96% of accuracy rate was achieved in identification.

Nonisolated Three-Phase Current DC-Link Buck–Boost EV Charger With Virtual Output Midpoint Grounding and Ground Current Control

Non-isolated three-phase AC/DC converter concepts facilitate more compact and more efficient realizations of future EV chargers. However, without the galvanic isolation and/or high common-mode (CM) impedance provided by an isolation transformer, non-isolated chargers must employ other means to suppress CM leakage currents to ground sufficiently and to prevent nuisance tripping of mandatory residual current devices (RCDs). Typically, the required EMI filters reduce high-frequency (HF) CM leakage currents to uncritical values. However, low-frequency CM voltages, e.g., generated by third-harmonic injection, may drive significant LF CM currents through the parasitic capacitances of the DC output (including the battery pack) to protective earth (PE). Therefore, considering a non-isolated three-phase buck-boost current DC-link PFC rectifier system that consists of a buck-type current-source rectifier (CSR) stage and a three-level boost-type DC/DC-stage, this paper first proposes a virtual grounding control (VGC) of the DC output voltage midpoint. VGC employs the DC/DC-stage to compensate the LF (third-harmonic) CM voltage inherently generated by the CSR-stage, and thus controls the LF CM voltage between the DC output midpoint and PE to zero. This enables further a direct connection of the DC output midpoint to PE, where an additionally proposed ground current control (GCC) ensures near-zero LF CM leakage current. The proposed concepts are verified with a 10kW hardware demonstrator (power density of 6.4 kW/dm3 or 107.5 W/in3, full-load peak efficiency of 98.5%) considering TT (Terra-Terra) and TN (Terra-Neutral) grounding systems. With a direct connection of the DC output midpoint to PE, GCC limits the LF CM leakage current to < 6mA RMS, i.e., significantly below typical RCD trip levels, and, using the human-body impedance model according to UL 2202, achieves a test voltage of 110mV that is clearly below the most stringent limit (250 mV) of the standard.

Study the Changes of Bioelectrical Skin Impedance of Human body Associated with Different Physiological Parameters

Bioelectrical Impedance Plethysmography, in other hand Galvanic Skin Response (GSR) of living system specially for human body is deal with great importance as it changes with different physiological parameters and help to predict the different kind of disease like diabetes mellitus, human mental stress etc. This changing pattern also varies with the human ages and life styles. In this study we have collected the GSR values of two groups of people one is young generation under 20-25 years old and group is middle age under 40-50 years old. The GSR values were collected by using Grove-GSR Sensor with Arduino Uno. The individual’s data was analysed in Mat-lab and the statistical parameters like standard deviation and mean of the extracted datasets was calculated respectively and documented. The statistical parameters from the changing pattern of GSR clearly indicate that this changing is fully associated with the different physiological parameters and different ages which indirectly deal with great significance for pre identification of human diseases.

A New Model for Human Body Impedance

The impedance of the human body is strongly voltage-dependent, and exhibits substantial variation among individuals. We introduce a new statistical model that separates body impedance into three terms (internal tissue, skin, and contact impedances in series). Advantages over simpler models include a physically plausible monotonicity with respect to voltage and the ability to simulate the impedance characteristics of individuals.

Intention Recognition in Physical Human-Robot Interaction Based on Radial Basis Function Neural Network

To solve synchronization movement problem in human-robot haptic collaboration, the robot is often required to recognize intention of the cooperator. In this paper, a method based on radial basis function neural network (RBFNN) model is presented to identify the motion intention of collaborator. Here, the human intention is defined as the desired velocity in human limb model, of which the estimation is obtained in real time based on interaction force and the contact point movement characteristics (current position and velocity of the robot) by the trained RBFNN model. To obtain training samples, adaptive impedance control method is used to control the robot during the data acquisition process, and then the data matching is executed due to the phase delay of the impedance function. The advantage of proposed intention estimation method according to the system real-time status is that the model overcomes the shortcoming of difficult estimating the human body impedance parameters. The experimental results show that this proposed method improves the synchronization of human-robot collaboration and reduces the force of the collaborator.

Non-iterative algorithm for computation of the prospective permissible touch voltage according to EN 50522

The prospective permissible touch voltage computation algorithm can be found in the international standards and technical specifications. By combining values of the total human body impedance and values of the permissible body current, extracted from tables and figures, the relevant permissible touch voltage as a function of the fault duration is obtained using an iterative process. In this paper, a simple and robust non-iterative algorithm for computation of the prospective permissible touch voltage according to EN 50522 for chosen fault duration is presented. In proposed algorithm, computation of the prospective permissible touch voltage is reduced to linear combination of permissible touch voltage for a current path hand to hand and permissible body current.For chosen fault duration, permissible touch voltage for a current path hand to hand and permissible body current are computed using piecewise cubic Hermite interpolation and given sampled values of these functions and sampled values of their derivatives with respect to fault duration.

Dynamics of frequency dependences of parameters of electric impedance of a person during dry fasting

Introduction The article considers the possibility of further development of the method of analysis of the parameters of electrical impedance to determine the current functional state of a person in various conditions of his life, in particular during the dry fasting. The aim of the study was the dispersion properties investigation of the amplitude and phase parameters of human body impedance in the extended frequency band during the weekly one and half day dry fasting. Methods. Measurement of electrical impedance parameters was performed weekly during half a year on one person before, during and after a day and a half fasting . Broadband three-frequency measurement technique is used. The possibility of analyzing the dispersion characteristics of a human body using the Cole hologram is considered. Results and discussion. It is established that in the process of dry fasting there is a change of all parameters of impedance. The most pronounced changes in the parameters of electrical impedance are observed by the definition of the module and the active component at a frequency of 100 kHz, the phase at frequencies 20 and 500 kHz, the reactive component at a frequency of 20 kHz. Conclusion. Changes in the dispersion properties of the human body impedance are noticeable in all parameters especially in phase and reactive resistance. According to the research results an interpretation of changes in the functional state of a person during fasting was made.

Realization and Evaluation of the Device for Measuring the Impedance of Human Body for Detecting the Respiratory and Heart Rate

The idea of a device for measuring the impedance of human body with the target of monitoring the respiratory and heart rate is proposed in this paper. Hardware realization of the proposed idea is described with the illustration of the custom designed printed circuit board. Preparation of electrode shirts with various electrode placement configurations is introduced. Series of experimental measurements in the cases of dynamic bioimpedance reference and single human subject are described and results shown to evaluate the custom made device. The excitation frequencies in the range of 2 MHz–20 MHz are utilized in the cases of large foil and textile electrodes to focus on the use of the capacitive connection to the object – constituting the novelty of the current paper. The results are analysed concerning the dependency of the visual availability of the interesting signal of breathing and heart rate of the material and the placement of the electrodes. Availability of breathing is found to be evident in all of the experimented cases. The heart rate is found to be challenging because of the presence of high frequency noise.DOI: http://dx.doi.org/10.5755/j01.eie.23.3.18330

Fractional-order circuit models of the human body impedance for compliance tests against contact currents

Compliance tests against contact currents presently require the usage of equivalent circuit networks aimed to reproduce the human body impedance in the frequency range 0–110MHz. The IEC 60990 standard specifies an equivalent network that is valid up to 1MHz, while a recent work from the authors has extended the validity of the IEC network up to 110MHz. However, a number of 11 integer-order lumped elements was employed in the latter case. In this study, an equivalent network based on fractional-order circuit models is proposed in order to reduce the number of elements needed to fit the human body impedance. Moreover, the fitting of the mixed curve defined as the lowest impedance between the IEC network and the extended one is for the first time considered to provide a more protective compliance network in the whole frequency range.

Prediction of posture-dependent tremor by the calculation of the endpoint compliance.

This paper proposes to use the analysis of human mechanical impedance to predict spatial behavior of tremor. Traditional studies have revealed that the variability in force is proportional to the mean level of force generated, which is described as signal dependent noise. The variability in force sometimes generates unintentional and uncontrollable rhythmic muscle movements, called tremor. Tremor appears most commonly on arms and hands due to not only a symptom of a neurological disorder, but also when we tighten our muscles. This study hypothesizes that the posture-dependent tremor at the hand is affected by the mechanical impedance of the arm, which is represented as the endpoint compliance ellipsoid. To verify this hypothesis, we measured the trajectory of the endpoint of the arm by human experiments, and compared the results with the endpoint compliance ellipsoid computationally obtained. The human experiment where the oscillations at the hand are measured revealed that the simulation results well correspond with the human experiments. This suggests that the posture-dependent motion noise is affected by the mechanical impedance of human body.

직류환경에서 인체에 흐르는 감전전류 분석

Recently, DC distribution systems have become a hot issue because of the increase in digital loads and DC generation systems according to the expansion of renewable energy technologies. To obtain the practical usage of DC electricity, safety should be guaranteed. The main concerns for safety are twofold: one side is human protection against electric shocks, and the other is facility protection from short faults. Effects of current on human beings and livestock (IEC 60479) defines a human body impedance model in electric shock conditions that consists of resistive components and capacitive components. Although the human body impedance model properly works in AC electricity, it does not well match with the electric shock behavior in DC electricity. In this study, the contradiction of the human body impedance model defined by IEC 60479 in case of DC electricity is shown through experiments for the human body. From the analysis of experimental results, a novel unified human body impedance model in electric shock conditions is proposed. This model consists of resistive components, capacitive components, and an inductance component. The proposed human impedance model matches well for AC and DC electricity environments in simulation and experiment.

Compact Wide Frequency Range Fractional-Order Models of Human Body Impedance against Contact Currents

Three circuit models using constant phase elements are investigated to represent the human body impedance against contact currents from 40 Hz to 110 MHz. The parameters required to represent the impedance are determined using a nonlinear least squares fitting (NLSF) applied to the averaged human body impedance dataset. The three fractional-order models with 4, 6, and 7 parameters are compared to an already existing integer-order, 11-parameter model. Simulations of the fractional-order models impedance are presented and discussed along with their limitations.

New equivalent-electrical circuit model and a practical measurement method for human body impedance

Human body impedance analysis is an effective tool to extract electrical information from tissues in the human body. This paper presents a new measurement method of impedance using armpit electrode and a new equivalent circuit model for the human body. The lowest impedance was measured by using an LCR meter and six electrodes including armpit electrodes. The electrical equivalent circuit model for the cell consists of resistance R and capacitance C. The R represents electrical resistance of the liquid of the inside and outside of the cell, and the C represents high frequency conductance of the cell membrane. We propose an equivalent circuit model which consists of five parallel high frequency-passing CR circuits. The proposed equivalent circuit represents alpha distribution in the impedance measured at a lower frequency range due to ion current of the outside of the cell, and beta distribution at a high frequency range due to the cell membrane and the liquid inside cell. The calculated values by using the proposed equivalent circuit model were consistent with the measured values for the human body impedance.

신발의 전기저항 측정에 관한 연구

The occurrence of the ventricular fibrillation is directly dependent on the magnitude and duration of the current. The current which flows through the human body is proportional to the touch voltage applied across the body and is in inverse proportion to the impedances in the circuit. The circuit impedances consist of human body impedance, line impedance, equipment impedance, earth terminal impedance and impedance of shoes which a person put on. The impedance of shoes greatly affect the severity of the electric accidents. The human body impedances relevant to the contact areas, contact conditions, current paths and touch voltages are already determined in the IEC 60479-1. However, the impedance of shoes is ignored or substituted by a simple value because of the absence of the sufficient data. For example, the impedance of shoes plus ground contact resistance is postulated to be 1,000 Ω in the IEC 61200-612. In IEEE 80, the shoe resistance plus ground contact resistance is assumed to be bare foot with ρ/4b Ω. In this paper, we measured and analyzed the impedance of shoes with respect to conditions such as applied weight, environment variables and voltages. The results showed that the impedance of shoes is dependent on environment variables regardless of the types of shoes. Most of shoes showed the correlation with the applied force, whereas a few shoes showed characteristics related to the applied voltage. In terms of severity of electric shock, one thirds of test samples indicated to be dangerous in saltwater conditions.

Method for estimating probabilistic models of touch currents and impedance of human body relying on the effects of electric shock

Abstract The article provides a theoretical basis for a method allowing to calculate probability of effects of electric shock, as well as a method for determining probabilistic characteristics of random touch current values and of human body impedance in a person who suffered from specific effects of electric shock. Results of example calculations are presented, including probabilities of occurrence of sensory symptoms, exceeding the letgo threshold, and development of ventricular fibrillation, as well as probabilistic characteristics of random touch current values and of impedance of human body in people who experienced specific effects of electric shock.

Experimental and numerical helicopter pilot characterization for aeroelastic rotorcraft–pilot coupling analysis

Pilot–vehicle interaction represents a critical aspect of aircraft design. Very low-frequency, voluntary although unintentional interaction has been extensively investigated in fixed and rotary wing aeromechanics. Higher frequency, involuntary and thus passive interaction received similar attention in fixed wing aeromechanics, but not as much for rotary wing. The results of an experimental campaign for the characterization of the passive behaviour of rotorcraft pilots' biomechanics are presented. A flight simulator has been used to excite human subjects. The accelerations of their limbs and the motion induced by the vibrations of the limbs in the control inceptors have been recorded. The vertical, longitudinal and lateral directions have been independently excited, while measuring the motion of the arm directly involved in the control inceptor mostly affected by motion in each direction, namely the left and the right arms for the collective and the cyclic sticks, respectively. The frequency domain response has been evaluated; resulting noteworthy behaviour is discussed, addressing its relevance in modelling the passive behaviour of pilots within the bioaeroservoelastic rotorcraft analysis. The measurements of human body impedance, under realistic cockpit motion, are used to identify the direct transfer functions between the motion of the seat and the controls inadvertently fed back into the rotorcraft.

전원설비에 의한 공간조건별 전위분포 사례 연구

In this paper, potential distribution analysis through the six kinds of case studies examined in the environmental conditions change within a limited space, by the power supply system installed. To interpret the potential distribution using electromagnetic field analysis program and the parameters were state of the ground, the outer wall of the configuration state and the presence of human potential distribution was simulated. Potential distribution analysis, the size of nominal voltage, depending on the impedance of human body to be determined on the impact of surprise decision, but if equipped with appropriate protective equipment can be protected from lightning have been confirmed.

Assessment of Human Body Impedance for Safety Requirements Against Contact Currents for Frequencies up to 110 MHz

This paper deals with contact currents that may occur when the human body is in contact with two electrodes at different electrical potentials, e.g., an electrical/electronic device and the floor. Actually, any device must comply not only with electromagnetic compatibility and safety requirements, but also with specific electromagnetic field exposure recommendations in order to prevent health hazards for the occupational and general public population. Since the contact currents depend on the applied voltage and on the human body impedance, this last parameter has been measured for several configurations in a broadband frequency range, from 40 Hz to 110 MHz. From the measurement results, a new equivalent circuit of the human body impedance is derived by using a vector-fitting procedure. This equivalent circuit is very easy and can be adopted for compliance tests against contact currents.