Electrical Properties Of Biological Tissues Research Articles

Using the stm32f407vg microcontroller to study the amplitude-frequency characteristics of biological tissues

The electrical properties of biological tissues of a plant origin are studied using the microcontroller STM32f407vg. The formulation of the problem of identifying informative signs of the viability of biological tissues when using the method of impedance measurement is given. It is shown that since currently in medical diagnostic practice there is no instrument base that would allow in an operational setting to diagnose the ability of biological tissue to self-heal after injury and damage as a result of thermal exposure, a gunshot wound or prolonged compression, the development of methods and means of instrumental diagnostics in this area of knowledge is an important modern task.
 The results of experimental measurements of impedance characteristics in the frequency range of 20 Hz – 2.0 MHz are presented. The frequency dependences of the stress modulus of a biological tissue of a plant origin are analyzed in its intact state, as well as after exposure of samples of a biological tissue in a freezer.
 A comparative analysis of the obtained frequency dependences is carried out. A significant difference between the frequency dependences of the stress modulus on a biological tissue and the frequency dependence of the stress modulus on an isotonic solution is shown. The idea was proposed that the degree of difference in the frequency distribution of the impedance module of the biological tissue from the impedance module of the isotonic solution can serve as a criterion for assessing the degree of damage to the biological tissue.

Microwave-Based Dielectric Properties as an Electrophysiological Biomarker: Future Perspectives

Electrophysiology is the study of the electrical properties of biological tissues, which involves the movement of ions across cell membranes. The analysis of the movement of electrical charges through the body has a wide range of biomedical applications, such as diagnosing and planning treatment in cardiovascular, nervous systems, muscular, and gastrointestinal disorders. The dielectric properties of biological tissues change according to the water content in the tissue and are measured as permittivity and conductivity relative to the frequency of the electrical field. This principle has been applied in diagnostics and therapeutics using microwave energysuch as imaging and ablation, etc. This review article summarizes the potential use of measuring dielectric properties using microwave imaging and how it can augment electrophysiological studies in medicine.

Biomedical microwave-induced thermoacoustic imaging

Microwave thermoacoustic imaging (MTAI) is an exciting imaging technique rooted from the underlying principle of exploiting the distinct electrical properties of biological tissues. By using short-pulsed microwaves as a stimulation source and their interaction with the human body, MTAI has paved the way for revolutionary advancements in medical imaging. When microwaves are absorbed by polar molecules and ions within the tissues, an ingenious thermoelastic effect gives rise to ultrasound waves. These ultrasound waves, brimming with invaluable pathological and physiological insights, propagate outward, carrying the essence of the composition and functionality of biological tissue. Through a meticulous collection of ultrasound signals from all directions surrounding the tissue, it becomes possible to reconstruct intricate internal structures and visualize the tissue's functional dynamics. The MTAI excels in non-invasiveness, capable of delving several centimeters beneath the surface with a microscopic resolution on the order of micrometers. The magic lies in converting microwave energy into ultrasound waves, entering into the hidden depths of tissues without causing harm. This groundbreaking imaging modality unlocks a realm of possibilities for acquiring profound insights into the intricate structures and functionality of deep-seated tissues. Furthermore, the inherent polarization characteristics of microwaves empower MTAI to capture additional dimensions of information, unraveling the intricate polarization properties and illuminating a richer understanding of the tissue's complexity. The great potential of MTAI extends far and wide within the medicine field. It has made remarkable achievements in non-invasive imaging of brain structures, screening breast tumors, visualizing human arthritis, and detecting liver fat content. These accomplishments have laid a solid foundation, firmly establishing MTAI as a trailblazing medical imaging technique. The present study offers a comprehensive and in-depth exploration of the physical principles underpinning MTAI, the sophisticated system devices involved, and the recent groundbreaking research breakthroughs. Moreover, it delves into the exciting prospects and challenges that lie ahead in the future development of MTAI. As the technology continues to progress by leaps and bounds, MTAI is ready to break down barriers, and usher in a new era of unmatched imaging quality and performance. This, in turn, will open the floodgates for transformative innovations and applications in medical diagnosis and treatment. The anticipation is palpable as MTAI strives to make substantial contributions to the ever-developing medical imaging field, bestowing upon humanity more accurate, reliable, and life-enhancing diagnostic capabilities.

Determination of intracellular electrical parameters in bioelectrical impedance analysis

Creating a frequency characteristic curve for bioelectrical impedance analysis involves analyzing electrical resistance (impedance) values at different frequencies. This curve is used to evaluate the electrical properties of biological tissues or fluids. In the article, the impedance of the intracellular environment was evaluated and frequency dependence was established based on the electrical circuit model of the biological system. Xc = f(f), Z = f(f), φ= f(f) tgδ= f(f), dependencies were created for different frequency values of the intracellular environment in the Matlab program through a series-connected RC circuit. Regression and general statistical analyzes were performed. The most appropriate frequency range was determined to evaluate the impedance of the intracellular environment. The correlation relationship of electrical and dielectric parameters of the intracellular environment was also taken into account. Purpose: The main goal of the research is the selection of the optimal frequency range for bioimpedance analysis. In particular, the selection of the most optimal frequency was carried out in the assessment of intracellular electrical activity. The frequency range is determined depending on the electrical and dielectric parameters of the cell. Materials and Methods: Using the Matlab program, the equivalent circuit model of the cell was assembled. Frequency dependence of electrical and dielectric parameters characterizing intracellular processes was performed by model-based measurements. Conclusion: According to the obtained value, regression and general statistical analyzes were performed for the dependencies Xc=f(f), Z=f(f), φ=f(f), tgδ=f(f). Based on analysis of variance (Analysis of Variance-ANOVA) of the output variables, statistical parameters were determined for each dependency.

Studying of biological tissue electrical resistance

Studying of biological tissue electrical resistance. / N. Tavadze, O. Ketiladze, I. Kantaria, M. Chikhladze. / Nano Studies. – 2020. – # 20. – pp. 137-140. – geo. A mathematical analysis of the RCR-equivalent scheme often used in practice to model the electrical properties of biological tissues is given. There is studied disperssion of the Achilles heel muscle’s impedance, form of which in good approximation fits the theoretical curve. Fig. 7, Ref. 5.

Segmental Bioimpedance Analysis as a Predictor of Injury and Performance Status in Professional Basketball Players: A New Application Potential?

Bioelectrical impedance vector analysis (BIVA) is a technique used for the assessment of body composition based on the electrical properties of biological tissues and for evaluating variations related to hydration and nutrition status changes. The present study aimed to investigate the possibility of predicting performance status and injuries using segmental BIVA analysis. Data were collected from 14 professional male athletes aged between 20 and 39 years of Caucasian and Afro-American ethnicity belonging to the US Victoria Libertas Pallacanestro Pesaro team in the Italian Serie A basketball championship. From an analysis of training injuries, the data highlight a possible positive link between the number of training injuries and upper hemisoma reactance (XCEmsSup) (t = 2.881, p = 0.007), an inverse relationship between training injury duration and higher right lower limb reactance (XCLegDx) (t = −4.213, p < 0.001), and an inverse relationship between injury duration and higher body mass index (t = −4.213, p < 0.001), highlighting how higher cellularity seems less prone to severe training injuries. Analyzing match-day injuries, right upper-limb higher reactance (XCArmdx) negatively correlates with match-day number of injuries (t = −4.469, p < 0.001), right upper limb resistance (RZArmDx) negatively correlates with lower match-day injury duration (t = −4.202, p < 0.001), and trunk resistance (RZTrunk) positive correlates with lower match-day injury duration (t = 2.803, p = 0.008), in contrast with the training data analysis. Analyzing the relationship between the BIVA parameters and performance indicators, right upper limb resistance (RzArmDx) has a positive link with plus–minus (t = 2.889, p = 0.007); however, RzArmDx negatively correlates with assist number (t = −3.362, p = 0.002), and BMI is directly proportional to assist number (t = 2.254, p = 0.032). These first data suggest a good correlation between the cellularity of different body districts and the risk of injuries in training but still leave several doubts surrounding the concrete predictive potential regarding performance and injuries during competitions while considering the numerous factors involved. Further studies on BIVA and similar applications could provide tools for managing athlete health and physical integrity preservation and potentially help us better understand the factors involved in improving performance.

Numerical simulation of changes in the electric properties of biological tissues under local heating by laser radiation

The mathematical model that describes the local heating of biological tissues by optical radiation is introduced. Changes of the electric properties of biological tissues in such process can be used as a reliable tool for analyzing heating and damage degrees of tissues.

A Goertzel Filter-Based System for Fast Simultaneous Multi-Frequency EIS

Bioimpedance measurement is a non-invasive, radiation-free, and inexpensive method for measuring the electrical properties of biological tissues. In applications where transients occur, the commonly used swept sinewave is replaced with broadband signals such as multisine. This makes the signal generation and the extraction of the real and imaginary parts of the impedance challenging. In this brief, an alternative to traditional fast Fourier transform (FFT) or coherent demodulation is presented. Based on the Goertzel filter, this alternative is simpler and requires very few digital resources. Its robustness to the harmonic fold back phenomenon, enables simple ternary current pulses to be used for excitation. The developed digital architecture is capable of simultaneous demodulation of 16 frequencies with an accuracy of 97% and 96% on the magnitude and phase measurement respectively. Employing a ternary sequence allows the use of a low power H-bridge current driver. The analog front-end and demodulation algorithm were implemented in an ASIC using a 180-nm CMOS technology. The system was tested on an isolated pig heart distinguishing edema from non-edema tissue by impedance changes.

Electrical Properties of Biological Tissues and Measurement Technology

Electrical Properties of Biological Tissues and Measurement Technology

Mathematical model of electrical conductivity of biological tissues based on ion electrodiffusion equations

A method for modeling of the electrical properties of biological tissues is introduced. It is based on the division of tissue in accordance with the geometry of living cells and the solution of the Nernst-Planck electrodiffusion equation for the calculation of ion currents between individual cells.

Memristive Bio-Impedance Modeling of Fruits and Vegetables

Recent works show that the plants can exhibit nonlinear memristive behavior when excited with low-frequency signals. However, in the literature, only linear bio-impedance models are extensively considered to model the electrical properties of biological tissues without acknowledging the nonlinear behavior. In this paper, we show with experiments, for the first time, the pinched hysteresis behavior in seven fruits and vegetables including tomato, orange, lemon, aubergine, and kiwi which exhibit single pinch-off point, and others such as carrot and cucumber exhibit double pinch-off points (i.e., three lobes). We also proposed a memristive fractional-order bio-impedance model by extending the Hayden bio-impedance model. The proposed model is used to fit the measurements of the seven fruits and vegetables showing very good matching.

Abstract 5484: Influence of the thermal and electric properties of biological tissues on the maximum temperature during TTFields therapy

Abstract Tumor Treating Fields (TTFields) is a non-invasive technique used in the treatment of glioblastoma. It consists in applying an electric field with a frequency of 200 kHz in two perpendicular directions alternately. This technique has an anti-mitotic effect if the induced field is at least 1 V/cm at the tumor bed. The Optune device, used to deliver these fields in real subjects, controls the injected current to keep scalp's temperature below potentially harmful values by controlling the temperature of the transducers. The thermal impact of this technique was recently predicted by our group. In this work we aim to investigate how the uncertainties regarding both the electric and thermal properties of tissues, transducers and gel affect the maximum temperature reached by each tissue and might affect the time that the device is applying the fields due to its thermal restrictions. We used a realistic head model created from MR images to perform our studies and run the simulations in COMSOL Multiphysics. After an extensive literature review, we selected a reasonable range of values for each property and performed a one-way sensitivity analysis. To obtain the temperature distribution we solved Pennes' equation in frequency domain studies. We observed that the most significant electric parameters are scalp, skull and gel's conductivity values. In general, an increase in the conductivity led to higher temperatures, as expected. In terms of changes in the temperature reached by the transducers it was seen that it can vary between +1.3°C (when scalp's conductivity is increased by a factor of 80% to 0.45 S/m) and -1.7°C (scalp's conductivity decreased to 0.14 S/m). The thermal parameters that are more critical are the ones that can directly change how quickly heat is transferred to the environment, namely scalp's properties. Transducer temperature varied between -0.6°C and +1.3°C when scalp's thermal conductivity was increased by 46% and decreased by 53%, respectively. Furthermore, the sweat rate and the convection factor and emissivity of the medical tape that covers the arrays also led to significant temperature variations. The latter analysis can be used to study new types of materials that can be more appropriate to apply these fields. The remaining electric (relative permittivity) and thermal (metabolic heat, blood perfusion, blood density and specific heat and thermal conductivity of skull, CSF and brain) parameters did not lead to significant temperature variations. These results show the importance of precisely knowing the most crucial physical properties in TTFields modelling studies. Due to the very strict current control injection mode of Optune based on the temperature of the transducers, it would be beneficial to experimentally measure the properties here discussed. Citation Format: Nichal Gentilal, Pedro Cavaleiro Miranda. Influence of the thermal and electric properties of biological tissues on the maximum temperature during TTFields therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5484.

Time Stamp - A Novel Time-to-Digital Demodulation Method for Bioimpedance Implant Applications.

Bioimpedance analysis is a noninvasive and inexpensive technology used to investigate the electrical properties of biological tissues. The analysis requires demodulation to extract the real and imaginary parts of the impedance. Conventional systems use complex architectures such as I-Q demodulation. In this paper, a very simple alternative time-to-digital demodulation method or 'time stamp' is proposed. It employs only three comparators to identify or stamp in the time domain, the crossing points of the excitation signal, and the measured signal. In a CMOS proof of concept design, the accuracy of impedance magnitude and phase is 97.06% and 98.81% respectively over a bandwidth of 10 kHz to 500 kHz. The effect of fractional-N synthesis is analysed for the counter-based zero crossing phase detector obtaining a finer phase resolution (0.51˚ at 500 kHz) using a counter clock frequency ( fclk = 12.5 MHz). Because of its circuit simplicity and ease of transmitting the time stamps, the method is very suited to implantable devices requiring low area and power consumption.

Sensibility analysis of the electrical impedance parameters by the Monte Carlo method

Electrical properties of biological tissues are used to analyze its state in different practical applications, e.g., assessing the risk of cancer. The modeling of electrical properties usually is performed by circuital models or semiempirical models as Cole-Cole. Still, another option is available, the application of the generalized effective medium theory of induced polarization. In the framework of the effective medium theory, we proposed a model for biological tissues which we called MOPET. This model links physiological parameters of tissues with their electrical properties. However, it has a higher number of parameters than the Cole-Cole and circuital models. This large number of parameters is a limitation for the use of effective medium theory to describe the electrical properties of tissue and also suggests that some of these parameters have negligible effects. We used a Monte Carlo simulation to study the effect of each MOPET parameter on the electrical impedance spectra, where uniform random variables were used to simulate the variability of the parameters of this model. We found that the heterogeneity coefficient is the most sensible parameter, i.e., a variation above 1% in this parameter alters enormously the impedance spectra.

Low-Cost, Compact, and Rapid Bio-Impedance Spectrometer with Real-Time Bode and Nyquist Plots

Bioelectric impedance spectroscopy (BIS) has been widely used to study the electrical properties of biological tissue based on the characteristics of the complex electrical impedance dispersions. One of the problems in using the BIS method is the length of time required for the data acquisition process and possibly data analysis as well. In this research, a compact and work rapidly BIS instrumentation system has been developed at a low cost. It is designed to work in the frequency range of 100 Hz to 100 kHz, which is generally used in the fields of biophysics and medical physics. The BIS instrumentation system is built using several integrated modules. The modules are an AC current source to produce a selectable injection current; a data acquisition system to measure voltage, current, and phase difference rapidly and simultaneously; and software to calculate and display measurement results in the form of Bode and Nyquist plots in real time. The developed BIS system has been validated using a simple RC circuit as the sample being tested. The average time needed in the process of data acquisition and analysis until the formation of impedance dispersion curves in the form of Bode and Nyquist plots, for 54 sample frequencies, is less than one minute. The system is able to identify R and C values of the sample with a maximum error of 1.5%. In addition, some simple application examples are also presented in this paper.

Information can be stored in the human skin memristor which has non-volatile memory

Much is already understood about the anatomical and physiological mechanisms behind the linear, electrical properties of biological tissues. Studying the non-linear electrical properties, however, opens up for the influence from other processes that are driven by the electric field or movement of charges. An electrical measurement that is affected by the applied electrical stimulus is non-linear and reveals the non-linear electrical properties of the underlying (biological) tissue; if it is done with an alternating current (AC) stimulus, the corresponding voltage current plot may exhibit a pinched hysteresis loop which is the fingerprint of a memristor. It has been shown that human skin and other biological tissues are memristors. Here we performed non-linear electrical measurements on human skin with applied direct current (DC) voltage pulses. By doing so, we found that human skin exhibits non-volatile memory and that analogue information can actually be stored inside the skin at least for three minutes. As demonstrated before, human skin actually contains two different memristor types, one that originates from the sweat ducts and one that is based on thermal changes of the surrounding tissue, the stratum corneum; and information storage is possible in both. Finally, assuming that different physiological conditions of the skin can explain the variations in current responses that we observed among the subjects, it follows that non-linear recordings with DC pulses may find use in sensor applications.

Tissue discrimination by bioelectrical impedance during PLL resection in anterior decompression surgery for treatment of cervical spondylotic myelopathy

BackgroundThe electrical properties of biological tissues differ depending on their physical properties. This study aimed to explore if bioelectrical impedance (modulus and phase) would discriminate tissues relevant to resection of the posterior longitudinal ligament (PLL) in anterior cervical decompression surgery.MethodsPLL resection via an anterior approach was performed on the C4/5 segments in six mini-pigs. The bioelectrical impedance measurements were performed for two tissue groups (annulus fibrosus, endplate cartilage, sub-endplate cortical bone, and PLL; PLL, dura mater, spinal cord, and nerve root) using a novel probe and a precision inductance-capacitance-resistance meter. For each group, impedance was analyzed in terms of modulus and phase along a broad spectrum of frequencies (200–3000 kHz) using a nonparametric statistical analysis (Kruskal-Wallis).ResultsThe analysis showed a clear difference among the tissues. The modulus and phase show the same changing trend with frequency and present lower values at higher frequencies. Among annulus fibrosus, endplate cartilage, sub-endplate cortical bone, and PLL, it was possible to discriminate each tissue at every frequency point, considering the phase (p < 0.05), while this was not always the case (i.e., annulus fibrosus vs PLL at frequency of 200 kHz, 400 kHz, and 3000 kHz, p > 0.05) for modulus. Among PLL, dura mater, spinal cord, and nerve root, for every comparison, a statistically significant difference was reported in the modulus, phase, or both (p < 0.05).ConclusionsThe results indicated the potential of bioelectrical impedance to provide real-time tissue differentiation and enhance safe PLL resection in anterior cervical decompression surgery, particularly in robot-assisted minimally invasive surgery (RMIS).

Three-dimensional model of thermoacoustic tomography with electric excitation

As the electrical properties of biological tissues are highly sensitive to their physiological and pathological status, the noninvasive imaging method of electrical properties also has drawn much attention. Thermo-acoustic tomography with electric excitation (TATE) is a typical noninvasive method of electrical properties for biological tissues. To the best of our knowledge, however, there is no 3D simulation model of TATE. In this paper, a new mathematical model is built, and the 3D TATE equations have been deduced. The performance of TATE has been studied by a series of 3D simulation models, including the tumors with different background tissues, different sizes, and different conductivities. In the simulation results, the Joule heat distribution of tumors has been imaged clearly. In addition, a verification experiment has validated the mathematical model and simulation results. The simulation and experiment results also indicate that the mathematical model can describe TATE well and TATE has the potential to image the tumors with high contrast and high resolution.

Construction of systems of frequency impedance metering of biological tissues using “Arduino” platforms

The electrical properties of biological tissue of vegetable origin are investigated, an algorithm for the functioning of the system for calculating the viability factor built on the basis of the “Arduino” platform is considered.

In-vivo Measurements of Tissue Impeditivity by Electrical Impedance Spectroscopy.

The electrical properties of biological tissues differ depending on their structural characteristics. In literature, a lot of study have been carried out with the intent of taking advantage of bioimpedance analysis. Unfortunately, many apparatuses used during these evaluations were not always designed for measurements on living tissues. As a consequence, data could be affected by electrode polarization. In 2016, we presented a new impedance meter, developed for measurements on living tissues. Initially, it was tested only on ex-vivo rabbit's tissues with promising results. As a continuation, this device has been tested on in-vivo samples by placing a needle-probe into 3 tissues (liver, spleen, ovary) of 2 female dogs. Furthermore, was evaluated also the bioimpedance signal of the ovary explanted, comparing it with the in-vivo data. Bioimpedance was analyzed in terms of modulus and phase along a broad spectrum of frequencies (10Hz - 10kHz).Data obtained confirm the possibility of discriminating among the 3 tested tissues, at high frequencies for modulus and at low for phase. Confirmation that values on in-vivo and exvivo tissues are comparable if detected within few minutes after the explant, is also reported. We conclude that this clinical evaluation confirmed, also in-vivo, the good performance of the device previously tested on ex-vivo tissues, and provide more information about the tissue properties and characteristics.