Electrical Cell-substrate Impedance Sensing (ECIS)法を用いた培養細胞の微細挙動の定量的評価法 - 細胞-細胞間隙と細胞-電極間隙の評価 -

We have proposed a mathematical model for the micro-dynamics for cultured cells measured with ECIS system for the detection of nanometer-order dynamics of cells cultured on a small gold electrode and could separately evaluate cell-to-cell distance (A) and cell-to-substrate distance (h). For wide applications of this method, we constructed mathematical models which express cell-to-electrode impedances for some kinds of confluent conditions. Based on this mathematical model, we defined new parameters S(A) and S(h) in order to evaluate cell-to-cell distance and cell-to-substrate distance. As the application, we investigated the effect of X-irradiation to bovine aortic endothelial cell (BAEC). We analyzed the micro-dynamics of cells from the impedance of BAEC before and after X-irradiation. It was proved that the stimulation of 100 Gy X-irradiation to the BAEC resulted in the large scale of increase in the cell-to-cell distances (A), and the slight increase in the cell-to-substrate distances (h) accompany with continuous fluctuations.[背景] Electrical Cell-substrate Impedance Sensing (ECIS)は培養細胞の電気的計測により,その微細挙動を評価する工学的手法である｡我々はECISを用いてこの微細挙動を細胞-細胞間隙と細胞-電極間隙に分離して推定することが可能な数学的モデルを提案してきた｡本研究ではこの数学的モデルを使用して,Ⅹ線を照射した牛大動脈内皮細胞(bovine aortic endothelial cell : BAEC)の微細挙動の経時変化を評価した｡ [方法と結果] ECISシステム(Model 1600R Applied BioPhysics)を用いてBAECのコンフルエント到達前後で計測を行い,数学的モデルを構築した｡このモデルは細胞の微細挙動を検出するために重要な周波数レンジである1-10kHzにおいて測定結果とよく一致し,Cole-Cole円弧則に従う｡さらに細胞-細胞間距離Aの増減に対応する校正定数S(A)と細胞-電極間距離hの増減に対応する校正定数S(h)を導入し,ベクトルインピーダンスの変化に対応した値を算出することで細胞の微細挙動を評価することとした｡次に本法によりX線(150kV, 100Gy)を照射したBAECの微細挙動を評価した｡Ⅹ線照射細胞では時間経過と共に抵抗成分の変化が支配的なインピーダンスの減少が確認された｡この現象はS(A)の大きな増加とS(h)の微小な減少をもたらした｡このパラメータの変化は細胞間隙が拡大したことを示しており,Ⅹ線照射による細胞内損傷により細胞密度が低下したと考えられた｡ [結論] 本法は培養細胞の微細動態の変化を細胞-細胞間隙と細胞-電極間隙に分けてリアルタイムに定量評価することが可能であり,各臓器の細胞レベルでの薬物の治療効果や Ⅹ線に対する耐性の評価に適応できるものと考える

Modeling of bioimpedance for human skin based on fractional distributed-order modified cole model

Eksperimentalni podaci otpornosti i računa necelobrojnog reda koriste se za modeliranje bioimpedansnih osobina ljudske kože. Uveli smo i predložili modifikovani Kole model koristeći pri tom operator distribuiranog necelog reda koji je zasnovan na Caputo-Weyl-ovim izvodima necelog reda.Naš predloženi model predstavlja izmenjen jedno-disperzijski Kole model, jer uvodi nove parametre k i σ u jedno-disperzijskoj Kole impedansnoj jednačini. Ovi parametri karakterišu širinu intervala oko frakcionog indeksa α i oni su važni za precizniji opis bioimpedansnih osobina ljudske kože. Predloženi modifikovani Kole model mnogo bolje daje fitovanje date eksperimentalne krive u datom frekventnom opsegu u poređenju sa sa postojećim Kole modelima. Fitovanje je urađeno primenom Levenberg-Marquardt algoritma nelinearnih najmanjih kvadrata.Electrical impedance measurement data and fractional calculus have been utilized for modeling bioimpedance properties of human skin. We introduced and proposed revisited Cole model using modified distributed order operator based on the Caputo-Weyl fractional derivatives. Our proposed model presents essentially modified single-dispersion Cole model, since it introduces a new parameters k and σ in single-dispersion Cole impedance equation. These parameters characterize the width of interval around fractional index α and they are important for more accurate describing bioimpedance properties of human skin. The impedance spectrum was measured in a finite frequency range up to 100 kHz. Our proposed modified Cole model fits much better to experimental curve in a given frequency range compared to existing Cole models. The fitting is done using the Levenberg-Marquardt nonlinear least squares

Modeling of bioimpedance for human skin based on fractional distributed-order modified cole model

Eksperimentalni podaci otpornosti i računa necelobrojnog reda koriste se za modeliranje bioimpedansnih osobina ljudske kože. Uveli smo i predložili modifikovani Kole model koristeći pri tom operator distribuiranog necelog reda koji je zasnovan na Caputo-Weyl-ovim izvodima necelog reda.Naš predloženi model predstavlja izmenjen jedno-disperzijski Kole model, jer uvodi nove parametre k i σ u jedno-disperzijskoj Kole impedansnoj jednačini. Ovi parametri karakterišu širinu intervala oko frakcionog indeksa α i oni su važni za precizniji opis bioimpedansnih osobina ljudske kože. Predloženi modifikovani Kole model mnogo bolje daje fitovanje date eksperimentalne krive u datom frekventnom opsegu u poređenju sa sa postojećim Kole modelima. Fitovanje je urađeno primenom Levenberg-Marquardt algoritma nelinearnih najmanjih kvadrata.Electrical impedance measurement data and fractional calculus have been utilized for modeling bioimpedance properties of human skin. We introduced and proposed revisited Cole model using modified distributed order operator based on the Caputo-Weyl fractional derivatives. Our proposed model presents essentially modified single-dispersion Cole model, since it introduces a new parameters k and σ in single-dispersion Cole impedance equation. These parameters characterize the width of interval around fractional index α and they are important for more accurate describing bioimpedance properties of human skin. The impedance spectrum was measured in a finite frequency range up to 100 kHz. Our proposed modified Cole model fits much better to experimental curve in a given frequency range compared to existing Cole models. The fitting is done using the Levenberg-Marquardt nonlinear least squares

Impedimetric Analysis of Trabecular Bone Based on Cole and Linear Discriminant Analysis

A spatially unambiguous characterization of electrical properties of osseous tissues is important for the therapy of osteopathy via electrical stimulation. Accordingly, the study aimed to characterize the highly inhomogeneous composition and structures of different anatomical regions of trabecular bone based on their electrical properties. The electrical properties of 64 porcine trabecular bone samples were analyzed in a parallel plate electrode configuration and compared with published results. Therefore, a novel method, combining traditional Cole model with a linear discriminant analysis (LDA), was developed to discriminate the different regions, i.e., femur head, greater trochanter, and femur neck. Possible mechanisms behind the distinction for different regions could be interpreted from both methods. Respective adjacent regions with similar structure and composition could be distinguished from statistically significant differences of Cole parameters, i.e., α (p < 0.01) and R∞ (p < 0.05). The latter was correlated especially with water content, indicating an association of individual differences in microstructures in particular with conductivity. Conversely, different regions were unambiguously discriminated with LDA based on permittivity or conductivity. Contributions to the discrimination were explicitly reflected by the coefficients of the derived LDA features. A clear distinction was obtained especially for a frequency response at 950 kHz. Moreover, predictions for the classification of unspecified samples assigned them correctly to their origin with a success of 92.9%. The combination of both methods offers the possibility for a spatially resolved and eventually patient specific discrimination and evaluation of bone tissues and their response to therapies, notably electrical stimulation

Short, Multineedle Frequency Domain Reflectometry Sensor Suitable for Measuring Soil Water Content

Time domain reflectometry (TDR) is a well-established electromagnetic technique used to measure soil water content. Time domain reflectometry sensors have been combined with heat pulse sensors to produce thermo-TDR sensors. Thermo-TDR sensors are restricted to having relatively short needles to accurately measure soil thermal properties. Short needle lengths, however, can limit the accuracy of the TDR measurement of soil water content. Frequency domain reflectometry (FDR) sensors are an alternative to TDR sensors that can provide an inexpensive measurement of soil water content. The objective of this study was to determine whether short FDR sensors can accurately measure soil water content. We designed and constructed a short FDR sensor. For four soil types across a range of water contents, temperatures, and salt contents, we measured soil dielectric spectra with the short FDR sensor. A vector network analyzer was used to obtain soil dielectric spectra in the 1-MHz to 3-GHz frequency range. The ideal frequency of a short FDR sensor is the frequency at which the permittivity is not altered by changing temperature or salt content. The 47- to 200-MHz range was an ideal frequency range for measuring soil water content, and 70 MHz was the frequency least influenced by temperature and salt content. The short FDR sensor provided quick, continuous, stable, and cheap measurements of soil water content. Because of the promising performance of the short thermo-FDR sensor in laboratory studies, sensors should be evaluated in future field studies

Biological Cell Identification by Integrating Micro-fluidics, Electrical Impedance Spectroscopy and Stochastic Estimation

The integration of micro-fluidics, electrical impedance spectroscopy and stochastic estimation will lead to a device with enhanced detection capabilities. The goal of this thesis was to build a micro-fluidic electrical impedance measurement device that can be used in combination with a stochastic estimator to accurately identify living cells. A microdevice capable of making impedance measurements on individual living cells was designed and built using a series of standard microelectronic fabrication techniques. A microchannel was patterned in SU-8 photoresist between two gold microelectrodes on a two inch Pyrex 7740 wafer. The design process, the fabrication techniques for the microchannel, the fluid port fabrication and the cover slip bonding processes are described in detail. Small glass cover slips were bonded to the wafer using Loctite 3301 adhesive. Impedance measurements of single cells, in the microchannel device, were made using a HP4194A impedance analyzer. Preliminary analysis of the impedance data suggests that Jurkat cells have characteristic impedance signatures, corresponding to their cell type. The microdevice that was designed and built for this project should facilitate future work to implement a stochastic estimation algorithm capable of single cell identification

In silico study on in vitro experiments to determine the electric membrane properties of a realistic cochlear model for electric field simulations on cochlear implants

To further develop and optimise the design of cochlear implants, a numerical model with precise material properties and authentic geometry is required. Since simulation results strongly depend on the accuracy of the estimates of the electrical properties of cochlear membranes, it is important to have a reliable in vivo method for measuring electrical impedance changes in the cochlear compartments. This work is a preliminary attempt to model, simulate and analyse the behaviour of a novel in-vitro experimental system for conducting plausible in-vivo measurements on mammalian cochlea membranes.Zur Weiterentwicklung und Optimierung des Designs von Cochlea-Implantaten ist ein detailliertes numerisches Modell der Cochlea erforderlich. Da die Simulationsergebnisse stark von den elektrischen Eigenschaften der Cochlea-Membranen abhängen, ist es wichtig, ein zuverlässiges In-vivo-Verfahren zur Messung des elektrischen Impedanzverlaufs zu haben. Diese Arbeit ist eine vorbereitende Studie, das Verhalten eines neuartigen In-vitro-Versuchssystems zur Durchführung plausibler In-vivo-Messungen an Cochlea-Membranen von Säugetieren zu modellieren, zu simulieren und zu analysieren

Elektrisk impedansspektroskopi for non-invasiv måling av laktat i biologisk vev

Ved høy fysisk belastning produserer musklene mye laktat, noe som fører til at den høye arbeidsbelastningen ikke kan opprettholdes særlig lenge. Idrettsutøvere vil gjerne vite hvor høy konsentrasjon av laktat de har ved ulike arbeidsbelastninger, fordi det er en god objektiv indikator på hvor godt kroppen tåler belastningen. Laktatkonsentrasjon måles i dag ved å ta en blodprøve. I denne oppgaven ble det undersøkt om en målemetode basert på bioimpedans kunne gi informasjon om laktatkonsentrasjonen i kroppen ved ulike arbeidsbelastninger. Det ble utført fysiologiske tester på 11 forsøkspersoner med Solartron 1260 og 1294 bioimpedans-analysator, sammen med etablerte målemetoder av laktatkonsentrasjon i blodet. Et fireelektrodeoppsett ble benyttet. Et datasett med et impedansspekter og en laktatkonsentrasjon ble innhentet ved 8-14 ulike ergometersykkelbelastninger fra hver forsøksperson. Multivariatanalyse ble utført på måledataene, for å finne en korrelasjon mellom laktat og impedans. Til sammen 127 datasett med impedans og laktatverdier ble analysert. Det viste seg at impedansdataene var ulike fra forsøksperson til forsøksperson. Volum av det målte lårsegmentet og forsøkspersonens fettprosent gjorde trolig utslag på impedansen, noe som igjen førte til at resultatet av multivariatanalysen ikke ble bra da all impedansdata ble analysert sammen. Men hver for seg, og to forsøkspersoner i samme multivariatanalyse gav lovende korrelasjon mellom laktatkonsentrasjon og impedansdata. For at man med større sikkerhet skulle kunne finne hvilke observasjoner som skyldes endring i laktatkonsentrasjonen ble det utført forsøk på en cellesuspensjon. Impedans ble målt på samme måte som på forsøkspersoner ved ulike laktatkonsentrasjoner i cellesuspensjonen. Resultatene av disse forsøkene ble ikke gode siden volumkonsentrasjonen av cellene ikke var stor nok, og måleoppsettet ikke var godt nok