임피던스 변환 회로를 이용한 건식능동뇌파전극 개발

고덕원,이관택,김성민,이찬희,정영진,임창환,정기영 대한임상신경생리학회 2011 Annals of Clinical Neurophysiology Vol.13 No.2

Background: A dry-type electrode is an alternative to the conventional wet-type electrode, because it can be applied without any skin preparation, such as a conductive electrolyte. However, because a dry-type electrode without electrolyte has high electrode-to-skin impedance, an impedance-converting amplifier is typically used to minimize the distortion of the bioelectric signal. In this study, we developed an active dry electroencephalography (EEG) electrode using an impedance converter, and compared its performance with a conventional Ag/AgCl EEG electrode. Methods: We developed an active dry electrode with an impedance converter using a chopper-stabilized operational amplifier. Two electrodes, a conventional Ag/AgCl electrode and our active electrode, were used to acquire EEG signals simultaneously, and the performance was tested in terms of (1)the electrode impedance, (2) raw data quality, and (3) the robustness of any artifacts. Results: The contact impedance of the developed electrode was lower than that of the Ag/AgCl electrode (0.3±0.1 vs. 2.7±0.7 kΩ, respectively). The EEG signal and power spectrum were similar for both electrodes. Additionally, our electrode had a lower 60-Hz component than the Ag/AgCl electrode (16.64 vs. 24.33 dB, respectively). The change in potential of the developed electrode with a physical stimulus was lower than for the Ag/AgCl electrode (58.7±30.6 vs. 81.0±19.1 μV, respectively), and the difference was close to statistical significance (P=0.07). Conclusions: Our electrode can be used to replace Ag/AgCl electrodes, when EEG recording is emergently required, such as in emergency rooms or in intensive care units.

Electro-deposited Nanoporous Platinum Electrode for EEG Monitoring

김도윤,구윤서,안중우,권치헌,김희찬 대한의학회 2018 Journal of Korean medical science Vol.33 No.21

Background: One of the key issues in electroencephalogram (EEG) monitoring is accurate signal acquisition with less cumbersome electrodes. In this study, the L2 phase electro- deposited nanoporous platinum (L2-ePt) electrode is introduced, which is a new type of electrode that utilizes a stable nanoporous platinum surface to reduce the skin-electrode impedance. Methods: L2-ePt electrodes were fabricated using electro-deposition technique. Then, the effect of the nanoporous surface on the surface roughness and the electrode impedance were observed from the L2-ePt electrodes and the flat platinum (FlatPt) electrode. The skin-electrode impedances of the L2-ePt electrodes, a gold cup electrode, and the FlatPt electrode were evaluated when placed on the hairy occipital area of the head in ten subjects. For the validation of using the L2-ePt electrode, a correlational analysis of the alpha rhythms was performed in the same subjects for simultaneous EEG recordings using the L2-ePt and clinically-used EEG electrodes. Results: The results indicated that the L2-ePt electrode with a roughness factor of 200 had the lowest mean impedance performance. Moreover, the proposed L2-ePt electrode showed a significantly lower mean skin-electrode impedance than the FlatPt electrode. Finally, the EEG signal quality recorded by the L2-ePt electrode (r = 0.94) was comparable to that of the clinically-used gold cup electrode. Conclusion: Based on these results, the proposed L2-ePt electrode is suitable for use in various high-quality EEG applications.

생체 임피던스를 이용한 인체 하지운동 출을 위한 최적 전극위치 선정

송철규,윤대영,이동헌,김승찬,김덕원 대한전기학회 2003 전기학회논문지 D Vol.53 No.8

This paper describes the possibility of analyzing gait pattern from the changes of the lower leg electrical impedance. This impedance was measured by the four-electrode method. Two current electrodes were applied to the thigh, knee, and foot., and two potential electrodes were applied to the lateral, medial, and posterior position of human leg. The correlation coefficients of the joint angle and the impedance change from human leg movement was obtained using a electrogoniometer and 4ch impedance measurement system developed in this study. We found the optimal electrode position for knee and ankle joint movements based on high correlation coefficient, least interference, and maximum magnitude of impedance change. The correlation coefficients of the ankle, knee, and the hip movements were -0.913, 0.984 and 0.823, respectively. From such features of the human leg impedance, it has been made clear that different movement patterns exhibit different impedance patterns and impedance level. This system showed feasibility that lower leg movement could be easily measured by impedance measurement system with a few skin-electrodes.

금 전극을 이용한 동물 조직 내 임피던스 측정연구

김민수(Min Soo Kim),조영창(Young Chang Cho) 한국전기전자학회 2021 전기전자학회논문지 Vol.25 No.3

생체임피던스 측정법은 편리성, 저비용 및 저가의 장치를 이용하여 생체정보 획득 및 피부 병 진단 등에 사용 가능한 장치이다. 본 연구에서는 생체 삽입형으로 생체 정보를 획득하기 위해서 동물 생체 모델링을 통한 시뮬레이션 연구와 직접 제작한 건식용 금 전극을 이용하여 생체임피던스를 측정하였다. 동물 조직의 피하부위에 전극을 삽입하여 2 전극법으로 100 uA, 1-100 kHz 주파수를 인가하여 임피던스를 측정하였다. 측정결과 전극의 사이즈를 5 mm전극기준으로 7.5 mm, 10 mm전극과 비교하여 저항을 측정한 결과 5 mm 전극에서 높게 측정됨을 확인할 수 있다. 5 mm전극을 기준으로 7.5 mm 전극은 전체 주파수 범위에서 평균 1.49 %차이를 발견하였고, 10 mm 전극은 2.624 %로 임피던스가 차이남을 확인하였다. 향후, 연구결과는 생체 삽입형 심전도 센서 전극 설계 및 제작 등에 활용가치가 있을 것으로 사료된다. Bio-impedance measurement is a measurement device that can be used to obtain biometric information and diagnose skin diseases using convenience, low cost, and low cost devices. In this study, the bio-impedance was measured using a direct dry gold electrode and a simulation study through animal bio modeling to obtain biometric information in a biometric form. Impedance was measured by inserting electrodes into subcutaneous areas of animal tissue and applying frequencies of 100 uA, 1-100 kHz using a two-electrode method. As a result of the measurement, the resistance of the electrodes is measured high at 5 mm electrodes compared to 7.5 mm and 10 mm electrodes based on 5 mm electrodes. Based on the 5 mm electrode, an average difference of 1.49% was found for the 7.5 mm electrode in the total frequency range, and the impedance difference was confirmed to be 2.624% for the 10 mm electrode. In the future, the research results are expected to be valuable in designing and manufacturing electrodes for bio-inserted electrocardiogram sensors.

탄소혼합물 접지전극의 접지임피던스의 특성

이강수(Kang-Soo Lee),이복희(Bok-Hee Lee) 한국조명·전기설비학회 2011 조명·전기설비학회논문지 Vol.25 No.5

This paper presents characteristics of frequency-dependent grounding impedance and transient grounding impedance for the carbon compound grounding electrode used in the installation of computerized electronic equipment and lightning protection system. The frequency-dependent grounding impedances were measured by applying sinusoidal currents in the frequency range from 100 [㎐] to 10[㎒], and the transient grounding impedances were examined by subjecting the impulse current with the front-time between 1∼80[㎲]. As a result, the ground resistance of the carbon compound grounding electrode is less than that of another type grounding electrodes. The transient grounding impedance is relatively low and the conventional grounding impedance is rather lower than the ground resistance. The frequency-dependent grounding impedance of the carbon compound grounding electrode is capacitive and the grounding impedance is decreased with increasing the frequency of injected currents. Therefore in the case that the carbon compound grounding electrode is jointly used with large-scaled grounding electrodes, it is possible to reduce the high frequency grounding impedance of the integrated grounding electrode system.

탄소접지극 접지임피던스의 주파수의존성과 과도응답특성의 해석

이복희(Bok-Hee Lee),이강수(Kang-Soo Lee),김유하(You-Ha Kim),엄상현(Sang-Hyun Um) 한국조명·전기설비학회 2013 조명·전기설비학회논문지 Vol.27 No.2

This paper presents transient response behavior and frequency-dependent ground impedance of a single carbon ground electrode. The ground impedance of the carbon ground electrode was measured as a function of frequency of injected currents and simulated by using the distributed parameter circuit model with due regard to the frequency-dependent soil parameters, and the transient response behavior of the carbon ground electrode against impulse currents were investigated. As a consequence, the frequency-dependent ground impedance of the carbon ground electrode showed the capacitive behavior, that is, the ground impedance decreases with increasing the frequency of injected currents and lowers at the fast front time of impulse current. It was found that the carbon ground electrode is effective in grounding system for lightning protection. The ground impedance simulated with due regard to the frequency-dependent soil parameters was in good agreement with the measured data. The adequacy of the simulation technique and the distributed parameter circuit model for the carbon ground electrode was verified. It is expected that the simulation methodology, which analyzes the frequency-dependent ground impedance of the carbon ground electrode proposed in this work, can be used in the design of a grounding system for protection against lightning.

Electrochemical impedance spectroscopy with interdigitated electrodes at the end of hypodermic needle for depth profiling of biotissues

Yun, Joho,Kang, Giseok,Park, Yangkyu,Kim, Hyeon Woo,Cha, Jung-Joon,Lee, Jong-Hyun Elsevier 2016 Sensors and actuators. B Chemical Vol.237 No.-

<P><B>Abstract</B></P> <P>An EoN (electrochemical impedance spectroscopy-on-a-needle) with bipolar interdigitated electrodes fabricated at the end of a curved surface of a hypodermic needle has been introduced to electrically discriminate biotissues. A flexible photomask and photoresist spray coating were employed in the photolithography process to fabricate fine electrode patterns on the round surface of the needle, which was insulated with parylene C. The electrodes were coated again with parylene C to enhance biocompatibility and durability. A repeatability test using a PBS (phosphate buffered saline) solution with known properties was carried out ten times; the maximum standard deviation was approximately 7% in electrical impedance. To analyze the EoN as an electrical circuit, equivalent modeling was introduced for the design of EIS (electrochemical impedance spectroscopy) devices with a target performance. In order to evaluate the discrimination capability of the EoN, the electrical depth profiling was conducted for three-layered (fat-muscle-fat) porcine tissues over a frequency range of 100Hz–1MHz as the needle sequentially penetrated the biotissues. The discrimination index (DI), defined as the ratio of the mean difference and the square root of sum of two variances, was introduced to find the optimal frequency at which the largest DI occurred for two boundaries of three-layered tissues. To improve the DI, the measured electrical impedance of three-layered porcine tissue was compensated by excluding the unwanted measurement error induced by the connection lines inserted in the biotissues. As a result, the discrimination index was considerably increased by 9.3 times in real (Z′) part of impedance and 3 times in imaginary (Z′′) part of impedance. We believe that the proposed EoN can be utilized to find the exact location of specific tissues and to discriminate between normal and abnormal lesion tissues prior to biopsy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The interdigitated electrodes were fabricated at the end of the hypodermic needle. </LI> <LI> The equivalent circuit of the EoN was analyzed for the design of device. </LI> <LI> For the first time, the electrical depth profiling was conducted for three-layered porcine tissue. </LI> <LI> The discrimination index was introduced to find the optimal frequency. </LI> <LI> The measured impedance was compensated by excluding the unwanted measurement error. </LI> </UL> </P>

나피온 폴리머를 이용한 금 전극의 표면 개질 및 이의 삼투압 측정용 임피던스 센서 응용

길민식 ( Min Sik Kil ),김민재 ( Min Jae Kim ),윤조희 ( Jo Hee Yoon ),장진우 ( Jinwu Jang ),이경균 ( Kyoung G. Lee ),최봉길 ( Bong Gill Choi ) 한국공업화학회 2023 공업화학 Vol.34 No.1

본 논문에서는 용액의 이온 농도 측정이 가능한 나피온 폴리머(Nafion polymer) 코팅 기반 2상 금 전극의 임피던스(Impedance) 센서를 개발하였다. 스퍼터링(Sputtering) 공정을 통해서 제작된 금 전극의 표면을 나피온 폴리머를 사용하여 표면 개질 하였다. 상기 제작된 전극은 분극 현상 제어가 가능하여 전기화학적 신호를 안정적으로 측정할 수 있도록 하였다. 분광학과 전자주사현미경 관찰을 통하여 박막의 나피온 폴리머 코팅을 확인하였다. 나피온 코팅이 된 전극은 기존 금 전극에 비해 안정적인 임피던스 신호를 보여 주었으며, 표준 염화나트륨(NaCl) 용액 사용 시 임피던스 센서의 신뢰성 높은 검정 곡선(R² = 0.983)을 나타내었다. 또한, 임피던스 센서는 상용화 전도도 장치와 인공 눈물의 이온 농도 측정 비교 실험을 진행하였으며, 유사한 결과값을 확인하였다. In this work, we developed a Nafion polymer-coated impedance sensor with two gold electrode configurations to measure the ion concentration in solution samples. The gold electrodes were fabricated through the sputtering process, followed by surface modification using Nafion polymer. The resulting sensors enable the prevention of the polarization phenomenon on the electrode surface, resulting in stable measurement of electrochemical signals. Spectroscopy and scanning electron microscopy measurements revealed that the thin film of Nafion was coated uniformly onto the surface of the gold electrode. The Nafion-coated sensor exhibited more stable impedance signals than the conventional gold electrode. It showed a highly reliable calibration curve (R² = 0.983) of the impedance sensor using a standard sodium chloride solution. In addition, a comparison experiment between the impedance sensor and a commercial conductivity sensor was performed to measure the ion concentration of artificial tears, showing similar results for the two sensors.

Effective Impulse Impedances of Deeply Driven Grounding Electrodes

Lee, Bok-Hee,Jeong, Dong-Cheol,Lee, Su-Bong,Chang, Keun-Chul The Korean Institute of Electrical Engineers 2004 KIEE International Transactions on Electrophysics Vol.4C No.5

This paper presents the characteristics of transient and effective impulse impedances for deeply driven grounding electrodes used in soil with high resistivity or in downtown areas. The laboratory test associated with the time domain performance of grounding piles subjected to a lightning stroke current has been carried out using an actual-sized model grounding system. The ground impedances of the deeply driven ground rods and grounding pile under impulse currents showed inductive characteristics, and the effective impulse ground impedance owing to the inductive component is higher than the power frequency ground impedance. Both power frequency ground impedance and effective impulse ground impedance decrease upon increasing the length of the model grounding electrodes. Furthermore, the effective impulse ground impedances of the deeply driven grounding electrodes are significantly amplified in impulse currents with a rapid rise time. The reduction of the power frequency ground impedance is decisive to improve the impulse impedance characteristics of grounding systems.

정상 삽입 인공와우 전극의 수술 중 감시 3례

허승덕,이상흔,김이혁,정다영 대한치료과학회 2020 대한치료과학회지 Vol.12 No.2

Objective: Cochlear implantation is the process of inserting a very small and soft electrode into the intrascalar. During surgery, the electrode can be kink or failure, and the internal structure of the cochlea can be damaged by the electrode tip. The study aims to retrospectively analyze the electrode-to-tissue impedance(electrode impedance), voltage compliance, stimulation artifact, electrically compound action potential(ECAP) implemented during the surgery to examine the clinical implication with a literature review. Participants & Method: The participants are three 70 to 76-year-old male implantee to whom MedEl's synchrony(Flex 28) implanted to the left ear. Results: The electrode impedance was observed in 1.69 to 8.25 ㏀, the voltage compliance was observed in 0.52 to 2.38 V, and the inter-channel voltage compliance be ranging from 0.11 to 0.38 V, respectively. In each channels, the baseline of the ECAP waveform was consistently observed, and the threshold of ECAP was observed to be ranging from 7.7 to 26.1 qu. Conclusion: In conclusion, intraoperative monitoring of electrode integrity during the surgery, the malfunctioning of the device together with the various issue that stem the surgery process can be discovered, hence resulting in obtaining valuable proof in solving the issues detected.