Analysis and Application of Analog Electronic Circuits to Biomedical Instrumentation

Northrop, Robert B.

doi:10.1201/9780203492734

Cited by 35 publications

(19 citation statements)

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“…However, electronic amplifiers required the addition of a further limb to the ECG measurement that original inventors of the system had not taken into account: the "right leg." Remembering that electronic amplifiers, by construction and design, are better equipped to measure voltages rather than currents [5][6][7], and also bearing in mind that an additional reference terminal may be required for common mode signal rejection reasons, particularly at power-line frequencies [7][8][9][10], it was a natural choice for engineers to connect this additional terminal to the right leg [8,9]. The right leg was traditionally excluded from the original Einthoven/Wilson ECG model because the string galvanometer measures directly the current circulating into the surrounding tissues as a consequence of the shift in the electromagnetic field impressed by the heart's activation.…”

Section: Introductionmentioning

confidence: 99%

On the “Zero of Potential of the Electric Field Produced by the Heart Beat”. A Machine Capable of Estimating this Underlying Persistent Error in Electrocardiography

et al. 2016

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Modern electrocardiography (ECG) uses a constructed reference potential for the majority of leads. This reference potential, named after its inventor as the Wilson central terminal, is assumed to have negligible value and to be stationary during the cardiac cycle. However, the problem of its variability during the cardiac cycle has been known almost since the inception of 12-lead electrocardiography. Due to the cumbersomeness of the measurement system required to fully appreciate these variations, this topic has received scant research attention during the last 60 years. Taking advantage of modern electronic amplifiers' capability to detect small voltages, drawing only femtoamperes from physiological equivalent signal sources and of the right-leg connection availability, we developed a complete electrocardiography device that, aside from the eight independent signals of the standard 12-lead ECG, allows direct recording of the Wilson central terminal components. In this paper, we present details of the circuit together with its initial clinical evaluation. For this trial, we recorded data from 44 volunteer patients at Campbelltown Hospital (Campbelltown, Australia) and we found that the Wilson central terminal amplitude, as foreseen by Frank and others in the 1950s, is not negligible, its amplitude in relation to the lead II is, on average, 51.2%, and thus it may be clinically relevant.

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Section: Introductionmentioning

confidence: 99%

On the “Zero of Potential of the Electric Field Produced by the Heart Beat”. A Machine Capable of Estimating this Underlying Persistent Error in Electrocardiography

et al. 2016

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“…Com o transcorrer do tempo, como mostra o Quadro 1, descobertas e o uso de campos eletromagnéticos (CEM) evoluíram de diferentes maneiras. Atualmente, pesquisas com aplicação de CEM em seres humanos objetivam diagnóstico 3,4 e tratamento 1 . Além da saúde humana e agronomia, por exemplo, CEM são empregados em estudos com plantas, frutos e sementes proporcionando germinação e crescimento diferenciados das espécies convencionais 1,5 .…”

Section: Introductionunclassified

Campos elétricos e magnéticos aplicados à regeneração nervosa periférica

et al. 2011

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RESUMOIntrodução. campos eletromagnéticos (CEM) são utilizados com objetivos reabilitacionais no corpo humano. A lesão no tecido nervoso periférico diferencia-se da lesão no sistema nervoso central por apresentar grande potencial de regeneração axonal. Uma série de efeitos fisiológicos é associada à exposição de CEM, como analgesia, vasodilatação, contração muscular e, principalmente, regeneração de tecidos. Objetivo. apresentar aplicações dos CEM para a viabilidade na reabilitação do tecido nervoso periférico. Método. pesquisa bibliográfica realizada nas bases Springer, ScienceDirect, Pubmed, Google Acadêmico, portal de periódicos da CAPES entre os anos 1972 a 2009, empregando os termos: Magnetic fields; Nerve regeneration; Peripheral nerve; Axonal regeneration; Electrical regeneration; Peripheral nerve regeneration. Resultados. os parâmetros selecionados para os CEM variam amplamente: campos elétricos utilizam duração do pulso (período ativo) de 65 µs a 100 µs, frequência entre 0 a 250 Hz e amplitude entre 0,1 V/m a 4 V/m. Para campos magnéticos, a intensidade varia entre 4,35 µT e 8 T e a frequência entre 0 a 54 GHz. Conclusão. resultados da aplicação de CEM em tecido animal estão relacionados ao alongamento e direcionamento axonal, incremento protéico, alteração genética e redução do tempo total de regeneração. A aplicação de CEM não produz danos físicos, com poucos efeitos colaterais transitórios quando utilizados com magnitudes consideradas seguras.Unitermos. Regeneração Nervosa, Regeneração Tecidual Guiada, Sistema Nervoso, Sistema Nervoso Periférico, Engenharia Biomé-dica, Reabilitação.Citação. Krueger-Beck E, Scheeren EM, Nogueira Neto GN, Nohama P. Campos elétricos e magnéticos aplicados à regeneração nervosa periférica. ABSTRACTIntroduction. Electromagnetic fields (EMF) may be applied to the human body with rehabilitative goals. Injury to peripheral nerve tissue differs from the lesion in the central nervous system because it presents a great potential for axonal regeneration. physiological effects are associated to exposure to EMFs, such as analgesia, vasodilation, muscle contraction and, especially, tissue regeneration. Objective. The paper aim is present and explore new applications of EMF in the rehabilitation of peripheral nerve tissue. Method. Literature search was undertaken on the bases Springer, ScienceDirect, PubMed, Google Scholar, CAPES periodicals portal between the years 1972 to 2009, using the terms: Magnetic fields; Nerve regeneration; Peripheral nerve; Axonal regeneration; Electrical regeneration; Peripheral nerve regeneration. Results. The selected parameters for EMFs vary widely: for electric fields, it is used pulse width (on time) from 65 µs up to 100 µs, frequency range up to 250 Hz and amplitude varying from 0,1 V/m to 4 V/m. For magnetic fields, intensity varies between 4.35 µT and 8 T and frequency, between 0 and 54 GHz. Conclusion. results related to axonal elongation and guidance, protein increment, genetic changes and reduction of the total time of regeneration. The applica...

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“…These sensors can be used for online monitoring, detection and prevention of many diseases with a minimum disturbance to the patient and reducing the hospital expenses, so they are having a big acceptance in the medical community. Most biomedical signals are characterized by their low voltage amplitude (in the range of mili-volts) and their low frequency ranges (few tens of kHz) (Northrop, 2001;Northrop, 2004). Also, due to the electrode used to sense them, they usually present a high DC offset that needs to be suppressed.…”

Section: Introductionmentioning

confidence: 99%