AC-coupled front-end for biopotential measurements

AC coupling is essential in biopotential measurements. Electrode offset potentials can be several orders of magnitude larger than the amplitudes of the biological signals of interest, thus limiting the admissible gain of a dc-coupled front end to prevent amplifier saturation. A high-gain input stage needs ac input coupling. This can be achieved by series capacitors, but in order to provide a bias path, grounded resistors are usually included, which degrade the common mode rejection ratio (CMRR). This paper proposes a novel balanced input ac-coupling network that provides a bias path without any connection to ground, thus resulting in a high CMRR. The circuit being passive, it does not limit the differential dc input voltage. Furthermore, differential signals are ac coupled, whereas common-mode voltages are dc coupled, thus allowing the closed-loop control of the dc common mode voltage by means of a driven-right-leg circuit. This makes the circuit compatible with common-mode dc shifting strategies intended for single-supply biopotential amplifiers. The proposed circuit allows the implementation of high-gain biopotential amplifiers with a reduced number of parts, thus resulting in low power consumption. An electrocardiogram amplifier built according to the proposed design achieves a CMRR of 123 dB at 50 HzPeer Reviewe

A novel fully differential biopotential amplifier with DC suppression

Fully differential amplifiers yield large differential gains and also high common mode rejection ratio (CMRR), provided they do not include any unmatched grounded component. In biopotential measurements, however, the admissible gain of amplification stages located before dc suppression is usually limited by electrode offset voltage, which can saturate amplifier outputs. The standard solution is to first convert the differential input voltage to a single-ended voltage and then implement any other required functions, such as dc suppression and dc level restoring. This approach, however, yields a limited CMRR and may result in a relatively large equivalent input noise. This paper describes a novel fully differential biopotential amplifier based on a fully differential dc-suppression circuit that does not rely on any matched passive components, yet provides large CMRR and fast recovery from dc level transients. The proposed solution is particularly convenient for low supply voltage systems. An example implementation, based on standard low-power op amps and a single 5-V power supply, accepts input offset voltages up to /spl plusmn/500 mV, yields a CMRR of 102dB at 50 Hz, and provides, in accordance with the AAMI EC38 standard, a reset behavior for recovering from overloads or artifactsPeer Reviewe

DE-NOISING ECG SIGNALS CONTAMINATED WITH POWER LINE INTERFERENCE USING NOTCH PRE-FILTERED WAVELET

This paper presents the fusion of Notch filter and Wavelet Transform method for denoising ECG signals contaminated with Power line interference. The objective results are compared qualitatively as well as quantitatively while the effectiveness of the method is also validated by Comparing the obtained results with traditional notch filters as well as the wavelet denoising method. The simulation results demonstrate that the purposed method is most effective for removal of power line interference in terms of fast time convergence as well as less complexity of the deployed algorithm.&nbsp

Problems in assessment of novel biopotential front-end with dry electrode:A brief review

Developers of novel or improved front-end circuits for biopotential recordings using dry electrodes face the challenge of validating their design. Dry electrodes allow more user-friendly and pervasive patient-monitoring, but proof is required that new devices can perform biopotential recording with a quality at least comparable to existing medical devices. Aside from electrical safety requirement recommended by standards and concise circuit requirement, there is not yet a complete validation procedure able to demonstrate improved or even equivalent performance of the new devices. This short review discusses the validation procedures presented in recent, landmark literature and offers interesting issues and hints for a more complete assessment of novel biopotential front-end

A Power-Efficient Bio-Potential Acquisition Device with DS-MDE Sensors for Long-Term Healthcare Monitoring Applications

This work describes a power-efficient bio-potential acquisition device for long-term healthcare applications that is implemented using novel microelectromechanical dry electrodes (MDE) and a low power bio-potential processing chip. Using micromachining technology, an attempt is also made to enhance the sensing reliability and stability by fabricating a diamond-shaped MDE (DS-MDE) that has a satisfactory self-stability capability and superior electric conductivity when attached onto skin without any extra skin tissue injury technology. To acquire differential bio-potentials such as ECG signals, the proposed processing chip fabricated in a standard CMOS process has a high common mode rejection ratio (C.M.R.R.) differential amplifier and a 12-bit analog-to-digital converter (ADC). Use of the proposed system and integrate simple peripheral commercial devices can obtain the ECG signal efficiently without additional skin tissue injury and ensure continuous monitoring more than 70 hours with a 400 mAh battery

A fully-differential biopotential amplifier with a reduced number of parts

Objective: Fully differential topologies are wellsuited for biopotential amplifiers, mainly for single-supply battery-powered circuits such as portable wearable devices where a reduced number of parts is desired. A novel fully differential biopotential amplifier is proposed with the goal of providing electrode offset rejection, bandwidth limitation, and a temporal response compliant with biomedical standards with only a single commercial quad operational amplifier (OA) integrated circuit. Methods: A novel compensation strategy was used to provide a transfer function with only one zero at the origin, which makes it easy to comply with the transient response imposed by biomedical standards. A topology with no grounded components was leveraged to obtain a common-mode rejection ratio (CMRR) ideally infinite and independent of components mismatches. Results: Design equations are presented and, as an example, an electrocardiogram (ECG) amplifier was built and tested. It features a CMRR of 102 dB at 50 Hz, 55 dB gain that supports DC input voltages up to ±300 mV when powered from a 0 V to 5 V single-supply voltage, and a cutoff frequency of less than 0.05 Hz with a first order response. Conclusion: A fully-differential biopotential front-end was designed and validated through experimental tests, demonstrating proper operation with only 4 OAs. Significance: The amplifier is intended for board-level design solutions, it can be built with off-the-shelf components that can be selected according to specific needs, such as reduced power consumption, low noise, or proper operation from a low-voltage power source.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

Sistema de medida de sinais eletrofisiológicos utilizando eléctrodos e-textiles embebidos numa cadeira de rodas com localização GPS e RFID

Dissertação de Mestrado em Integração de Sistemas IndustriaisO objetivo deste projeto é desenvolver uma cadeira de rodas inteligente que permita avaliar o estado de saúde do paciente com dificuldades motoras, doenças crónicas ou idade avançada. A partir de informações obtidas em tempo real, que permitam a monitorização dos sinais electrofisiológicos do electrocardiograma (ECG) e da condutividade da pele, de forma a analisar esses parâmetros e acessíveis remotamente a uma central de informação. Este projeto pretende dar apoio às pessoas com mobilidade reduzida de forma a serem monitorizadas nas suas próprias habitações. Os dados monitorizados são analisados em tempo real por um médico, que poderá estar no seu local de trabalho e deslocar-se ou pedir auxilio, para socorrer o mais rapidamente possível o paciente sempre que necessário. Assim, é possível uma mais rápida e atempada intervenção em caso de detecção de anomalias que coloquem em risco a vida do paciente. Alguns dos problemas de saúde em que este projecto se enquadra são doenças crónicas, como por exemplo os diabetes, hipertensão arterial, colesterol, obesidade, problemas cardíacos (enfarte e ataque cardíaco), acidentes vasculares cerebrais (AVC) ou até em casos de idade avançada ou mesmo devido a acidentes. Os sensores de aquisição de sinais são embutidos nos braços de apoio da cadeira de rodas, de modo a que o paciente esteja a ser monitorizado sem se aperceber

Bİyopotansiyel işaretlerin ikinci nesil akım taşıyıcılar ile işlenmesi ve yeni bir EKG devresi tasarımı

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Anahtar kelimeler: CCII, ikinci nesil akım taşıyıcılar, filtre, EKG Bu çalışmada bir EKG cihazı tasarlanmış ve bu cihaz ikinci nesil akım taşıyıcılar ile gerçekleştirilmiştir. Bu EKG devresinde ikinci nesil akım taşıyıcılar filtre olarak kullanılmıştır. Bu cihazın doğruluğunu kontrol edebilmek ve karşılaştırmasını yapabilmek için Sakarya Üniversitesi Elektrik-Elektronik Mühendisliği'ne ait olan BIOPAC Systems Inc. şirketinin imal ettiği MP36 EKG cihazı ile ölçümler eş zamanlı olarak yapılmıştır. Ayrıca OPAMP'larla tasarlanan bir EKG devresi de gerçekleştirilmiş ve sonuçları değerlendirilmiştir. OPAMP'larla gerçekleştirilen bu devre ikinci nesil akım taşıyıcılarla yeniden dizayn edilmiş ve gerçekleştirilerek sonuçları değerlendirilmiştir. Böylece OPAMP'larla gerçekleştirilmiş bir EKG devresi, ikinci nesil akım taşıyıcılarla yeniden dizayn edilmiş bir EKG devresi, bu çalışmada tasarlanmış ve ikinci nesil akım taşıyıcılarla tasarlanmış bir EKG devresi, MP36 devresi ve daha önce literatürde gerçekleştirilmiş EKG devrelerinin kıyaslaması yapılmıştır. Ayrıca biyomedikal cihazlarda sıklıkla kullanılan filtreler, yükselteçler ve bazı devreler simule edilmiştir. CCII tabanlı olan devrede gürültüler minimuma inmiş ve çok net EKG ölçümü yapılabilmiştir. EKG devresi 9,5*9,5 cm2 boyutlarına kadar indirgenebilmiştir. Entegrelerin ve diğer elemanların SMD türlerinin kullanılması ile daha da küçültülebilmesi mümkündür. Gerçeklenen devre maliyet açısından da avantajlıdır. 4 adet kalem pille çalışabilir olması da bir diğer avantajıdır. CMRR oranı, frekans aralığı, yükseltme oranı ve uygulanabilme kolaylığı açısından CCII tabanlı olan EKG devrelerinin daha avantajlı olduğu sonucu ortaya çıkmaktadır. Ayrıca bu çalışmada rezonans frekansını ayarlamak ve daha iyi sonuç elde edebilmek için CCII yapısına ayarlı dirençler eklenmesi sebebiyle 5 Hz ile 100 MHz arasında bir kesim frekansına sahip bir filtre yapısı öne sürüldü ve bu devrede kullanılabilir olduğu gözlemlendi.Keywords: CCII, second generation current conveyors, filter, ECG In this study, an ECG device was designed and this device was carried out with second generation current carriers. Second generation current carriers were used as filters in this ECG circuit. Measurements were simultaneously performed with MP36 ECG device produced by BIOPAC Systems Inc. that is belong to Sakarya University Electrical and Electronics Engineering Department in order to be able to check and compare accuracy of this device. An ECG circuit designed with OPAMPs was also carried out and results were evaluated. This circuit, which was realized with OPAMPs, was redesigned with second generation current carriers and results were evaluated by performing. Thus, an ECG circuit realized with OPAMPs, a redesigned ECG circuit with second generation current carriers were designed in this study, and an ECG circuit with second generation current carriers, MP36 circuit and previous circuits in literature were compared. In addition, filters, amplifiers and some circuits, which are frequently used in biomedical devices are simulated. Noises were reduced to minimum in CCII-based circuit and very clear ECG measurements was done. ECG circuit can be reduced to size of 9.5 * 9.5 cm2. It is possible to further reduce integrals and other elements by use of SMD types. Performed circuit is also advantageous in terms of cost. Another advantage is that it can work with 4 batteries. It was concluded that CCII based ECG circuits are more advantageous in terms of CMRR ratio, frequency range, amplification rate and ease of application. Also, in this study, a filter structure having a cut-off frequency between 5 Hz to 100 MHz was proposed because of adding adjusted resistors to CCII structure to adjust resonance frequency and achieve better results, and it was observed to be usable in this circuit