Verification and comparison of MIT-BIH arrhythmia database based on number of beats

The ECG signal processing methods are tested and evaluated based on many databases. The most ECG database used for many researchers is the MIT-BIH arrhythmia database. The QRS-detection algorithms are essential for ECG analyses to detect the beats for the ECG signal. There is no standard number of beats for this database that are used from numerous researches. Different beat numbers are calculated for the researchers depending on the difference in understanding the annotation file. In this paper, the beat numbers for existing methods are studied and compared to find the correct beat number that should be used. We propose a simple function to standardize the beats number for any ECG PhysioNet database to improve the waveform database toolbox (WFDB) for the MATLAB program. This function is based on the annotation's description from the databases and can be added to the Toolbox. The function is removed the non-beats annotation without any errors. The results show a high percentage of 71% from the reviewed methods used an incorrect number of beats for this database

Low Power Circuits for Smart Flexible ECG Sensors

Cardiovascular diseases (CVDs) are the world leading cause of death. In-home heart condition monitoring effectively reduced the CVD patient hospitalization rate. Flexible electrocardiogram (ECG) sensor provides an affordable, convenient and comfortable in-home monitoring solution. The three critical building blocks of the ECG sensor i.e., analog frontend (AFE), QRS detector, and cardiac arrhythmia classifier (CAC), are studied in this research. A fully differential difference amplifier (FDDA) based AFE that employs DC-coupled input stage increases the input impedance and improves CMRR. A parasitic capacitor reuse technique is proposed to improve the noise/area efficiency and CMRR. An on-body DC bias scheme is introduced to deal with the input DC offset. Implemented in 0.35m CMOS process with an area of 0.405mm2, the proposed AFE consumes 0.9W at 1.8V and shows excellent noise effective factor of 2.55, and CMRR of 76dB. Experiment shows the proposed AFE not only picks up clean ECG signal with electrodes placed as close as 2cm under both resting and walking conditions, but also obtains the distinct -wave after eye blink from EEG recording. A personalized QRS detection algorithm is proposed to achieve an average positive prediction rate of 99.39% and sensitivity rate of 99.21%. The user-specific template avoids the complicate models and parameters used in existing algorithms while covers most situations for practical applications. The detection is based on the comparison of the correlation coefficient of the user-specific template with the ECG segment under detection. The proposed one-target clustering reduced the required loops. A continuous-in-time discrete-in-amplitude (CTDA) artificial neural network (ANN) based CAC is proposed for the smart ECG sensor. The proposed CAC achieves over 98% classification accuracy for 4 types of beats defined by AAMI (Association for the Advancement of Medical Instrumentation). The CTDA scheme significantly reduces the input sample numbers and simplifies the sample representation to one bit. Thus, the number of arithmetic operations and the ANN structure are greatly simplified. The proposed CAC is verified by FPGA and implemented in 0.18m CMOS process. Simulation results show it can operate at clock frequencies from 10KHz to 50MHz. Average power for the patient with 75bpm heart rate is 13.34W

심전도 감시 분야를 위한 저전력 신호 특화된 축차 비교형 아날로그-디지털 변환기의 설계

학위논문 (박사)-- 서울대학교 대학원 공과대학 전기·컴퓨터공학부, 2017. 8. 김수환.Electrocardiography is an indispensable tool employed for diagnosis of cardiovascular diseases. When electrocardiograms (ECGs) need to be monitored for a long time, e.g. to diagnose arrhythmia, a device has to be worn or implanted under the skin, which requires low energy consumption. Successive approximation register analog-to-digital converters (SAR ADCs) have been especially preferred in low power applications, while the recent trend of ADC designs shows that the SAR ADCs find a much wide range of applications, and are the most versatile ADC architecture. The subject of the dissertation is the design of a signal-specific SAR ADC scheme that reduces the power consumption by exploiting the characteristics of the input signal of a particular type whose signal activity is low on average and dichotomous, as best exemplified by ECGs. This dissertation presents a 1.8-V 10-bit 1-kS/s low-power SAR ADC with the proposed signal-specific switching algorithm. The proposed adaptive switching algorithm has two operation modes suitable for the dichotomous activity of the ECG: full switching mode that resolves the full range of the input as an ordinary SAR ADC, and reduced switching mode that assumes 5 MSBs will not change and samples just the rest LSB portion and resolves it in 5 bitcycles. The reduced number of bitcycles yields saving in switching power consumption. For smooth mode change adaptive to the input signal activity, an additional function in each mode, viz., MSBs tracking in full switching mode and LSBs extrapolation in reduced switching mode, runs concurrently with the respective main operation. A behavioral model of the proposed SAR ADC with the segmented capacitor digital-to-analog converter (CDAC) topology was created in MATLAB and was used in the tests, which verified the function and effectiveness of the adaptive switching algorithm. The model describes the evolution of all internal node voltages in the CDAC by each switching action, from which the charge variation in each capacitor and the switching energy consumption can be computed. The model was extensively used for the development and analysis of the idea. The 5-bit size of the MSB section was determined from the simulation results with the behavioral model. A prototype chip was fabricated in 0.18-μm CMOS technology. Measurements with an ECG type input proved the suitability of the adaptive switching for ECG monitoring. The power reduction by the adaptive switching in each of comparator, logic, and DAC power domains was calculated from the measurements of both cases of the adaptive-switching and fixed-full-switching operations, the latter of which is equivalent to the conventional SAR ADC operation. It achieved a reduction in comparator power consumption by 39%. The DAC power, i.e. the switching power consumed in the CDAC, achieved a reduction by 1.28 nW, which is close to the result of the behavioral model simulation. The reduction in the logic power domain was 12%. In terms of total power consumption, the adaptive switching consumed 91.02 nW while the fixed full switching consumed 107.51 nW. The reduction corresponds to 15.3% in proportion. In addition, the intrinsic performance of the ADC was measured using a sinusoidal input. It achieved a signal-to-noise-and-distortion ratio of 56.24 dB and a spurious-free dynamic range of 62.00 dB. The maximum differential nonlinearity of +0.39/−1 LSBs and maximum integral nonlinearity of +0.86/−1.5 LSBs were measured. The main source of the nonlinearity is the capacitor mismatch in the CDAC.심전도는 심혈관계 질환의 진단을 위한 중요한 자료로서 감시 및 기록된다. 때로 부정맥 진단 등을 위하여 심전도를 오랜 시간 관찰해야 할 경우, 착용 가능한(웨어러블) 장비나 체내에 이식할 수 있는 장비를 사용해야 하는데, 이들은 전력 소비가 적어야 한다. 축차 비교형 아날로그-디지털 변환기(SAR ADC)는 저전력 응용 분야에서 주로 선호한 구조였으나 최근 아날로그-디지털 변환기 설계의 추세는 SAR ADC가 훨씬 넓은 응용 분야에 적용 가능하며 가장 넓은 범용성을 가진 구조임을 보여준다. 본 논문의 주제는 심전도 신호처럼 양분된 신호 활성도를 가지면서 평균 신호 활성도는 낮은 유형의 신호를 대상으로, 이 특성을 이용하여 전력의 소비를 낮추는 신호 특화된 스위칭 기법을 적용한 SAR ADC 설계이다. 본 논문에서는 신호 특화된 기법을 적용한 1.8V, 10 bit, 1kS/s의 저전력 SAR ADC 설계를 제시한다. 제안하는 적응형 스위칭 기법은 ECG의 양분된 신호 활성도 특성에 맞추어, 일반적인 SAR ADC처럼 입력의 전체 범위를 처리하는 full switching mode와, 5-bit MSB code가 변하지 않을 것이라는 가정하에 나머지 LSB 부분만 샘플링하고 처리하는 reduced switching mode의 두 가지 동작 모드를 가진다. 입력 신호 활성도에 따라 유연하게 동작 모드를 전환하기 위하여, full switching mode는 MSBs tracking, reduced switching mode는 LSBs extrapolation라는 부가 기능이 각 모드의 주 기능과 함께 동작한다. 제안한 SAR ADC의 behavioral model을 MATLAB에서 만들었고, 이를 이용한 여러 테스트에서 적응형 스위칭 기법의 기능과 효과를 검증하였다. 이 behavioral model은 SAR ADC 내에 있는 segmented CDAC의 모든 내부 node 전압의 변화를 개별 스위칭 동작에 대해 기술하므로, 이를 이용하여 각 캐패시터에 저장된 전하의 변화량이나 스위칭 에너지 소비량을 계산할 수 있다. 이 model을 idea 개발 및 분석에 광범위하게 이용하였다. 0.18μm CMOS 공정에서 시제품 칩을 제작하였다. 심전도 유형의 입력 신호를 이용한 측정을 통해 제안한 적응형 스위칭 기법이 심전도 감시 분야에 적합함을 증명하였다. 제안한 기법으로 얻어지는 ADC의 전력 감소는 제안한 적응형 스위칭으로 동작한 경우와 full switching mode로 고정된 경우(기존의 SAR ADC 동작에 해당)에서 비교기, 논리 회로, DAC 3개 영역의 전력 측정값에서 계산하였다. 비교기 회로의 전력 소비는 39% 줄었다. DAC에서 소비된 전력, 즉 CDAC의 switching 전력 소비량은 1.28 nW가 감소했는데, behavioral model의 simulation 결과와 비슷한 값이다. 논리 회로 영역에서는 12%가 줄었다. 전체 전력 소비는 적응형 스위칭 기법을 적용했을 때 91.02 nW, full switching mode로 고정했을 때 107.51 nW으로 15.3% 감소하였다. 또, sine 입력을 이용하여 설계한 ADC의 기본 성능을 측정하였다. 그 결과 56.24dB의 SNDR과 62.00 dB의 SFDR을 얻었고, 비선형성 지표인 최대 DNL과 INL은 각각 +0.39/−1 LSBs와 +0.86/−1.5 LSBs 을 얻었다. 이 비선형성 특성은 주로 CDAC 내의 캐패시터 미스매치에 기인한 것이다.Chapter 1 Introduction 1 1.1 Electrocardiography 1 1.2 Recent Trends in SAR ADC Designs 4 1.3 Dissertation Contributions and Organization 7 Chapter 2 SAR ADC Operation and Design Issues 9 2.1 Operation Principle 9 2.2 Switching Algorithms for Power Reduction 12 2.2.1 Computation of Switching Energy Consumption 12 2.2.2 Conventional Charge-Redistribution Switching 15 2.2.3 Split-Capacitor Switching 16 2.2.4 Energy-Saving Switching 18 2.2.5 Set-and-Down Switching 21 2.2.6 Merged-Capacitor Switching 22 2.3 Offset and Noise 25 2.4 Linearity 29 2.5 Area 32 Chapter 3 Adaptive Switching SAR ADC for ECG Monitoring Applications 34 3.1 ECG Characteristics and Readout Circuit 34 3.1.1 ECG Signals and Characteristics 34 3.1.2 ECG Readout Circuit 35 3.2 Related Signal-Specific Works 37 3.2.1 SAR ADC with a Bypass Window for Neural Signals 37 3.2.2 LSB-First Successive Approximation 39 3.3 Adaptive Switching 41 3.3.1 Motivation 41 3.3.2 Preliminary Test 42 3.3.3 Algorithm 46 3.3.4 Energy Consumption of SAR ADC with Segmented CDAC 54 3.3.5 Behavioral Model Simulations 59 3.3.6 Consideration on Other Applications 75 3.4 Circuit Implementation 76 3.4.1 Overview 76 3.4.2 Comparator and CDAC 78 3.4.3 Adaptive Switching Logic 81 Chapter 4 Prototype Measurements 86 4.1 Fabrication and Experiment Setup 86 4.2 Measurements 88 4.2.1 Power Reduction Measurement with ECG-Type Input 88 4.2.2 Intrinsic Performance Measurement with Sinusoidal Input 93 4.2.3 Summary of the Measurements and Specifications 96 Chapter 5 Conclusion 98 Bibliography 101 Abstract in Korean 107Docto

Charakterisierung funktionaler Nanomaterialien für biomagnetische Sensoren und Atemanalyse

The presented thesis is covering materials aspects for the development of magnetoelectric sensors for biomagnetic sensing and solid state sensors for breath monitoring. The electrophysiological signals of the human body and especially their irregularities provide extremely valuable information about the heart, brain or nerve malfunction in medical diagnostics. Similar and even more detailed information is contained in the generated biomagnetic fields which measurement offers improved diagnostics and treatment of the patients. A new type of room temperature operable magnetoelectric composite sensors is developed in the framework of the CRC1261 Magnetoelectric Sensors: From Composite Materials to Biomagnetic Diagnostics. This thesis focuses on the individual materials structure-property relations and their combination in magnetoelectric composite sensors studied by electron beam based techniques, at lengths scales ranging from micrometers to atomic resolution. The first part of this thesis highlights selected studies on the structural and analytic aspects of single phase materials and their composites using TEM as the primary method of investigation. With respect to the piezoelectric phase, alternatives to AlN have been thoroughly investigated to seek for improvement of specific sensor approaches. In this context, the alloying of Sc into the AlN matrix has been demonstrated to yield high quality films with improved piezoelectric and unprecedented ferroelectric properties grown under the control of deposition parameters. Lead-free titanate films with large piezo-coefficients at the verge of the morphotropic phase boundary as alternative to PZT films have been investigated in terms of crystal symmetry, defect structure and domains of cation ordering. New morphologies of ZnO and GaN semiconductors envisioned for a piezotronic-based sensor approach were subject of in-depth defect and analytical studies describing intrinsic defects and lattice strains upon deposition as well as hollow composite structures. When the dimensions of a materials are reduced, novel exciting properties such as in-plane piezoelectricity can arise in planar transition-metal dichalcogenides. Here, the turbostratic disorder in a few-layered MoSe2 film has been investigated by nanobeam electron diffraction and Fast Fourier Transformations. From the perspective of magnetic materials, the atomic structure of magnetostrictive multilayers of FeCo/TiN showing stability up to elevated temperatures has been analyzed in detail regarding the crystallographic relationship of heteroepitaxy in multilayer composites exhibiting individual layer thicknesses below 1 nm. Further, magnetic hard layers have been investigated in the context of exchange spring concepts and ME composites based on shape memory alloy substrates have been studied regarding structural changes implied by different annealing processes. The second part of this thesis introduces materials aspects and sensor studies on gas detection in the clinical context of breath analysis. The detection of specific vapors in the human breath is of medical relevance, since certain species can be enriched depending on the conditions and processes within the human body. Hence, they can be regarded as biomarkers for the patients condition of health. The selection of suitable materials and the gas measurement working principle are considered and selected studies on solid state sensors with different surface functionalization or targeted application on basis of ZnO or CuO-oxide and Fe-oxide species are presented

Libro de actas. XXXV Congreso Anual de la Sociedad Española de Ingeniería Biomédica

596 p.CASEIB2017 vuelve a ser el foro de referencia a nivel nacional para el intercambio científico de conocimiento, experiencias y promoción de la I D i en Ingeniería Biomédica. Un punto de encuentro de científicos, profesionales de la industria, ingenieros biomédicos y profesionales clínicos interesados en las últimas novedades en investigación, educación y aplicación industrial y clínica de la ingeniería biomédica. En la presente edición, más de 160 trabajos de alto nivel científico serán presentados en áreas relevantes de la ingeniería biomédica, tales como: procesado de señal e imagen, instrumentación biomédica, telemedicina, modelado de sistemas biomédicos, sistemas inteligentes y sensores, robótica, planificación y simulación quirúrgica, biofotónica y biomateriales. Cabe destacar las sesiones dedicadas a la competición por el Premio José María Ferrero Corral, y la sesión de competición de alumnos de Grado en Ingeniería biomédica, que persiguen fomentar la participación de jóvenes estudiantes e investigadores

Друга міжнародна конференція зі сталого майбутнього: екологічні, технологічні, соціальні та економічні питання (ICSF 2021). Кривий Ріг, Україна, 19-21 травня 2021 року

Second International Conference on Sustainable Futures: Environmental, Technological, Social and Economic Matters (ICSF 2021). Kryvyi Rih, Ukraine, May 19-21, 2021.Друга міжнародна конференція зі сталого майбутнього: екологічні, технологічні, соціальні та економічні питання (ICSF 2021). Кривий Ріг, Україна, 19-21 травня 2021 року

A Systematic Review and Meta-Analysis of the Incidence of Injury in Professional Female Soccer

The epidemiology of injury in male professional football is well documented and has been used as a basis to monitor injury trends and implement injury prevention strategies. There are no systematic reviews that have investigated injury incidence in women’s professional football. Therefore, the extent of injury burden in women’s professional football remains unknown. PURPOSE: The primary aim of this study was to calculate an overall incidence rate of injury in senior female professional soccer. The secondary aims were to provide an incidence rate for training and match play. METHODS: PubMed, Discover, EBSCO, Embase and ScienceDirect electronic databases were searched from inception to September 2018. Two reviewers independently assessed study quality using the Strengthening the Reporting of Observational Studies in Epidemiology statement using a 22-item STROBE checklist. Seven prospective studies (n=1137 professional players) were combined in a pooled analysis of injury incidence using a mixed effects model. Heterogeneity was evaluated using the Cochrane Q statistic and I2. RESULTS: The epidemiological incidence proportion over one season was 0.62 (95% CI 0.59 - 0.64). Mean total incidence of injury was 3.15 (95% CI 1.54 - 4.75) injuries per 1000 hours. The mean incidence of injury during match play was 10.72 (95% CI 9.11 - 12.33) and during training was 2.21 (95% CI 0.96 - 3.45). Data analysis found a significant level of heterogeneity (total Incidence, X2 = 16.57 P < 0.05; I2 = 63.8%) and during subsequent sub group analyses in those studies reviewed (match incidence, X2 = 76.4 (d.f. = 7), P <0.05; I2 = 90.8%, training incidence, X2 = 16.97 (d.f. = 7), P < 0.05; I2 = 58.8%). Appraisal of the study methodologies revealed inconsistency in the use of injury terminology, data collection procedures and calculation of exposure by researchers. Such inconsistencies likely contribute to the large variance in the incidence and prevalence of injury reported. CONCLUSIONS: The estimated risk of sustaining at least one injury over one football season is 62%. Continued reporting of heterogeneous results in population samples limits meaningful comparison of studies. Standardising the criteria used to attribute injury and activity coupled with more accurate methods of calculating exposure will overcome such limitations