RESUMO
This research is an extension of a previous research [1] on the different effects of sensor location that is relatively suitable for heart rate sensing. This research aimed to elucidate the causes of wide variations in heart rate measurements from the same sensor position among subjects, as observed in previous research [1], and to enhance designs of the inductive textile electrode to overcome these variations. To achieve this, this study comprised two parts: In part 1, X-ray examinations were performed to determine the cause of the wide variations noted in the findings from previous research [1], and we found that at the same sensor position, the heart activity signal differed with slight differences in the positions of the heart of each subject owing to individual differences in the anatomical heart location. In part 2, three types of dual-loop-type textile electrodes were devised to overcome variations in heart location that were confirmed in part 1 of the study. The variations with three types of sensor designs were compared with that with a single-round type of electrode design, by using computer simulation and by performing a t-test on the data obtained from the experiments. We found that the oval-oval shaped, dual-loop-type textile electrode was more suitable than the single round type for determining morphological characteristics as well as for measuring appropriate heart activity signals. Based on these results, the oval-oval, dual-loop-type was a better inductive textile electrode that more effectively overcomes individual differences in heart location during heart activity sensing based on the magnetic-induced conductivity principle.
Assuntos
Vestuário , Eletrodos , Frequência Cardíaca , Coração/anatomia & histologia , Tecnologia de Sensoriamento Remoto/instrumentação , Telemedicina/instrumentação , Simulação por Computador , Desenho de Equipamento , HumanosRESUMO
In the research related to heart rate measurement, few studies have been done using magnetic-induced conductivity sensing methods to measure the heart rate. The aim of this study was to analyze the effect of the position of a textile-based inductive coil sensor on the measurement of the heart rate. In order to assess the capability of the textile-based inductive coil sensor and the repeatability of measured cardiac muscle contractions, we proposed a new quality index based on the morphology of measured signals using a textile-based inductive coil sensor. We initially explored eight potential positions of the inductive sensor in a pilot experiment, followed by three sensor positions in the main experiment. A simultaneously measured electrocardiography (ECG) signal (Lead II) which was used as a reference signal for a comparison of the R-peak location with signals obtained from selected positions of the textile-based inductive coil sensor. The result of the main experiment indicated that the total quality index obtained from the sensor position 'P3', which was located 3 cm away from the left side from the center front line on the chest circumference line, was the highest (QI value = 1.30) among the three positions across all the subjects. This finding led us to conclude that (1) the position of the textile-based inductive coil sensor significantly affected the quality of the measurement results, and that (2) P3 would be the most appropriate position for the textile-based inductive coil sensor for heart rate measurements based on the magnetic-induced conductivity sensing principle.
Assuntos
Eletrocardiografia Ambulatorial/instrumentação , Frequência Cardíaca/fisiologia , Magnetismo/instrumentação , Têxteis , Adulto , Desenho de Equipamento , Humanos , Masculino , Projetos Piloto , Reprodutibilidade dos TestesRESUMO
There are many types of devices which help to manage a personal health conditions such as heartbeat chest belt, pedometer and smart watch. And the most common device has the relationship with heart rate or ECG data. However, users have to attach some electrode or fasten the belt on the bare skin to measure bio-signal information. Therefore, most of people want more convenient and short-ready-time and no-need to attach electrode. In this paper, we proposed the high-resolution measuring system of mechanical activity of cardiac muscle and thereby measure heartbeat. The principle of the proposed measuring method is that the alternating current generate alternating magnetic field around coil. This primary magnetic field induces eddy current which makes magnetic field against primary coil in the nearby objects. To measure high-resolution changes of the induced secondary magnetic fields, we used digital Phase-locked loop(PLL) circuit which provides more high-resolution traces of frequency changes than the previous studies based on digital frequency counter method. As a result of our preliminary experiment, peak-peak intervals of the proposed method showed high correlation with R-R intervals of clinical ECG signals(r=0.9249). Also, from signal traces of the proposed method, we might make a conjecture that the contraction of atrium or ventricle is reflected by changing conductivity of cardiac muscle which is beating ceaselessly.