Capacitively Coupled Electrode Array Sensors for Body Posture and ECG Measurement During Sleep

Holter electrocardiographs, which are commonly used for long-term electrocardiographic measurements, are not necessarily suitable for long-term measurements during sleep because the electrodes are directly attached to the skin, causing discomfort and constraint feelings. To handle this problem, electrocardiogram measurement using capacitively coupled electrodes, which do not require direct skin contact, could be an alternative. However, this method requires precise positioning of the electrodes on specific parts of the body, which makes it difficult to work robustly in response to physical body differences and postural variations such as turning over. Therefore, the authors have been working on the realization of a novel electrocardiogram measurement system using capacitively coupled electrodes arranged in an array. The major feature of this system is the ability to measure both body posture and electrocardiogram with common electrodes arranged in an array, and by selecting the most effective electrodes based on the measured posture, it can make electrocardiogram measurements corresponding to the posture changes. In this paper, as the core of the system, a new sensor that can measure both body posture and electrocardiogram with common arrayed electrodes has been designed and implemented. From the experimental results, it was confirmed that the subject’s posture on the electrode array could be obtained from the distribution of capacitance, and also the electrocardiogram of the subject could be obtained with the same electrodes as well.