This paper describes a pulse wave sensing textile to measure pulse wave continuously without stress. Due to aging population, the attention is focused on measurement of vital signs during daily life. Blood pressure (BP) is widely used as an index representing the state of the circulatory system. BP can be estimated from electrocardiogram (ECG) and photoplethysmogram (PPG). PPG can be obtained by a combination of a light emitting diode (LED) and a phototransistor (PT). The textile measured PPG has not been realized although there are fabric electrodes for measuring ECG. Therefore we developed the pulse wave sensing textile for using underwear aiming to continuously BP estimation. By using conductive fibers woven into the textile as wiring, the pulse wave sensing textile is realized. In order to improve the stability of pulse wave measurement, LEDs and PTs were arranged in array on the textile. We designed the textile circuit under the consideration that circuit lines on the textile must be straight. We showed that arranging LEDs and PTs in an array improve the stability of pulse detection and evaluated that the proposed sensing textile can be measured pulse wave on the waist even if a person attached the proposed sensing textile is moving. These results suggest that the proposed sensing textile could be built into underwear and used as a part of BP estimation system. Unconscious continuous BP monitoring underwear could be realized by combining the proposed textile with fabric electrodes.
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