Development of integrated photoplethysmographic recording circuit for trans-nail pulse-wave monitoring system

Zhengyang Qian, Yoshiki Takezawa, Kenji Shimokawa, Hisashi Kino, Takafumi Fukushima, Koji Kiyoyama, Tetsu Tanaka

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Health monitoring and self-management have become increasingly more important because of health awareness improvement, the aging of population, and other reasons. In general, pulse waves are among the most useful physiological signals that can be used to calculate several parameters such as heart rate and blood pressure for health monitoring and self-management. To realize an automatic and real-time pulse-wave monitoring system that can be used in daily life, we have proposed a trans-nail pulse-wave monitoring system that was placed on the fingernail to detect photoplethysmographic (PPG) signals as pulse waves. In this study, we designed a PPG recording circuit that was composed of a 600 × 600 μm2 photodiode (PD), an LED driver with pulse wave modulation (PWM) and a low-frequency ring oscillator (RING), and a PPG signal readout circuit. The proposed circuit had a very small area of 2.2 × 1.1 mm2 designed with 0.18 μm CMOS technology. The proposed circuit was used to detect pulse waves on the human fingernail in both the reflection and transmission modes. Electrical characteristics of the prototype system were evaluated precisely and PPG waveforms were obtained successfully.

Original languageEnglish
Article number04FM11
JournalJapanese journal of applied physics
Issue number4
Publication statusPublished - 2018 Apr

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)


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