Biosignals sensing by novel use of bidirectional microphones in a mobile phone for ubiquitous healthcare monitoring

Kajiro Watanabe, Yosuke Kurihara, Ko Watanabe, Toshihiro Azami, Shoko Nukaya, Hiroshi Tanaka

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


This paper describes a novel application of the bidirectional audio microphones in mobile phones to measure biosignals for ubiquitous health monitoring. The bidirectional microphone has two pressure-detecting ports. A pressure-detecting film receives the differential pressure between the ports. We apply this idea to biosignal measurements for a mobile phone. We used the microphone as 1) a sphygmograph at the fingertip, 2) a stethoscope in which a delay time sensor of pulse wave arrivals from the neck near the carotid or chest near the heart to the fingertip, and 3) a bed sensing device for biosignals. When used as a sphygmograph, it detects the wave similar to the second derivative of the conventional optical pulse oxymeter output wave. When used as a stethoscope, it detects cardiac sound and the pulse wave and respiration. With two microphones, the delay time from the neck carotid to the fingertip is detected.

Original languageEnglish
Article number6844849
Pages (from-to)545-550
Number of pages6
JournalIEEE Transactions on Human-Machine Systems
Issue number4
Publication statusPublished - 2014 Aug


  • Bidirectional microphone
  • low-frequency microphone
  • mobile phone
  • noninvasive bed sensing
  • sphygmograph
  • stethoscope

ASJC Scopus subject areas

  • Human Factors and Ergonomics
  • Control and Systems Engineering
  • Signal Processing
  • Human-Computer Interaction
  • Computer Science Applications
  • Computer Networks and Communications
  • Artificial Intelligence


Dive into the research topics of 'Biosignals sensing by novel use of bidirectional microphones in a mobile phone for ubiquitous healthcare monitoring'. Together they form a unique fingerprint.

Cite this