Integrated circuits and electrode interfaces for noninvasive physiological monitoring

Sohmyung Ha, Chul Kim, Yu M. Chi, Abraham Akinin, Christoph Maier, Akinori Ueno, Gert Cauwenberghs

Research output: Contribution to journalArticlepeer-review


This paper presents an overview of the fundamentals and state of the-art in noninvasive physiological monitoring instrumentation with a focus on electrode and optrode interfaces to the body, and micropower-integrated circuit design for unobtrusive wearable applications. Since the electrode/optrode-body interface is a performance limiting factor in noninvasive monitoring systems, practical interface configurations are offered for biopotential acquisition, electrode-tissue impedance measurement, and optical biosignal sensing. A systematic approach to instrumentation amplifier (IA) design using CMOS transistors operating in weak inversion is shown to offer high energy and noise efficiency. Practical methodologies to obviate 1/f noise, counteract electrode offset drift, improve common-mode rejection ratio, and obtain subhertz high-pass cutoff are illustrated with a survey of the state-of-the-art IAs. Furthermore, fundamental principles and state-of-the-art technologies for electrode-tissue impedance measurement, photoplethysmography, functional near-infrared spectroscopy, and signal coding and quantization are reviewed, with additional guidelines for overall power management including wireless transmission. Examples are presented of practical dry-contact and noncontact cardiac, respiratory, muscle and brain monitoring systems, and their clinical applications.

Original languageEnglish (US)
Article number6748876
Pages (from-to)1522-1537
Number of pages16
JournalIEEE Transactions on Biomedical Engineering
Issue number5
StatePublished - May 2014


  • Biological signal sensing
  • biomedical electronics
  • body-electrode interface
  • electrode contacts
  • electrode-tissue impedance
  • functional near-infrared spectroscopy
  • health monitoring
  • instrumentation amplifier (IA)
  • optrode interface
  • photoplethysmography
  • sensor interface

ASJC Scopus subject areas

  • Biomedical Engineering


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