Electrical Impedance Tomography (EIT)


Electrical current can pass through the human body since it consists of conductive biological tissues and fluids.  Inhalation increases electrical resistance or impedance of the lung tissue because the increasing air volume further impedes current flow.  This increased impedance induces higher voltage inside the body.

When a high-frequency current is injected into the chest through surface electrodes, the induced voltage changes with lung ventilation and cardiac blood flow. Electrical impedance tomography (EIT) utilizes these voltage changes to produce cross-sectional images of lung ventilation and cardiac blood flow.

Unlike the ionizing radiation of X-rays, EIT is safe. The amount of injected currents is below the safety limit specified in the international standard. Whereas other imaging modalities of CT, MRI, and ultrasound produce structural images, EIT produces functional images to monitor lung ventilation and hemodynamics.

BiLab’s EIT platform technology offers

  • Cross-sectional time-difference imaging of tissue conductivity
  • Noninvasive continuous bedside imaging and monitoring
  • Quantitation of clinical information such as tidal volume, minute ventilation, stroke volume, cardiac output, etc.


  1. Oh T I, Woo E J and Holder D 2007 Multi-frequency EIT system with radially symmetric architecture: KHU Mark1 Physiol. Meas. 28 S183-S196
  2. Oh T I, Lee K H, Kim S M, Koo H, Woo E J and Holder D 2007 Calibration methods for a multi-frequency EIT system Physiol. Meas. 281175-1188
  3. Oh T I, Koo H, Lee K H, Kim S M, Lee J, Kim S W, Seo J K and Woo E J 2008 Validation of a multi-frequency electrical impedance tomography (mfEIT) system KHU Mark1: impedance spectroscopy and time-difference imaging Physiol. Meas. 29 295-307
  4. Kuen J, Woo E J and Seo J K 2009 Multi-frequency time-difference complex conductivity imaging of canine and human lungs using the KHU Mark1 EIT system Physiol. Meas. 30 S149-64
  5. Oh T I, Wi H, Kim D Y, Yoo P J and Woo E J 2011 A fully parallel multi-frequency EIT system with flexible electrode configuration: KHU Mark2 Physiol. Meas. 32 835-49
  6. Oh T I, Kim T E, Yoon S, Kim K J, Woo E J and Sadleir R J 2012 Flexible electrode belt for EIT using nanofiber web dry electrodes Physiol. Meas. 33 1603-16
  7. Oh T I, Yoon S, Kim T E, Wi H, Kim K J, Woo E J and Sadleir R J 2013 Nanofiber web textile dry electrode for long-term biopotential recording IEEE Trans. Biomed. Circ. Sys. 7 204-211
  8. Sohal H, Wi H, McEwan A L, Woo E J and Oh T I Electrical impedance imaging system using FPGAs for flexibility and interoperability 2014 Biomed. Eng. OnLine 13 126

AirTom-R is a 16-channel electrical impedance tomography (EIT) system with 100 frames per second temporal resolution. It is approved by the Ministry of Food and Drug Safety (MFDS) in Korea. AirTom-R can be used by healthcare professionals in healthcare facilities for lung volume measurements. AirTom-R can also be used as a research tool for numerous clinical applications of the EIT technology.

Case Study 1 : Tidal Volume Measurements of Mechanically Ventilated Swine Lungs using EIT

Case Study 2 : Simultaneous Tidal Volume Measurements using Spirometer and EIT

Case Study 3 : EIT Imaging of Mechanically Ventilated Swine Lungs

Case Study 4 : Optimal PEEP for Lung Protective Ventilation of Swine Lungs using EIT