Wearable Water Content Sensor Based on Ultrasound and Magnetic Sensing

Song Zhang, Rajesh Rajamani, A. Serdar Sezen

Research output: Contribution to journalArticlepeer-review


Fluid accumulation in the lower extremities is an early indicator of disease deterioration in cardiac failure, chronic venous insufficiency and lymphedema. At-home wearable monitoring and early detection of fluid accumulation can potentially lead to prompt medical intervention and avoidance of hospitalization. Current methods of fluid accumulation monitoring either suffer from lack of specificity and sensitivity or are invasive and cost-prohibitive to use on a daily basis. Ultrasound velocity in animal and human tissue has been found to change with water content. However, previous prototype fluid monitoring sensors based on ultrasound are cumbersome and not wearable. Hence, in this research a compact water content sensor based on a wearable instrumented elastic band is proposed. A novel integration of magnetic sensing and ultrasonic sensing is utilized, where the magnetic sensor provides distance measurement and the ultrasonic sensor produces time-of-flight measurement. Magnetic field modeling with a Kalman filter and least squares linear fitting algorithms are employed to ensure robust sensor performance on a wearable device. The combination of the two measurements yields ultrasound velocity measurement in tissue. The water content sensor prototype was tested on a tissue phantom, on animal tissue and on a human leg. The error in velocity measurement is shown to be small enough for early detection of tissue edema.

Original languageEnglish (US)
Pages (from-to)2079-2090
Number of pages12
JournalAnnals of Biomedical Engineering
Issue number12
StatePublished - Dec 15 2018


  • Fluid accumulation
  • Human volunteer tests
  • Kalman filters
  • Magnetic field modeling
  • Magnetic sensing
  • Ultrasound time-of-flight
  • Water content

Fingerprint Dive into the research topics of 'Wearable Water Content Sensor Based on Ultrasound and Magnetic Sensing'. Together they form a unique fingerprint.

Cite this