Office of Technology Transfer – University of Michigan

Epsilon-Tube Filtering for Artifact Reduction in Impedance and Other Physiologic Signal Monitoring

Technology #6115

Recently, mobile healthcare market is growing very fast and attracts considerable interest. Portable monitoring devices are one promising type of mobile healthcare devices. For a portable monitoring device, one significant challenge is to reduce motion artifact (MA). The difficulty of MA reduction results from the dynamic nature of MA and the much larger signal amplitude of MA compared to the signal of interest. The conventional technology for MA reduction, which employs adaptive filters to analyze MA, suffers from the fact that the adaptive filters not only model MA but also adapt to useful signals. It remains a big challenge to maintain useful signals while reducing MA.

A novel technology for MA reduction

This technology employs a novel approach to estimate MA by combining the unique functions and models such that the useful signals won’t be affected during the process. The experimental results show that this technology can lead to more effective MA reduction compared to the conventional approaches. This technology is adaptive for current physiologic signal monitors as well as wearable sensor monitoring.


  • Respiration monitoring
  • Invasive and noninvasive blood pressure and arterial vascular wall stiffness monitoring
  • Photoplethymograph monitoring
  • ECG monitoring
  • Intracranial pressure monitoring


  • adaptive for current physiologic signal monitors
  • adaptive for wearable sensor monitoring