Filter4Flow – A smart, non-invasive respiratory filter system

Monitoring breathing close to the patient: Precise, wireless and intuitive


As part of the Filter4Flow project, we are working on a novel technology for monitoring patients’ breathing. It improves clinical treatment processes, allows respiratory parameters to be recorded close to the patient and can be used outside the ICU.
Our smart virus filter revolutionizes respiratory monitoring for patients suffering from conditions such as SARS-CoV-2 by filtering out harmful particles from the air while also continuously monitoring all relevant parameters (breathing flow, oxygen level, tidal volume, etc.). This means that patients can be given ideal respiratory assistance at all times. The design allows filters and sensors to be replaced quickly and easily, thus making life easier for the nursing staff. The simplicity of the application means that it can even be used outside medical institutions, for example in developing countries or crisis regions.


The sensor and electronic components responsible for measuring respiratory mechanism values tend to be located in hard-to-reach places inside ventilators. This distance from the patient is enough to distort results and makes it harder to replace individual components as required. Continuous respiratory monitoring is relevant for all patient groups, whether or not pneumonia has been diagnosed. But up to now, this kind of monitoring has been possible only in the ICU, where it is managed by specially trained personnel.

Immediate diagnosis close to the patient

Our Solution

Made of thin fabric, the smart respiratory system’s filter is positioned directly between the ventilator hose and the patient’s breathing tube. Sensor elements such as strain gauge strips and gas sensors are attached to the fabric to allow for point-of-care recording of respiratory activity and gas concentrations.
The filter-sensor combination protects patients from viruses and bacteria while wireless signal transmission makes it easier to manage their respiratory assistance. Since the respiratory filter system can be replaced quickly and easily, it makes life easier for the nursing staff.

Added value of the robust respiratory filter system

  • Non-invasive, point-of-care recording of relevant respiratory parameters (breathing flow, air pressure, oxygen level)
  • Maintenance-free and cost-effective single-use item
  • Good accessibility and ease of use enable non-hospital use (developing countries, crisis regions)
  • Hygienic thanks to the straightforward exchange of individual components

Current situation

  • An initial lab prototype of the proposed measuring system is ready and comprises strain gauge strips, amplifier boards and control devices.
  • The prototype is undergoing a proof-of-concept test.
  • Further miniaturization of the sensor elements and refinement of the SGS structures is scheduled to take place in early 2021.   

Project Partner

The following Fraunhofer institutes are involved in the Filter4Flow project:

  • Fraunhofer IIS
  • Fraunhofer ITEM
  • Fraunhofer IST