Detecting Blood Pressure With RADAR

Infineon and Blumio have teamed up to develop a non-invasive radar-based blood pressure sensor that allows for continuous blood pressure monitoring. How do traditional blood pressure monitors work, what does radar do differently, and how will it enable wearable devices?

Blood Pressure Monitoring

As many health conditions are related to blood pressure, the ability to measure blood pressure in the medical field is essential. While there are different methods for measuring pressure, non-invasive methods (i.e. those that don’t penetrate the skin), require constriction of a limb to prevent the flow of blood through an artery before releasing the pressure to detect when blood flow starts. This method is perfectly adequate for hospital and home environments where pressure readings are only required once every so often. However, such technology cannot be used on-the-go, meaning that a continuous monitoring device is not possible. Therefore, constriction-based methods cannot be used in wearable devices which is problematic when considering the advantages provided by blood pressure monitoring. One method that has been researched into is the use of radio signals; a transmitter is placed on one part of the body while the receiver is placed in another location. Radio signals sent by the transmitter can be detected by the receiver, and the effect on the signal is observed to determine blood pressure. However, this technology only exists in the lab and is yet to be commercialised, until now. 

Introducing Radar-Based Measurements

Realising the potential impact on the blood pressure industry, Infineon and Blumio have teamed up to work on producing blood pressure monitor sensors utilising the radar method. The new blood pressure sensors will be based on Infineon’s XENSIV radar chipset operating on the 60GHz range. Radar technologies have some major advantages over other technologies, including the ability to be cuff-less (which can be uncomfortable), and provide continuous readings of blood pressure.

While not much information has been released as to how the sensor works a report in February 2020 describes how a team of researchers were able to utilise radar technologies to monitor blood pressure. According to the report, a small radar emitter is externally connected to the sternum (flat plate between the ribs), while a photoplethysmogram receiver is connected to the earlobe. The blood pressure is calculated by combining pulse arrival time (PAT), pre-ejection period (PEP), and pulse transient time (PTT). To further refine the results, multiple subjects were observed in different states (i.e. resting, exercising etc.), and the combined data provided a sensor that could provide a best cumulative error percentage of 92.28%. 

Infineon and Blumio hope to disrupt the estimated $45 billion market with their blood pressure sensor that will help to further improve medical wearable devices. Such devices could potentially help to prevent blood pressure-related conditions, and provide wearers with an early warning system to heart attacks and strokes.

“We are thrilled to work together with Infineon, the technology leader in radar, to jointly bring the new blood pressure sensor to market. We have experienced tremendous support since the beginning of our partnership in 2018 and we look forward to further advance our collaboration with Infineon.” 

• Catherine Liao, Co-founder and CEO of Blumio

Conclusion

Wearable devices have a long way to go, and a wearable device that requires a sensor attached to the sternum may not be entirely comfortable. However, as technology progresses, wearable devices will become more comfortable to wear while providing more information on the wearer. Just like diabetes socks, a continuous blood pressure monitoring system will certainly transform the medical field.