To our engineering teams, the words ‘it cannot be done’ work like a magic charm. They take pride in solving the seemingly impossible. In the interview series ‘Our eureka moment’, engineers talk about these breakthroughs; what challenges did they face and how did they overcome them, together with their colleagues?
Imagine a small biosensor, that sticks to your chest and measures your vital signs – like respiratory rate, heart rate, activity and posture. Designing such a device brings quite some engineering challenges. The signals have to be collected from the skin via a sensor that is only 2 x 3 centimeters, after which signals are shared with the hospital every 5 minutes. Directly, so without the need for a patient to link the sensor to a smartphone or other Bluetooth device. Needless to say, it needs to work always and everywhere.
Electronics Designer Rowanne Steiner was single-handedly responsible for the design of an antenna that made it all possible. What is even more remarkable; she did it while graduating from university.
With a bachelor’s in Biomedical Sciences and a master’s in Electrical Engineering, Rowanne has always been interested in the cross-section of healthcare and technology. “Eventually, I chose electrical engineering, because of the fast technical developments in this area. If you develop an MRI that performs better than the current generation, it can already save lives next year. Biomedical research can take up to 20 to 30 years.”
“I chose electrical engineering, because of the fast technical developments in this area. If you develop an MRI that performs better than the current generation, it can already save lives next year.”
Radio-frequency (RF) antennas is, according to Rowanne, a technical field that brings many appealing elements together: “On one hand, it requires quite some theoretical know-how in physics. At the same time antennas are very tangible. You can design an antenna and incorporate it in a product. Antennas bring devices to the next level – making them connected and smart.”
Her first practical assignment during her studies was in Australia, where she worked with huge kilometers wide antennas that can investigate space: “It was an amazing project, but I missed the medical application. That is how I ended up at Philips Engineering Solutions, in a team that offers RF consultancy.”
Developing a biosensor from initial design to actual production
Philips Engineering Solutions had already been involved with previous generations of the biosensor – from initial design to actual production. The RF consultancy team was asked to advise on the next generation of a biosensor, that is used to monitor patients from a distance. The sensor is placed on the body in the hospital. Patients then can go home and the connected medical wearable transmits signals to the hospital every 5 minutes. “It is very important that it does so directly,” says Rowanne, “so patients don’t need to link the sensor to a mobile app or device.”
Low frequency waves with a small antenna
“It is quite difficult to broadcast low frequency waves with a small antenna. But the biosensor needs to be very small. What’s more, is that the human body tends to absorb a lot of the signals that a sensor sends out.”
With these challenges, Rowanne’s initial task was not to design the actual antenna, but to learn by doing: “My graduation assignment was to develop an antenna in parallel with a supplier, so Philips could acquire that competency for future projects.”
Things worked out differently. Her design outperformed that of the partner and thus made it into the actual product.
What was her eureka moment? “I think it was primarily the research that I did. There is a lot of theoretical knowledge about the balance between antenna size, quality, and frequency range. Larger antennas are more efficient and have a higher range. What I basically did, is calculate how far you can stretch the frequency range and efficiency of an antenna that is only 2 by 3 centimeters.”
Antenna that stretches across the entire PCB
She decided to design an antenna that would stretch across the entire PCB of the biosensor. “The surface of the antenna is the same size as the sensor itself. The quality of the antenna appeared to be surprisingly high; even the first prototype had a performance that was ten times as high as the antenna that our partner designed.”
Less surprisingly, Rowanne was invited to work at Philips Engineering Solutions. After the project, she applied her learnings and experience to enhance other devices with high quality antennas – both within Philips and for external customers. “This ranges from designing new antennas for a mobile electrocardiogram device to antennas for underwater equipment and extremely high frequency antennas for short distances.”
The sensor with Rowannes antenna is now on the verge of conquering Europe: “It is super exciting to see that the sensor is now in the test phase. Not before long, it will be used by thousands of patients. I can still hardly believe it.”
“It is super exciting to see that the sensor is now in the test phase. Not before long, it will be used by thousands of patients. I can still hardly believe it.”