Scientists at Osaka University, in collaboration with Joanneum Research in Weiz, Austria, have unveiled wireless health monitoring patches that utilize embedded piezoelectric nanogenerators to self-power using harvested biomechanical energy. This breakthrough could pave the way for new autonomous health sensors and battery-less wearable electronic devices.

As wearable technology and smart sensors become increasingly prevalent, powering these devices remains a significant challenge. Despite the modest energy requirements of individual components, the reliance on wires or batteries can be cumbersome and inconvenient. Hence, innovative energy harvesting methods are essential. Additionally, health monitors that can power and activate sensors using ambient motion will likely see faster adoption in medical settings.

The international research team has developed ultraflexible patches featuring a ferroelectric polymer that can sense a patient’s pulse and blood pressure while powering themselves from normal movements. The key innovation was using a substrate only 1-μm thick.

By aligning ferroelectric crystalline domains in a copolymer with a strong electric field, the researchers created a sample with a significant electric dipole moment. Leveraging the piezoelectric effect, which efficiently converts natural motion into small electric voltages, the device responds quickly to strain or pressure changes. These voltages can then be used to power medical sensors or directly harvest energy.

“Our e-health patches may be employed as part of screening for lifestyle-related diseases such as heart disorders, signs of stress, and sleep apnea,” said Andreas Petritz, the first author of the paper.

The researchers estimate that multilayer patches can harvest up to 200 mJ per day from biomechanical motions when placed on joints like knees or elbows. This energy is sufficient to monitor cardiovascular parameters several times a day. The patches’ ultrathin design makes them almost imperceptible, making daily health monitoring less intrusive for patients.

“We expect that our findings will assist in the development of other sheet-type sensor systems that can perform precise biomonitoring when affixed to the skin surface,” said Tsuyoshi Sekitani, the senior author. Additional modules could enable features such as wireless communication with smartphones or computers.

This innovation not only enhances the practicality and comfort of wearable health monitors but also represents a significant step towards more efficient and user-friendly healthcare solutions.

By Impact Lab