Researchers from an international research group have developed a novel, high-strength flexible device that combines piezoelectric composites with unidirectional carbon fiber (UDCF) to create efficient and reliable motion sensors. The device converts kinetic energy from human motion into electricity, providing a sustainable solution for high-strength and self-powered sensors. The details of this research were recently published in the journal Small on December 14, 2023.
Motion detection, which involves converting energy from human motion into measurable electrical signals, is increasingly important in ensuring a sustainable future. Everyday items, such as protective gear and sports equipment, are now part of the Internet of Things (IoT) and equipped with sensors to collect data. Fumio Narita, co-author of the study and a professor at Tohoku University’s Graduate School of Environmental Studies, explains that integrating these IoT devices into personal gear requires innovative solutions in power management and material design to ensure durability and flexibility.
Piezoelectric materials have the ability to generate electricity when physically stressed, making them ideal for utilizing mechanical energy. Carbon fiber, known for its durability and lightness, is widely used in industries such as aerospace, automotive, sports equipment, and medical equipment. The researchers wondered if combining carbon fiber with a piezoelectric composite could create flexible personal protective equipment that offers comfort, durability, and sensing capabilities.
To fabricate the device, the researchers combined unidirectional carbon fiber fabric (UDCF) with potassium sodium niobate (KNN) nanoparticles mixed with epoxy (EP) resin. The UDCF served as both an electrode and a directional reinforcement. The resulting UDCF/KNN-EP device performed exceptionally well in tests, maintaining high performance even after being stretched more than 1,000 times.
Compared to other flexible materials, the UDCF/KNN-EP device demonstrated the ability to withstand higher loads when pulled along the fiber direction. It also outperformed other piezoelectric polymers in terms of energy output density when subjected to impacts and stretching perpendicular to the fiber direction. The mechanical and piezoelectric responses of the UDCF/KNN-EP device were analyzed using multi-scale simulations in collaboration with Professor Uetsuji’s group at the Osaka Institute of Technology.
This new development of the UDCF/KNN-EP device is expected to advance the development of flexible, self-powered IoT sensors and contribute to the creation of advanced multi-functional IoT devices. The researchers integrated the UDCF/KNN-EP device into sports equipment, where it accurately detected impacts from catching a baseball and measured a person’s step frequency. Leveraging the high strength of carbon fibers, the device improves the sustainability and reliability of battery-free sensors while maintaining their directional stretchability. The study provides valuable insights and guidance for future research in the field of motion detection.
The breakthrough in using piezo composites with carbon fibers for motion sensors opens up new possibilities for the integration of sensors in various applications. The flexibility, strength, and self-powered capabilities of the UDCF/KNN-EP device make it a promising solution for sustainable and reliable motion detection systems. As technology continues to advance, we can expect further improvements and innovations in the field of motion sensors.