The world’s first flexible wireless organic sensor system
Disposable sensors for sticking plasters and diapers
Graduate School of Engineering / Faculty of Engineering
As a result of the recent rapid development of wireless sensors, they are in ever wider use to measure a variety of physical information in the real world, and the target of their measurement is expanding swiftly from objects to humans. In order to extract biological information from sensors that physically interact with the human body there is a need for functionality not required of conventional sensors, such as imperceptible softness and disposability from a hygienic perspective.
A research team led by Professor Takayasu Sakurai and Professor Takao Someya at the University of Tokyo has succeeded in developing the world’s first flexible wireless completely organic sensor system. The feasibility of this wireless system has been demonstrated by wirelessly supplying power and wirelessly transmitting data from a wet sensor. The sensor can be remotely powered, and data can be read from the sensor under optimal conditions.
The team has succeeded in developing a wirelessly powered flexible wet sensor sheet that transmits data wirelessly by implementing an organic integrated circuit (IC) on top of a polymeric film. Introducing for the first time in the field an electromagnetic-resonance method in power transmission for the operation of an organic IC was key to this achievement. This method enabled efficient wireless power and data transmission between the reader and the sensor over a distance. This organic IC is structured with three circuitry blocks. The first block receives power wirelessly by magnetic resonance at a rectifier circuit using organic diodes. The second block is placed on an organic ring oscillator with oscillating frequency that changes with resistance. The ring oscillator transmits the data of the resistance change caused by moisture or the presence of liquid. The third block is an electrostatic discharge (ESD) circuit comprising organic diodes protect the device from damage when touched by a charged human body (2-kV electrostatic discharge).The principle of this research could also be applied to sensors to detect humidity or pressure, other than moisture. This result will also find applications in a wide range of disposable sensors such as in sticking plasters and disposable diapers.
This achievement was presented at the 2014 IEEE International Solid-State Circuits Conference (ISSCC) in San Francisco, U.S.A, on February 12, 2014.
This research was carried out within the framework of the Strategic Basic Research Program of the Japan Science and Technology Agency (JST).
Press release (JST)
Hiroshi Fuketa, Kazuaki Yoshioka, Tomoyuki Yokota, Wakako Yukita, Mari Koizumi, Masaki Sekino, Tsuyoshi Sekitani, Makoto Takamiya, Takao Someya, and Takayasu Sakurai,
“Organic Transistor Based 2kV ESD Tolerant Flexible Wet Sensor Sheet for Biomedical Applications with Wireless Power and Data Transmission Using 13.56MHz Magnetic Resonance”,
IEEE International Solid-State Circuits Conference (ISSCC) Digest of Technical Papers pp. 490-491, Feb. 2014.