The Active Aging Research Institute of Waseda University brings together young researchers from different fields of biomaterials, mechatronics, and MEMS to fix electronic devices using the flexibility and adhesion of polymer nanosheets without using heat treatment. Announced that it has developed a sealing technology that energizes.Furthermore, we succeeded in stably energizing the developed device even on the surface of flexible living tissue.
In recent years, wearable devices that measure biological information (body temperature, pulse, blood pressure, blood oxygen concentration, pH, myoelectric potential, etc.) by wearing them on the body like a shirt or a wristwatch are becoming widespread.In addition, with the progress of thin film forming technology, it is expected that the form of next-generation wearable devices will advance to the era of "sticking" to living tissues such as skin like adhesive plasters.It is necessary to attach the elements that make up the electronic circuit to the surface of a soft plastic thin film so that there is no discomfort when pasted, but the conventional method of fixing electronic elements has the problem that the joints that require high-temperature treatment are cured. The thinner the base material, the more difficult it was to fix the element stably.
Therefore, the research group has developed a sealing technology that fixes and energizes electronic devices by a method that does not use heat treatment by utilizing the flexibility and adhesion of polymer nanosheets.Nanosheets exhibit high flexibility and adhesion due to their ultra-thinness of tens to hundreds of nanometers.In this research, we verified the printing of conductive silver ink on the surface of this nanosheet, the encapsulation of wiring and elements using the flexibility and adhesion of nanosheets, and the operability of devices equipped with LEDs on the skin. bottom.
As a result of the verification, when the electronic element was sandwiched between nanosheets called SBS, we succeeded in connecting the wiring and the electronic element by utilizing the flexibility and adhesion of the nanosheet without using a high temperature treatment process such as soldering.In addition, the thinner the film thickness of the nanosheet, the better the airtightness of the electronic element, and since it was possible to connect with a smaller contact resistance value, the electrical connection between the printed wiring and the element has the flexibility and adhesion peculiar to the nanosheet. It was clarified that it was derived.Furthermore, when a device consisting of SBS nanosheets and LEDs (total film thickness of the sheet: about 800 nm) was attached to the skin, we succeeded in stably lighting the LEDs even on the surface of flexible living tissue.
The method developed in this research has the advantage that the base material is thin and soft, so that it does not feel uncomfortable when attached to the skin and has high adhesiveness.Furthermore, it can be applied to plastic substrates and electronic devices with low heat resistance, and is also useful for encapsulating precision equipment such as IC chips.In addition, the wiring of electronic circuits can be designed and printed with a household inkjet printer, and if nanosheets are used as the printing substrate and encapsulant, anyone can easily and inexpensively produce "skin-attached electronics" for learning. It is also expected to be used as a kit.
