Korean researchers have announced a study that will accelerate the performance improvement of ‘stretchable electronics’ technology, a core technology of wearable devices.
On 28^th this month, SNU College of Engineering (Dean Lee Kun-Woo) announced that Dept. of Electrical & Computer Engineering Prof. Hong Yong-Taek’s research team (researcher Byun Jeong-Hwan, Oh Eun-Ho) has realized a circuit capable of high-speed signal processing above 1 MHz on a flexible board using double-sided printing technique and stretchable hybrid electronic technology. As a result, green light has been turned on in the development of health-monitoring wearable devices that attach to the body.
Since stretchable electronic circuit does not lose its electrical characteristics even if it is attached to a curved surface or the board’s shape is deformed, it has been expected to be highly applicable as a wearable device. However, there was a limitation in that the measured signals must be processed using a large computation device installed externally, because the conventional devices could not incorporate circuits for signal processing and calculation.
So the team has applied the ‘stretchable hybrid electronic’ technology to produce a stretchable platform that allows high-performance silicon-based chips to be embedded in flexible circuits. The team used dispensing technique to insert a PMMA (poly methyl methacrylate) plastic material with a high modulus of elasticity into a flexible PDMS (poly-dimethyl siloxne) board, and mounted the chip on it to improve the stability of the circuit.
In addition, the team developed a method of forming ’stretchable vias’ together on the board without directly punching holes on the board when manufacturing. By forming a self-assembled core-shell structure in which conductive nickel particles are surrounded by a rigid polymer, stable electrical and mechanical properties can be maintained even in circuit board deformation.
As a result, a stretchable electronic platform that allows chip mounting and circuit formation using double-sided printing processes was created. In particular, the platform’s usable area and the circuit’s degree of integration have doubled because the circuits on both sides can be electrically connected due the embedment of stretchable via.
Using this platform, the team implemented a binary decoder consisting of various chip-based logic circuits, and succeeded in operating at 1MHz even under external mechanical stretching stress.
Prof. Hong explained that “optimizing the position and shape of the inserted OMMA plastic structure and developing a process to manufacture the stretchable vias have brought this innovative result.” And that “we have founded a technical basis for high-speed signal processing and calculation without separate signal processing equipment.”
The research result was published online in the August 3^rd issue of ‘Advanced Functional Materials’. This research was supported by the Institute for Information & communication Technology Promotion.