▲ Korea Institute of Science and Technology (KIST) Next-Generation Semiconductor Research Institute Dr. Hyun-Jung Lee and Jeong-A Lim The research team produces the desired electrode by printing it with an inkjet printer and rolls the electrode thread coated with a semiconductor on it, and the desired electrode structure is rolled up. It has developed a technology that can manufacture fibrous electronic devices such as photodiodes.[기계신문] With the development of wearable devices, E-textile technology, which combines light and comfortable fibers with smart electronic devices, is drawing attention as a next-generation new technology. In particular, a fiber electronic device having electrical characteristics while maintaining the inherent characteristics of a fiber is one of the key devices for implementing an electronic fiber.
In general, in optoelectronic devices composed of layers such as semiconductors, electrodes, and insulating films, the device performance varies greatly depending on the size and structure of the electrodes. In order to make a fibrous electronic device, it bends easily and the device has to be formed on a thin thread, so the size of the device cannot be made larger than the thickness of the thread in micrometer units, so there is a limit to improving the performance of the device.
However, it is a topic recently that a domestic research team has developed a technology that improves performance beyond these limits. Korea Advanced Institute of Science and Technology (KIST) Next Generation Semiconductor Research Institute Dr. Hyun-Jung Lee and Jeong-A Lim The research team produces the desired electrode by printing it with an inkjet printer. It has developed a technology that can manufacture fiber-type electronic devices such as diodes.
In 2019, Dr. Hyun-Jung Lee’s team developed a technology that printed carbon nanotube (CNT) ink on a hydrogel substrate, which is a polymer containing water, and then transferred to form an electrode on a desired surface. have.
The CNT electrode printed on the hydrogel is like floating in water, and it is expected that if the fiber is rolled on it, it can be easily transferred to the surface of the fiber without damaging the electrode structure. As a result of research with Dr. Jeong-ah Lim’s team, the actual semiconductor layer and CNT A high-performance fibrous device was fabricated without damaging the electrode.
▲ A schematic diagram of a strategy for implementing a photoelectric device for monitoring human body signals through CNT electrode transfer. The electrode is transferred by printing the electrode on the hydrogel and rolling the fiber over the electrode (left).The photodiode produced through the transfer process is inserted into the fiber, and a schematic diagram applied to the optical blood flow measurement at the fingertip and the actual heart rate measurement characteristics ( Right)The fibrous transistor wrapped with the developed CNT electrode maintained stable performance of more than 80% even when it was bent to a 1.75mm bending radius. In addition, by utilizing the translucent properties of the CNT electrode, it succeeded in fabricating a fiber-type photodiode that can sense light by wrapping the electrode seal coated with a semiconductor layer that can generate current by absorbing light with a CNT electrode.
▲ (a) CNT electrode transfer process to implement a fibrous device developed by the research team, (b) A photo of the electrode of the desired size wrapped around the thread using the technology developed by the research teamThe fabricated fibrous photodiode can detect light in a wide visible light range and has excellent sensitivity that is not inferior to that of planar devices. When the fiber-type photodiode developed by the research team is inserted into a fabric with an LED element and worn like a glove, the fiber-type photodiode detects the intensity of reflection of the LED light that changes according to the change in the amount of blood flowing from the fingertips, and can measure the user’s pulse. there was.
Dr. Lim Jeong-ah of KIST explained, “The developed glove-type heart rate meter replaces the pincer-type heart rate meter, so you can easily approach the person with a comfortable and soft feeling, and it has the advantage of being able to measure your heart rate in real time anywhere, anytime.”
▲ When the fiber-type photodiode developed by the research team is inserted into a cloth with the LED element and worn like a glove, the fiber-type photodiode detects the intensity of the reflection of the LED light that changes according to the change in the amount of blood flowing from the fingertips and measures the user’s pulse. CouldDr. Lee Hyun-jung said, “This research presents a new approach to electrode formation technology, which remains a task in the development of fiber-type devices, and can accelerate the development of fibrous electronic devices with complex circuits from improving the performance of fiber-type optoelectronic devices. I look forward to it.”
On the other hand, this research was carried out as a major project of KIST under the support of the Ministry of Science and ICT, as well as a mid-level follow-up study of the National Research Foundation of Korea, and a nanomaterial original technology development project, and was published in the latest issue of the international academic journal’ACS Nano’
Machinery News, Machinery Industry News Channel
Reporter Oh Sang-mi [email protected]