KOSEN 한인과학기술자네트워크

1. 3D Bioprinting and Biofabrication

Development of inkjet-based 3D-bioprinting technology and printable biomaterials

Inkjet-spray based bioprinting technique is newly developed. Also, a novel and facile modification method which can be applied on bioinks whose molecular weight is too high to be inkjet printable is proposed. Using the technique and method, it is expected that large scale hydrogel with excellent mechanical property and high resolution can be generated.

3D printed human skin equivalents

Full-thickness human skin equivalents are being fabricated using 3D bioprinting. With high-resolution bioprinting, customized 3D skin models for biomedical and cosmetic tests are available. Also, automated and controlled deposition of biomaterials enables fabrication of the end products with high reproducibility.

Printed alveolar-capillary barrier model

The recent emergence of bioprinting technologies has enabled creating 3D tissues for the development of biomimetic human tissues. We develop alveolar-capillary barrier model with the 3D inkjet-based bioprinting technology. High-resolution inkjet printing system enables the fabrication of functionally designed and micro-patterned alveolar-capillary structures by precise deposition of multi-type cells. Printed micro lung models are expected to be applied for disease studies, drug discovery and toxicology.

Bioprinting of bladder cancer cells for the development of high-throughput screening system

Inkjet bioprinting technique allows us to deposit tiny amount of cells on pre-designated position with high speed and accuracy. These features can be applied in HTS field where mimicking tumor micro-environment is often neglected. Through controlling the number and position of the tumor tissue components, inkjet printing is highly expected to build more biologically relevant drug screening models.

Printing based spore fabrication

Algae spores are encapsulated as a picoliter-sized droplet and deposited into patterns using inkjet printing. Controlled and quantified encapsulation of spores is expected to open ways of efficient marine afforestation.

2. Flexible Printed Electronics

Design and fabrication of innovative 3D flexible circuits and systems

Circuits and systems requires no static power dissipation, wide noise margins, and high operational performance stability. In silicon-based integrated circuits, these requirements were achieved by using complementary (both p- and n-type) transistors. The same approach was adopted for the implementation of organic complementary circuits. We have adopted the 3D integration of complementary organic field-effect transistors (OFETs) to overcome the physical limits of the conventional 2D integration.  Based on this 3D integration, we are fabricating various organic circuits with high transistor density. Also, we are focusing on the development of robust and predictable fabrication process of flexible organic integrated circuits based on inkjet printing technique that is applicable to low cost roll-to-roll process.

Wearable computers

Low-temperature processed organic field-effect transistors (FETs) on flexible substrates will allow new applications including wearable computers. We develop 3-dimensionally stacked organic FETs fabrication process using printing techniques (dispensing and inkjet printing) on 1 micrometer thickness parylene thin films. Large-area, ultralight, and low-cost wearable computers are expected to appear in the near future.

Process design kit for 3D-printed circuits

Most state-of-art printed circuits still remain at the level of simple logic gates or basic circuit components. To develop complex printed ICs that can perform various functions, we need a more systematic design approach in FET printing fabrication process. Process design kit (PDK) indicates a set of process files which contain physical layout rules, SPICE models, and process information. PDK helps circuit designers to reduce human errors and process failures. We are currently focusing on development of a custom PDK for printed electronic circuits, which do not exist in commercial form. Our interests include printing rules for patterning functional materials and compact SPICE models for printed FETs.

Organic Light-Emitting Diode (OLED) and Organic Photovoltaics (OPV)

Flexible and foldable OLEDs have potential applications in next-generation optoelectronics due to advantages such as lightweight, self-emitting property, low driving voltage, and applicability to flexible large-area display and lighting. To develop OLED driven by OPV power, series and parallel-connected OPV mini-modules are designed. The OPV mini-module fabricated on 25cm2 plastic substrate generated over 5 volt under stand light.

3. Flexible and Wearable Sensors

Development of wearable sensor systems for healthcare field

Wearable sensors are certainly something that will be the key of our future society, especially when it comes to healthcare field. Various signals from human body, such as Electromyography (EMG), saturation of percutaneous oxygen (SpO2), and blood pressure can be measured at the skin interface with wearable sensors. We not only design but also fabricate various wearable sensors with printing technology. Wearable technologies will play a prominent role in future healthcare transformation.

Ultra-thin functional sensor network for Internet of Things (IOT)

As the Fourth Industrial Revolution is building on the third, things get connected by mobile devices and this will be multiplied by emerging technology breakthroughs in fields such as the Internet of Things, 3-D printing, and biotechnology. We fabricate functional sensor networks on ultra-thin substrates and integrate them with flexible printed signal processing circuits. We also incorporate bioelectronics to fabricate smart sensors. These technologies will take a major role in future industries.

Organic FET-based flexible sensors including a lactate / a pressure / a pH / and a light sensor

Organic Field Effect Transistors (OFETs) possess attractive properties such as mechanical flexibility, printability, simple integration and low manufacturing costs. Various detection targets such as a lactate / a pressure / a pH / and a light sensor are under research, and new creative sensors are always in our interests. These OFETs-based sensors can be potentially applied to wearable and disposable (or reuseable) biosensors.