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신정활,정진화,남효영,김성원,조동우,임근배 한국바이오칩학회 2015 BioChip Journal Vol.9 No.1
Cartilage regeneration is a major challengefor researchers because cartilage tissue has limitedinnate regenerative ability. Encapsulation within analginate gel has been used widely for 3D scaffolds togenerate cartilage-like tissue, but alginate gels havelimitations such as poor mechanical properties. In thisstudy, we fabricated alginate microfibers for humanseptal chondrocyte (HSC) encapsulation and identifiedthe conditions that result in the optimal mechanicalproperties of the alginate microfibers. In vitro experimentsshowed that HSCs encapsulated within alginatemicrofibers maintained ¤90% viability for 7 days,and the 140 μm condition was more effective in termsof HSC proliferation than the 330 and 520 μm conditions. In vivo, HSCs differentiated gradually into cartilagetissue over 4 weeks in immunocompetent mice. Importantly, the alginate-encapsulated HSCs wereisolated and protected from the host immune responsedespite xenograft implantation.
The Development of Gelatin-Based Bio-Ink for Use in 3D Hybrid Bioprinting
신정활,강현욱 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.5
Numerous researchers have studied 3D hybrid bioprinting technology, as it appears to be a viable option for producing cellular constructs with clinical relevance. This technology uses a co-printing process with high strength bio-plastics and cell-laden bio-inks. The bio-inks used in this technology should be easily printable and provide good biological environment for artificial tissue regeneration. In this research, we present a gelatin-based bio-ink for 3D hybrid bioprinting. We prepared a variety of gelatin mixtures and evaluated them in terms of their printability. We also investigated the effects of using hyaluronan and glycerol as additives. The results showed that hyaluronan and glycerol enhanced the spatial resolution and uniformity of the printed patterns. We determined the optimal composition for the bio-ink and then conducted 2D and 3D cell patterning tests. The results showed that our bio-ink can produce a line width of approximately 200μm, and multiple types of cells can be positioned precisely in 3D structures. We also conducted a cytocompatibility test with NIH3T3 fibroblast. This test showed the processability of our bio-ink with living cells. Finally, we printed an actual-size, human ear-shaped construct. These experiments suggest that the proposed gelatin-based bio-ink is well suited for applications to 3D hybrid bioprinting technology.
Ionic liquid flow along the carbon nanotube with electric field
Jung Hwal Shin(신정활),Kanghyun Kim(김강현),WooSeok Choi(최우석),Geunbae Lim(임근배) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Liquid pumping can occur along the outer surface of an electrode under a DC electric field. For biological applications, a better understanding of the ionic solution pumping mechanism is required. Here, we fabricated CNT wire electrodes (CWEs) and tungsten wire electrodes (TWEs) of various diameters to assess an ionic solution pumping. A DC electric field created by a bias of several volts pumped the ionic solution in the direction of the negatively biased electrode. The resulting electro-osmotic flow was attributed to the movement of an electric double layer near the electrode, and the flow rates along the CWEs were on the order of picoliters per minute. According to electric field analysis, the z-directional electric field around the meniscus of the small electrode was more concentrated than that of the larger electrode. Thus, the pumping effect increased as the electrode diameter decreased. Interestingly in CWEs, the initiating voltage for liquid pumping did not change with increasing diameter, up to 20 ㎛. We classified into three pumping zones, according to the initiating voltage and faradaic reaction. Liquid pumping using the CWEs could provide a new method for biological studies with adoptable flow rates and a larger ‘Recommended pumping zone’.
차소향,신정활 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.7
PDMS(Polydtmethylsiloxane) sponges were created using 3D printing technology that is different from conventional methods. The developed PDMS sponges can be used for oil/water separation due to their own hydrophobic characteristic. In this paper, we evaluated for practical use in the environment, a larger PDMS sponge(4×4×4 cm) was produced to separate the oil from the actual seawater. In addition, the change of water contact angle at various temperatures(3~35℃) was carried out.
김태현,홍민종,신정활 한국센서학회 2023 센서학회지 Vol.32 No.5
Throughout the 20th century, the transition of pig farms from extensive to intensive commercial operations amplified the risk of diseasetransmission, particularly involving African swine fever (ASF). Real-time temperature monitoring systems have emerged as essentialtools for early ASF diagnosis. In this paper, we introduce new real-time temperature monitoring ear tags (RTMEs) modeled afterexisting ear tag designs. Our crafted Pig-Temp platforms have three primary advantages. First, they can be effortlessly attached to pigears, ensuring superior compatibility. Second, they enable real-time temperature detection, and the data can be displayed on a personalcomputer or smartphone application. Furthermore, they demonstrate excellent measurement accuracy, ranging from 98.9% to 99.8% attemperatures between 2.2 and360o C. A linear regression approach enables fever symptoms associated with ASF to be identified within3 min using RTMEs. The communication range extends to approximately 12 m (452m2 ), enabling measurements from an estimated75 to 2,260 pigs per gateway. These newly developed Pig-Temp platforms offer singifcant enhancement of early ASF detection.
MPTMS Treated Au/PDMS Membrane for Flexible and Stretchable Strain Sensors
양성진,임현지,전형국,홍성경,신정활 한국센서학회 2016 센서학회지 Vol.25 No.4
Au/PDMS membranes are widely used to fabricate strain sensors which can detect input signals. An interfacial adhesion betweenmetal films and polydimethylsiloxane (PDMS) substrates is one of the important factors determining the performance of strain sensors,in terms of robustness, reliability, and sensitivity. Here, we fabricate Au/PDMS membranes with (3-mercaptopropyl) trimethoxysilane(MPTMS) treatment. PDMS membranes were fabricated by spin-coating and the thickness was controlled by varying the spin rates. Auelectrodes were deposited on the PDMS membrane by metal sputtering and the thickness was controlled by varying sputtering time.Owing to the MPTMS treatment, the interfacial adhesion between the Au electrode and the PDMS membrane was strengthened andthe membrane was highly transparent. The Au electrode, fabricated with a sputtering time of 50 s, had the highest gauge factor at a max-imum strain of ~0.7%, and the Au electrode fabricated with a sputtering time of 60 s had the maximum strain range among sputteringtimes of 50, 60, and 120 s. Our technique of using Au/PDMS with MPTMS treatment could be applied to the fabrication of strain sen-sors.