• Proceedings of the Korean Magnestics Society Conference
• /
• 2007.05a
• /
• pp.328.1-328.1
• /
• 2007

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.2
• /
• pp.117-122
• /
• 2016

Recently, the detection of pH with real-time and in vivo has been focal pointed in the environmental or medical fields. In this work, we developed the pH sensor using graphene sheet. Graphene has high biocompatibility. We fabricated flexible solution-gated field-effect transistors (SGFETs) on graphene sheet transferred on the polyethylene terephthalate (PET) substrate to detect pH in electrolyte solution. The gate length was $500{\mu}m$ and the gate width was 8 mm. We evaluated the current-voltage (I-V) transfer characteristics of graphene SGFETs in pH solution. The drain-source current ($I_{DS}$) and the gate-source voltage ($V_{GS}$) curves of graphene SGFETs were depended on pH value. The Dirac point of graphene SGFETs linearly shifted to the positive direction about 19.32 mV/pH depending on the pH value in electrolyte solution.

• Food Science and Biotechnology
• /
• v.14 no.3
• /
• pp.358-362
• /
• 2005

Eudragit E100 microcapsules containing nisin were prepared and employed to control the ripening of kimchi. The recovery yields of microcapsules without/with nisin ranged from 93.53 to 94.61 % and 92.85 to 94.09 %, respectively. The particle size of microcapsules decreased (>200 to $100\;{\mu}m$) as the amount of aluminium tristearate increased from 6.0 to 15 %. The microcapsules were morphologically spherical and possessed rough surface. Nisin was completely released from the microcapsules within a day at pH 3.0 and within two days at pH 4.0, 5.0, and 6.0, respectively, whereas half the amount of nisin was released at pH 7.0 within two days. During fermentation of kimchi with microcapsules containing nisin, the pH decrease was retarded which resulted in a constant pH of approximately 4.2. The pH of 4.2 was optimal for ripening of kimchi for a longer period of time when compared with samples without nisin.

• Clinical and Experimental Reproductive Medicine
• /
• v.3 no.1
• /
• pp.13-19
• /
• 1976

Serum levels of human placental lactogen have been measured by hemagglutination-inhibition reaction in 67 normal pregnant state and in 15 postpartum 24 hour state, HAIR is less sensitive and reliable method than radioimmunoassay, but simple, rapid, less expensive and fairly accurate, so it is more helpful in screening of large antenatal population with or without high risk complications. 1) Sensitivity of HPL-HAIR test kit was $0.1{\mu}g$/ml of H.P.L. serum level and had no cross reaction to HCG or male serum or non-pregenant female or newborn infant, 2) H.P.L. value was around $2{\mu}g$/ml until 24th week of pregnancy and rose to $6{\sim}8$ ${\mu}g$/ml continuously until about 36th week of pregnancy and then slightly decreased or stationary. 3) H.P.L. value in postpartum 24 hour state was undetectable. 4) There was poor correlation between maternal serum H.P.L. value at term and baby weight.

• Proceedings of the Membrane Society of Korea Conference
• /
• 1996.10a
• /
• pp.80-81
• /
• 1996

일반적으로 고분자전해질은 고유의 독특한 특성으로 고분자 분리막, 이온교환수지, 의료용고분자등에 널리 응용이 되고 있다. 이러한 고분자전해질은 음이온성과 양이온성이 있으며, 그 이온적성질으로 인하여 반대의 전하를 띄는 고분자전해질들끼리 결합하는 성질을 가지고 있다. 이러한 고분자전해질 착체는 고분자전해질과는 또 다른 고유한 특성을 나타내고 있으며, 특히 고분자분리막과 의료용재료 분야에 응용가능성이 큰 물질이다. 특히 양이온성과 음이온성을 동시에 보유하고 있는 구조적 특성에 의하여 산성과 염기성 모두에서 감응성을 나타낼 수 있다. 일반적으로 고분자 겔의 경우 산성 또는 염기성 영역에서 해리되는 특성에 의하여 pH 감응성을 나타내지만 한쪽 영역에서만 특성을 나타내고 있다. 본 실험에서는 키토산과 폴리아크릴산으로 제조된 고분자전해질착체를 이용하여 pH변화에 따른 함수거동을 관찰함으로써 양쪽의 pH 감응성을 고찰해보고자 하였다.

• Journal of Sensor Science and Technology
• /
• v.6 no.2
• /
• pp.131-136
• /
• 1997

The ISFET(ion sensitive field effect transistor), a semiconductor ion sensor, has many advantages over conventional ion sensors. Various single-sensor type ISFET pH-meters have been developed. However, they could not be applied in fields because their performances are directly affected by the sensor condition. With only one sensor, the system could be easily damaged from environmental factors, and reliability of it is decreased. Therefore, a 4-channel PH-meter system is proposed to improve the reliability of ISFET pH-meter. It has 4 ISFETS as ion sensor, and a software which contains a new calibration and measurement algorithm appropriate to the system. The reliability of the system was proved by measuring hydrogen ion concentration in the pH standard solutions and buffer solutions.

• 한국생물공학회:학술대회논문집
• /
• 2005.10a
• /
• pp.808-809
• /
• 2005

• Bulletin of the Korean Chemical Society
• /
• v.34 no.1
• /
• pp.287-290
• /
• 2013

• Journal of Sensor Science and Technology
• /
• v.1 no.2
• /
• pp.101-106
• /
• 1992

pH-ISFETs, the semiconductor pH sensors, were combined with immobilized enzyme membranes to prepare FET type urea and glucose sensors and its operational characteristics were investigated. Photolithography techniques were applied to immobilize enzymes on the $H^{+}$ sensing membrane of the pH-ISFET with photo-sensitive polymers, PVA-SbQ. Fabricated urea and glucose sensors could determine $0.5{\sim}50{\;}mg/dl$ urea concentrations and $10{\sim}1000{\;}mg/dl$ glucose concentrations, respectively.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.22 no.6
• /
• pp.28-33
• /
• 1985

ISFETS for physiological applications have been developed using the techniques for integrated circuit fabrication. The silicon nitride layer was used as a H+ sensing membrane. However, K+, Na+ and Ca++ sensing ISFETS were fabricated by forming tach specification sensing membranes over the silicon nitride gate insulator. The sensitivities of the fabricated devices were very good. The typical values of measured sentivities were iEmV/pH, 42mv1, pH,5 gmV/pNa and 28mv1p0a. However, the selectivity and stability should be somewhat improved for practical physiological uses with good reliability. The response times were, less than one second, short enough for the practical uses in physiological applications.