• 제목/요약/키워드: carbon-hydrogel electrode

검색결과 9건 처리시간 0.023초

MREIT of Postmortem Swine Legs using Carbon-hydrogel Electrodes

  • Minhas, Atul S.;Jeong, Woo-Chul;Kim, Young-Tae;Kim, Hyung-Joong;Lee, Tae-Hwi;Woo, Eung-Je
    • 대한의용생체공학회:의공학회지
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    • 제29권6호
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    • pp.436-442
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    • 2008
  • Magnetic resonance electrical impedance tomography(MREIT) has been suggested to produce cross-sectional conductivity images of an electrically conducting object such as the human body. In most previous studies, recessed electrodes have been used to inject imaging currents into the object. An MRI scanner was used to capture induced magnetic flux density data inside the object and a conductivity image reconstruction algorithm was applied to the data. This paper reports the performance of a thin and flexible carbon-hydrogel electrode that replaces the bulky and rigid recessed electrode in previous studies. The new carbon-hydrogel electrode produces a negligible amount of artifacts in MR and conductivity images and significantly simplifies the experimental procedure. We can fabricate the electrode in different shapes and sizes. Adding a layer of conductive adhesive, we can easily attach the electrode on an irregular surface with an excellent contact. Using a pair of carbon-hydrogel electrodes with a large contact area, we may inject an imaging current with increased amplitude primarily due to a reduced average current density underneath the electrodes. Before we apply the new electrode to a human subject, we evaluated its performance by conducting MREIT imaging experiments of five swine legs. Reconstructed conductivity images of the swine legs show a good contrast among different muscles and bones. We suggest a future study of human experiments using the carbon-hydrogel electrode following the guideline proposed in this paper.

Simple Electrochemical Immunosensor for the Determination of Rabbit IgG Using Osmium Redox Polymer Films

  • Choi, Young-Bong;Lee, Seung-Hwa;Tae, Gun-Sik
    • 전기화학회지
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    • 제10권3호
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    • pp.229-232
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    • 2007
  • An amperometric immunosensor for the determination of rabbit IgG is proposed. The immunoassay utilizes a screen-printed carbon electrode on which osmium redox polymer is electrodeposited. This immunoassay detects 0.1 ng/ml of rabbit IgG, which is ${\sim}10^2$ fold higher than the most sensitive enzyme amplified amperometric immunoassay. The assay utilizes a screen-printed carbon electrode which was pre-coated by a co-electrodeposited film of an electron conducting redox hydrogel and a rabbit IgG. The rabbit IgG in the electron conducting film conjugates captures, when present, the anti-rabbit IgG. The captured anti-rabbit-IgG is labeled with horseradish peroxidase (HRP) which catalyzes the two-electron reduction of $H_2O_2$ to water. Because the redox hydrogel electrically connects HRP reaction centers to the electrode, completion of the sandwich converts the film from non-electrocatalytic to electro-catalytic for the reduction of $H_2O_2$ to $H_2O$ when the electrode is poised at 200 mV vs. Ag/AgCl.

Enhancement of Electrocatalytic Activity upon the Addition of Single Wall Carbon Nanotube to the Redox-hydrogel-based Glucose Sensor

  • Kim, Suk-Joon;Quan, Yuzhong;Ha, Eunhyeon;Shin, Woonsup
    • Journal of Electrochemical Science and Technology
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    • 제12권1호
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    • pp.33-37
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    • 2021
  • In electrochemical glucose sensing, the enhancement of the sensitivity and the response time is essential in developing stable and reliable sensors, especially for continuous glucose monitoring. We developed a method to increase the sensitivity and to shorten the response time for the sensing upon the appropriate addition of single wall carbon nanotube onto the osmium polymer-based hydrogel electrode. Also, the background stabilization is dramatically enhanced.

수소이온전도성 고분자 겔전해질을 적용한 활성탄소계 전기이중층 캐패시터의 전기화학적 특성 (Electrochemical Properties of Activated Carbon Capacitor Adopting a Proton-conducting Hydrogel Polymer Electrolyte)

  • 모하메드 라티파두;김광만;김용주;고장면
    • Elastomers and Composites
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    • 제47권4호
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    • pp.292-296
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    • 2012
  • 폴리비닐알콜, 규소텅스텐산, 인산 및 수용액으로 구성된 $80{\mu}m$의 두께의 고분자겔 전해질 필름을 제조하여 활성탄소계 전기이중층 케페시터를 제조하였다. 제조한 고분자겔 전해질 필름은 상온에서 $10^{-2}S\;cm^{-1}$의 높은 이온전도도를 나타내었으며, 본 전해질 필름을 적용한 활성탄소계 전기이중층 케패시터는 100 mV/s에서 $58F\;g^{-1}$의 높은 캐패시턴스 특성과 우수한 수명특성을 나타내었다.

3T MREIT 시스템을 이용한 실험견 사체의 두부 도전율 영상 (Conductivity Imaging of a Canine Head using a 3T MREIT System with a Carbon-Hydrogel Electrode: Postmortem Experiment)

  • 정우철;김영태;;김형중;이태휘;강병택;박희명;우응제
    • 대한의용생체공학회:의공학회지
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    • 제30권2호
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    • pp.179-184
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    • 2009
  • Magnetic Resonance Electrical Impedance Tomography (MREIT) is a new bio-imaging modality providing cross-sectional conductivity images from measurements of internal magnetic flux densities produced by externally injected currents. Recent MREIT studies demonstrated successful conductivity image reconstructions of postmortem and in vivo canine brain. However, the whole head imaging was not achieved due to technical issues related with electrodes and noise in measured magnetic flux density data. In this study, we used a new carbon-hydrogel electrode with a large contact area and injected 30 mA imaging current through a canine head. Using a 3T MREIT system, we performed a postmortem canine experiment and produced high-resolution conductivity images of the entire canine head. Collecting magnetic flux density data inside the head subject to multiple injection currents, we reconstructed cross-sectional conductivity images using the harmonic $B_z$ algorithm. The conductivity images of the canine head show a good contrast not only inside the brain region including white and gray matter but also outside the brain region including the skull, temporalis muscle, mandible, lingualis proprius muscle, and masseter muscle.

Amperometric Detection of DNA by Electroreducation of O2 in an Enzyme-Amplified Two-Component Assay

  • Yoon Chang-Jung;Kim Hyug-Han
    • 전기화학회지
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    • 제7권1호
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    • pp.44-48
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    • 2004
  • The two-component type enzyme amplified amperometric DNA assay is described to use an ambient $O_2$ of the substrate of the DNA labeling enzyme. Although the assay detects DNA only at > 0.5M concentration, a concentration $\~10^6$ fold higher than the sandwich-type enzyme amplified amperometric DNA assay, it can be run with an always available substrate. The assay utilizes screen-printed carbon electrodes (SPEs) which were pre-coated by a co-electrodeposited film of an electron conducting redox hydrogel and a 37-base long single-stranded DNA sequence. The DNA in the electron conducting film hybridizes and captures, when present, the 37-base long detection-DNA, which is labeled with bilirubin oxidase (BOD), an enzyme catalyzing the four-electron reduction of $O_2$ to water. Because the redox hydrogel electrically connects the BOD reaction centers to the electrode, completion of the sandwich converts the film from non-electrocatalytic to electrocatalytic for the reduction of $O_2$ to water when the electrode is poised at 200 mV vs. Ag/hgCl. The advantage or the assay over the earlier reported sandwich type enzyme amplified amperometric DNA assay, in which the amplifying enzyme was horseradish peroxidase, is that it utilizes ambient $O_2$ instead of the less stable and naturally unavailable $H_2O_2$.

친수성 실리카와 하이드로겔 전해질이 적용된 활성탄 수퍼커패시터의 전기화학적 특성 (Electrochemical Properties of Activated Carbon Supercapacitors Adopting Hydrophilic Silica and Hydrogel Electrolytes)

  • 이해수;박장우;이용민;유명현;김광만;고장면
    • Korean Chemical Engineering Research
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    • 제54권3호
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    • pp.293-298
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    • 2016
  • 6M의 KOH 수계 전해액에 potassium polyacrylate (PAAK)가 3 wt.% 포함된 하이드로겔 전해질을 제조하고, 이에 친수성 실리카 OX50을 1 wt.% 포함시킨 하이드로겔 전해질을 함께 제조하고, 이를 Scimat 분리막에 코팅 및 건조하여 활성탄 수퍼커패시터의 자기지지체 전해질/분리막으로 사용하여 그 실리카 첨가효과를 조사하였다. 실리카 입자는 다공성 분리막 지지체의 표면기공에 균일하게 분포하여 하이드로겔의 이온전도도와 전기화학적 안정성을 향상시켰으며 이에 따라 고속스캔 조건에서도 활성탄 수퍼커패시터의 비축전용량이 비교적 높게 유지되었는데, 이는 실리카가 포함된 하이드로겔 전해질이 활성탄 전극과 분리막 사이에서의 계면저항이 감소하기 때문이다.

Poly(acrylonitrile) 부직포 분리막에 코팅된 하이드로겔 고분자 전해질을 포함하는 활성탄 수퍼커패시터 특성 (Electrochemical Properties of Activated Carbon Supecapacitor Containing Poly(acrylonitrile) Nonwoven Separator Coated by a Hydrogel Polymer Electrolyte)

  • 모하메드 라티파투;고장면;이영기;김광만;조정대;장윤석;유정준;김종휘
    • Korean Chemical Engineering Research
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    • 제51권5호
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    • pp.550-555
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    • 2013
  • 6M KOH 수계 전해액에 potassium poly(acrylate) (PAAK)를 3 wt% 포함시켜 제조한 하이드로겔을 poly(acrylonitrile)부직포 분리막에 코팅하고, 이를 활성탄 수퍼커패시터의 분리막 및 전해질로 사용하여 수퍼커패시터의 고율특성 향상을 시도하였다. 이 분리막 및 전해질은전자현미경 관찰 결과 PAAK 하이드로겔이 부직포의 표면기공에 균일하게 코팅되어 있으며, 24일 동안 하이드로겔의 합습도가 230% 이상으로 균일하게 유지되었고, 6 M KOH 전해액을 사용한 경우($3.6{\times}10^{-2}Scm^{-1}$)보다 약간 낮은 $2.9{\times}10^{-2}Scm^{-1}$의 이온전도도를 나타내었다. 활성탄을 활물질로 사용한 대칭형 수퍼커패시터에 이 분리막 및 전해질을 채택한 경우 사이클릭볼타메트리 시험에서 $1000mVs^{-1}$의 고속스캔 조건에서도 $27Fg^{-1}$ 이상의 높은 비축전용량과 1000 사이클 경과후에도 97% 이상의 유지율을 나타내는데, 이는 부직포 상에 코팅된 PAAK 하이드로겔 전해질이 활성탄 전극과 부직포 분리막 사이에서 강력한 계면밀착을 유지할 수 있기 때문이다.

사진식각법을 이용한 FET형 용존 $CO_{2}$ 센서의 수화젤막 및 가스 투과막 제작 (Fabrication of Hydrogel and Gas Permeable Membranes for FET Type Dissolved $CO_{2}$ Sensor by Photolithographic Method)

  • 박이순;김상태;고광락
    • 센서학회지
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    • 제6권3호
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    • pp.207-213
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    • 1997
  • $H^{+}$ 이온에 선택적으로 감응하는 field effect transistor(pH-ISFET)를 바탕소자로 하고, 그 gate 주위에 Ag/AgCl 기준전극을 형성한 다음, 이를 둘러싼 수화젤(hydrogel)막 및 기체투과막의 이중막 구조를 가진 용존이산화탄소($CO_{2(aq)}$) 센서소자를 사진식각(photolithography)법으로 제작하였다. PVA-SbQ 혹은 PVP-PVAc/감광제 형의 광가교형 감광액은 수화젤막 형성에 적합하지 않았으나, 2-hydroxyethyl methacrylate(HEMA) 및 acrylamide를 포함하는 광중합형 감광액을 사용할 경우에는 사진식각법에 의한 수화젤막이 좋은 해상도로 얻어졌다. 기체투과막은 urethane acrylate계 UV-oligomer를 주성분으로 한 감광액을 써서 사진식각법으로 수화젤막위에 형성할 수 있었다. 또한 수화젤막 및 기체투과막을 사진식각법으로 형성할 때 N,N,N',N'-tetramethyl ethplenediamine(TED) 을 $O_{2}$ quencher로서 감광액 중에 도입함으로써 UV 노광시에 polyester film을 부착하는 번거로운 공정을 생략할 수 있음을 알았다. 이렇게 제조된 $pCO_{2}$ 센서는 수용액 중에서 $10^{-3}{\sim}10^{0}\;mol/{\ell}$$CO_{2}$ 농도변화에 대하여 직선적인 검정곡선(calibration curve)을 얻을 수 있었다.

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