Precise determination of the lithium isotope ratio in geological samples using MC-ICP-MS with cool plasma

Choi, Min Seok,Ryu, Jong-Sik,Park, Ha Yan,Lee, Kwang-Sik,Kil, Youngwoo,Shin, Hyung Seon The Royal Society of Chemistry 2013 Journal of analytical atomic spectrometry Vol.28 No.4

<P>Lithium has two naturally occurring isotopes, <SUP>6</SUP>Li and <SUP>7</SUP>Li, with approximate relative abundances of 7.5% and 92.5%, respectively. Due to large Li isotope variations in nature, lithium isotopes have the potential to reveal important information relevant to nuclear technology, biomedicine, astrophysics, and geochemistry. With the advent of multi-collector inductively coupled mass spectrometry (MC-ICP-MS), studies of Li isotopes have largely focused on the analysis of geological materials, with varying degrees of accuracy. However, this technique has often been affected by either baseline interferences or isobaric interferences on mass 6 and 7 during ionization in Ar plasma, which is mainly due to the Li compound with hydrogen gas, and double-charged nitrogen and carbon ions at higher levels of RF power. In this study, we reduced baseline interferences in Ar plasma using a cool plasma (∼800 W) technique with a X-type cone. Lithium was separated using a cation exchange column (BioRad AG50W-X8, 200–400 mesh) with a mixture of 6 N HNO<SUB>3</SUB> and 80% methanol at <0.2 mL min<SUP>−1</SUP> elution speed. The short-term reproducibility of <I>δ</I><SUP>7</SUP>Li values of the NASS-5 seawater standard was 30.55 ± 0.45‰ (2<I>σ</I>, <I>n</I> = 15). Measured <I>δ</I><SUP>7</SUP>Li values of rock and seawater standards ranged from 2.48 to 30.55‰, in good agreements with reported values.</P> <P>Graphic Abstract</P><P>Average <I>δ</I><SUP>7</SUP>Li values of a pure L-SVEC Li solution and one passed through the column were 0.00 ± 0.23‰ (2<I>σ</I>, <I>n</I> = 26) and ¬0.01 ± 0.20 ‰ (2<I>σ</I> , <I>n</I> = 9), respectively, indicating that our chemical separation procedure for Li induces no mass fractionation. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2ja30293d'> </P>

오이 추출물에 존재하는 Superoxide Dismutase의 열안정성

김은애(Eun-Ae Kim),김기남(Gi-Nahm Kim),길지은(Ji-Eun Kil),이민경(Min-Kyung Lee),김석환(Suk-Hwan Kim),서정식(Chung-Sik Suh),박인식(Inshik Park) 한국식품영양과학회 1999 한국식품영양과학회지 Vol.27 No.6

오이속의 조효소액에 존재하는 Superoxide dismutase(SOD)활성의 pH 안정성은 pH 8.0에서 가장 안정하였고 pH5.0~9.0 사이의 범위에서는 비교적 안정하였다. 최적 온도는 25℃였고 열 안정성은 60℃까지는 안정하였다. 100℃에서 5분간 보관하였을 경우에는 12%만이 남아있었다. 오이에 존재하는 SOD 활성이 섭취 후에도 안정한가를 확인하기 위한 실험에서는 위속의 pH와 동일하도록 오이속의 조효소액의 pH를 2.0으로 변형시킨 후 36.7℃에서 3시간 동안 보관 후에 잔존활성이 10%였고, 장내의 환경인 pH 7.0으로 바꾸어 6시간 동안 둔 후 잔존하는 SOD의 활성은 25%로 활성이 증가되었다. 다양한 열처리 후에 잔존하는 오이의 SOD활성은 오이속은 데치기에서(끓는 물에서 2분) 25%, 껍질은 찌는 동안에(3분) 53%, 그리고 속과 껍질로 분리하지 않은 오이는 데치기에서 27%의 활성잔존률을 보였다. 4℃에서는 20일간 보관한 후에 오이속의 조효소액은 81%활성이 있었고, 30℃에서는 17%의 활성이 남아 있었다. 투석한 결과 SOD의 활성은 변화가 없었으므로 오이속에 존재하는 SOD는 적어도 분자량이 12,000 이상의 물질로 추정된다. The superoxide dismutase(SOD) in peeled pericarp of cucumber was most stable at pH 8.0 and relatively stabe between pH 5.0 and 9.0. The enzyme was stable up to 60℃ and retained 12% by heat treatment at 100℃ for 5 min. At pH 2.0, the peeled pericarp enzyme activity was decreased to 10% by incubation for 3 hrs. However, the enzyme activity was increased above 25% after incubating the enzyme at pH 7.0 for 6 hrs. Retention of SOD activity in cucumber by various heating methods was also measured. The residual SOD activities of peeled pericarp and whole cucumber was estimated to be 25% and 27% after blanching (2 min), respectively. The skin enzyme retained 53% of its activity after steaming (3 min). When the peeled peri carp enzyme was incubated at 4℃ for 20 days, the enzyme activity remained about 81%. However, when the enzyme incubated at 30℃ for 20 days, the peeled pericarp enzyme activity decreased to 17% of its original activity. The enzyme activity of peeled pericarp cucumber was not changed after exhaustive dialysis for 3 days, which indicated that the SOD activity in cucumber seems to have molecular weight above 12,000.

맹인·농아 청소년의 개인 및 환경 변인이 주체성 발달에 미치는 영향

김경식,민병근,이길홍 중앙대학교 의과대학 의과학연구소 1984 中央醫大誌 Vol.9 No.3

This study was intended to investigate some variables influencing the identity of Korean adolescent students, to compare the developmental levels of identity among normal, blind, and deaf-mute students and to clarify how handicaptee's personal and environmental variables exercise to influence on the development of different kinds of factors of identity. The data were collected by means of questionnare and interview with their teachers. Subjects served for this study consisted of 1815 adolescent students in Korea, randomly sampled from Korean student population using census method. The students ranged in age from 12 to 21. The actual number of cases put into the analysis was 1607 including 957 normal, 267 blind and 383 deaf-mute adolescents. The data were analyzed by a Prime 750 computer housed in the Hangang Sacred Heart Hospital of Hallym College using SPSS program. The statistical methods employed were x^2 test and simple correlations for personal and environmental variables ; R-type factor analysis for item analysis ; T-tests for comparing the factor scores between normal, blind, and deaf-mute groups ; and stepwise multiple regression analysis to ascertain the relationships between the adolescent's personal and environmental variables and their identity. The results were as follows: 1. The identity questionnaire given to normal adolescent students analysed the following factors in male:'ego-identity(subfactors ; ego-group, ego-affect, self-achievement)' 'self-confidence' 'ego-career' 'gender-identity' 'anticipation of achievement' and 'altruism', and in female:'ego-identity(subfactors ; ego-affect, ego-group)' 'ego-career' 'integrity' 'gender-identity' 'altruism' and 'trust'. 2. The blind, and deaf-mute adolescents, regardless of their sex, had a lower level of development in overall identity than the normal students. 3. Among the male blind adolescents, the subjective difficulties in life and subjective feelings about handicap variables were the most influential to the level of development of overall identity and strongly influenced the strength of the 'ego-identity' 'ego-career' and 'altruism' factors. Secondly, the family expectations of subject and teacher's educational practice were less influential variables but still strongly influential in forming levels of identity. 4. Among the female blind adolescents the teacher's educational practice was the most influential to the level of development for all factors of identity except 'gender-identity' and 'altruism'. Subjective feelings about handicap strongly influenced the formation of all factors of identity, on the other hand, the objective evaluation of seriousness of handicap did least to form the level of development of identity, especially 'gender-identity'. After subjective feelings about handicap, age upon becoming handicapped was the second strongly influential factor in the formation of 'gender-identity'. The 'integrity' factor, which was unique to the female group, was least influenced by family expectations about subject. 'Trust', on the other hand, which was also unique to the female group, was greatly influenced by family expectations about subject. 5. Among the male deaf-mute adolescents, the teacher's educational practice and subjective difficulties in life were the most influential variables on the overall developmental level of identity and on all of its subcategories. The objective evaluation of seriousness of handicap was also strongly influential to the level of development of not all but many factors. 6. In the female deaf-mute adolescent group, the objective evaluation of seriousness of handicap was the most strongly influential of the variables to the development of overall identity. The teacher's educational practice had a strong influence on the developmental level of 'ego-identity' 'ego-affect' and 'integrity' factors. It should be stressed the age upon becoming handicapped variable had a strong negative correlation with the developmental level of identity. Thus the younger the age upon becoming handicapped, the higher the development of identity. Among the female deaf-mute adolescents, the subjective feelings about handicap and the age upon becoming handicapped variables were not so influential to the development of identity. 7. The seven tested personal and environmental variables of blind, and deaf-mute subjects showed significant influence in the formation of identity. The variables significantly influenced the developmental levels of the total identity, 'ego-career' and 'ego-group' in both male and female blind, and deaf-mute groups. And the variables also influenced levels of 'self-confidence' and the 'anticipation of achievement' among the male blind and the male deaf-mute, and influenced the self-perceived 'integrity' of both female handicapped groups. Among the male and female deaf-mute the variables were greatly contributory to the development of overall identity and to each of its subfactors. Each of the personal and environmental variables was also contributory to the developmental level of the different handicapped groups ; teacher's educational practice was influential to the blind, and the deaf-mute among males and females ; subjective difficulties in life was influential to the male blind, and the deaf-mute ; family expectations of subject was influential to the male blind ; age upon becoming handicapped and subjective feeling about handicap exerted influence on the development of identity of the female deaf-mute ; and the objective evaluation was influential to that of the deaf-mute among either males and females, but age starting education was least contributory to their identity.

학생청소년의 불안성향과 문제행동 유형간의 상관분석

김헌수,이재우,나철,김영돈,김민호,김은희,권지란,박광식,이길홍,민병근 중앙대학교 의과대학 의과학연구소 1987 中央醫大誌 Vol.12 No.4

The purpose of the present study was to examine the relationship between their problem behavioral pattern and anxious trends among Korean student adolescent. Zung's measurement of anxiety level undergone through used of the self-rating anxiety scale. the data were collected through the questionaire survey which was conducted on Dec.1, 1983. Subjects served for this atudy consisted of 1,404 syudents in Korea, randomly sampled from Korean student population by means of census method. The data were analysed by CDC-174 computer of KAIST, using SPSS pogram. Statistical methods empoyed were χ^2 test and Eta measures. the results of this study were as follows. 1. It showed that students psychological anxious trends had greatest significant correlation with adolescent student's problem brhavioral pattern, but the cardiovascular, respiratory, gastrointestional and genitourinary anxious trends has not significantly related with student's problem behavioral pattern. 2. Students group with undersocialized aggressive, undersocialized nonaggressive,undersocialized school-norm avoidant, or socialized nonaggressive behavioral patterns were less anxious, whereas those with socialized latent aggressive, socialized sexual, or socialized modellong behavioral patterns were higher anxious.

위절제술 환자의 표준진료지침 개발 및 적용 효과

김은희,김철규,이순교,김순덕,이혜옥,권정순,이경미,이민미,심순미,유용만,신종식,강은희,이상일,김병식,오성태,육정환,박수길 한국의료QA학회 2003 한국의료질향상학회지 Vol.10 No.2

Background : Gastric cancer is the most common malignant tumor in Korea. surgical operation is one of the major treatment modalities for gastric cancer patients. Therefore, gastrectomy is one of the most common procedures in General Surgery. There were variation in length of hospital stay and medical treatment for gastrectomy between three surgeons at Asan Medical Center. Clinical pathways have received considerable attention as a tool for recucing the medical practice variation, increasing the efficiency of care process, and improving the quality of care. The aim of this study was to evaluate the effect of a clinical pathway for gastrectomy in gastric cancer patients. Methods : The clinical pathway for gastrectomy was developed and implemented by a multidisciplinary group in Asan Medical Center. A computerized clinical pathway program was developed and revised after a pilot test. A total of 145 patients underwent gastrectomy by three surgeons at Asan Medical Center. We compared the length of hospital stay, patient satisfaction, and unplanned readmission rate between the pre-pathway group(n=67) and the post-pathway group(n=78). We also investigated the degree of satisfaction among the physicians and nurses who were main end-users of the clinical pathway. Results : The clinical pathway was applied to all target patients. The average length of hospital stay was shortened from 12.7days to 10.6days(p<0.01). The degree of patient satisfaction with the care process changed from 90.3% to 89.2% after the implementation of the clinical pathway, but the difference was of satistically significant(p=0.761). Unplanned readmission rate was 2.9% in the pre-pathway group. More than 90% of physicians and nurses answered that the clinical pathway had been a useful tool in their medical practice. Conclusions : The findings of the study demonstrated that implementation of the clinical pathway for gastrectomy produced substantial reduction in the length of hospital stay while improving the quality of patient outcomes. The computerized clinical pathway program can be used as one of the powerful patient management tools for reducing the practice variations and increasing the efficiency of care process in Korea hospital settings.

Synthesis and characterization of enantiopure copper(<small>II</small>) complexes using chiral bidentate ligands

Min, Kil Sik,Park, A Hyun,Shin, Jong Won,Rowthu, Sankara Rao,Kim, Seog K.,Ryoo, Jae Jeong Royal Society of Chemistry 2010 Dalton transactions Vol.39 No.37

<P>Chiral copper(<SMALL>II</SMALL>) complexes of the types [Cu<SUP>II</SUP>(<I>R</I>/<I>S</I>-ppme)<SUB>3</SUB>](ClO<SUB>4</SUB>)<SUB>2</SUB> and [Cu<SUP>II</SUP>(<I>R</I>/<I>S</I>-ppme)<SUB>2</SUB>(SO<SUB>4</SUB>)] have been synthesized by reactions of Cu(ClO<SUB>4</SUB>)<SUB>2</SUB>·6H<SUB>2</SUB>O and CuSO<SUB>4</SUB>·5H<SUB>2</SUB>O with <I>R</I>/<I>S</I>-ppme in methanol under aerobic conditions (<I>R</I>/<I>S</I>-ppme = (<I>R</I>/<I>S</I>)-(±)-1-phenyl-<I>N</I>-(pyridine-2-ylmethylene)ethanamine). All complexes were isolated and characterized by X-ray crystallography and circular dichroism (CD): (Λ)-[Cu<SUP>II</SUP>(<I>R</I>-ppme)<SUB>3</SUB>](ClO<SUB>4</SUB>)<SUB>2</SUB> (<B>1</B>), (Δ)-[Cu(<I>S</I>-ppme)<SUB>3</SUB>](ClO<SUB>4</SUB>)<SUB>2</SUB>·H<SUB>2</SUB>O (<B>2</B>), (Δ)-[Cu<SUP>II</SUP>(<I>R</I>-ppme)<SUB>2</SUB>(SO<SUB>4</SUB>)]·4CH<SUB>3</SUB>OH (<B>3</B>), and (Λ)-[Cu<SUP>II</SUP>(<I>S</I>-ppme)<SUB>2</SUB>(SO<SUB>4</SUB>)]·4CH<SUB>3</SUB>OH (<B>4</B>). <B>1</B> and <B>2</B> with ClO<SUB>4</SUB><SUP>−</SUP> anions are formed as tris(<I>R</I>/<I>S</I>-ppme) copper(<SMALL>II</SMALL>) complexes, while <B>3</B> and <B>4</B> with SO<SUB>4</SUB><SUP>2−</SUP> are formed as bis(<I>R</I>/<I>S</I>-ppme) copper(<SMALL>II</SMALL>) complexes. The structures of <B>1</B> with <I>R</I>-ppmes and <B>4</B> with <I>S</I>-ppmes show the same absolute configurations (Λ). In contrast, <B>2</B> with <I>S</I>-ppmes and <B>3</B> with <I>R</I>-ppmes exhibit Δ configurations. In the electron paramagnetic resonance (EPR) spectra of <B>1</B> and <B>3</B>, both compounds demonstrate <I>z</I>-axis elongated structures. The CD spectra of <B>1</B> and <B>2</B> show Cotton effects in an enantiomeric pattern; those of <B>3</B> and <B>4</B> also display the same effects.</P> <P>Graphic Abstract</P><P>Complexes <B>1</B> and <B>2</B> are coordinated by three <I>R</I>/<I>S</I>-ppme ligands, in which they form distorted octahedral structures. The structures of <B>1</B> and <B>2</B> display Λ and Δ configurations, respectively. The CD spectra of <B>1</B> and <B>2</B> exhibit Cotton effects in an enantiomeric pattern. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0dt00380h'> </P>

Observation of Redox-Induced Electron Transfer and Spin Crossover for Dinuclear Cobalt and Iron Complexes with the 2,5-Di-<i>tert</i>-butyl-3,6-dihydroxy-1,4-benzoquinonate Bridging Ligand

Min, Kil Sik,DiPasquale, Antonio G.,Rheingold, Arnold L.,White, Henry S.,Miller, Joel S. American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.17

<P>Dinuclear [(TPyA)M(II)(DBQ(2-))M(II)(TPyA)](BF(4))(2) [TPyA = tris(2-pyridylmethyl)amine; DBQ(2-) = 2,5-di-tert-butyl-3,6-dihydroxy-1,4-benzoquinonate; M = Co (1(2+)), Fe (2(2+)), Ni (3(2+))] complexes have been prepared by the reaction of M(2+), TPyA, H(2)DBQ, and triethylamine in MeOH solution. Their monooxidized form [(TPyA)M(III)(DBQ(*3-))M(III)(TPyA)](3+) [Co = (1(3+)), Fe (2(3+))] has been synthesized by using ferrocenium tetrafluoroborate, and the dioxidized form of 1(2+), [(TPyA)Co(III)(DBQ(2-))Co(III)(TPyA)](4+) (1(4+)), has been obtained by using thianthrinium tetrafluoroborate. These dinuclear compounds were characterized by X-ray crystallography, electrochemistry, magnetism, and EPR spectroscopy. Valence ambiguous 1(3+) forms via redox-induced electron transfer, whereby the one-electron oxidation of the [Co(II)(DBQ(2-))Co(II)](2+) core forms [Co(III)(DBQ(*3-))Co(III)](3+), and it also exhibits spin crossover behavior to the core [Co(III)(DBQ(2-))Co(II)](3+) above room temperature. The M ions in 1 and 2 have a distorted octahedral geometry by coordination with four nitrogens of a TPyA, two oxygens of a DBQ(2-/*3-). Due to the interdimer offset face-to-face pi-pi and/or herringbone interactions, 1(2+), 1(3+), and 2(2+) show extended 1-D and/or 2-D supramolecular structures. The existence of DBQ(*3-) in 1(3+) is confirmed from both solid-state magnetic and solution EPR data. Co- and Ni-based 1(2+) and 3(2+) show weak antiferromagnetic interactions [1(2+): g = 2.44, J/k(B) = -3.20 K (-2.22 cm(-1)); 3(2+): g = 2.13, J/k(B) = -3.22 K (-2.24 cm(-1)), H = -2JS(1)*S(2) for 1(2+) and 3(2+)], while Fe-based 2(2+) exhibits strong spin crossover behavior above room temperature. 1(2+) has three reversible one-electron transfer waves at E(1/2) (vs SCE in MeCN) = -1.121, 0.007, and 0.329 V, and a fourth wave at -1.741 V that exhibits a slight chemical irreversibility. The first three correspond to [Co(II)DBQ(2-)Co(II)](2+) reduction to [Co(II)DBQ(*3-)Co(II)](+), and oxidation to [Co(III)DBQ(*3-)Co(III)](3+) and [Co(III)DBQ(2-)Co(III)](4+), respectively. The mechanism of the multielectron transfer oxidation from [Co(II)DBQ(2-)Co(II)](2+) to [Co(III)DBQ(*3-)Co(III)](3+) is unknown; the energy of stabilization for oxidizing the Co(II) centers in the presence of DBQ(*3-), relative to oxidizing the Co(II) centers in the presence of DBQ(2-) is computed to be 1.45 eV. 2(2+) also has three reversible one-electron transfer waves at 0.802, 0.281, and -1.007 V that correspond to two successive one-electron oxidations (2(2+)/2(3+) and 2(3+)/2(4+)), and a one-electron reduction (2(2+)/2(+)). 2(2+) has the [Fe(hs)(II)(DBQ(2-))Fe(hs)(II)](2+) electronic structure that becomes [Fe(hs)(III)(DBQ(*3-))Fe(hs)(III)](3+) upon oxidation. The latter undergoes spin crossover above room temperature to populate the [Fe(hs)(III)(DBQ(2-))Fe(hs)(II)](3+) excited state.</P>

Stretchable graphene conductor based on fluid dynamics and its application to flexible conductometric sensor

Kil Min Sik,Park Hong Jun,Yoon Jo Hee,Jang Jinwu,Lee Kyoung G.,Choi Bong Gill 한국탄소학회 2022 Carbon Letters Vol.32 No.7

A facile and efficient method was developed to prepare highly stretchable and conductive graphene conductors with wrinkled structures by the mechanical stretching and shrinking of elastomeric substrates, in which graphene inks were printed on a prestretched elastomeric substrate. Stretchable and exfoliated graphene inks were prepared by mixing graphite and Ecoflex in a shear-assisted fluid dynamics reactor. The resultant graphene conductor exhibited excellent stretchability at 150% strain and high electrical conductivity of 64 ± 1.2 S m−1. The resistance of the conductor did not change in bent, twisted, and stretched states. The resistance did not change during 10,000 cycles of stretching/releasing, with a maximum strain of 150%. Based on the graphene conductor, a stretchable conductometric sensor with a two-electrode configuration was fabricated to measure impedance changes at different concentrations of electrolyte ions. This sensor exhibited a good and linear sensitivity curve (298.61 Ω mM−1, R2 = 0.999) in bent and stretched states.

나피온 폴리머를 이용한 금 전극의 표면 개질 및 이의 삼투압 측정용 임피던스 센서 응용

길민식 ( Min Sik Kil ),김민재 ( Min Jae Kim ),윤조희 ( Jo Hee Yoon ),장진우 ( Jinwu Jang ),이경균 ( Kyoung G. Lee ),최봉길 ( Bong Gill Choi ) 한국공업화학회 2023 공업화학 Vol.34 No.1

본 논문에서는 용액의 이온 농도 측정이 가능한 나피온 폴리머(Nafion polymer) 코팅 기반 2상 금 전극의 임피던스(Impedance) 센서를 개발하였다. 스퍼터링(Sputtering) 공정을 통해서 제작된 금 전극의 표면을 나피온 폴리머를 사용하여 표면 개질 하였다. 상기 제작된 전극은 분극 현상 제어가 가능하여 전기화학적 신호를 안정적으로 측정할 수 있도록 하였다. 분광학과 전자주사현미경 관찰을 통하여 박막의 나피온 폴리머 코팅을 확인하였다. 나피온 코팅이 된 전극은 기존 금 전극에 비해 안정적인 임피던스 신호를 보여 주었으며, 표준 염화나트륨(NaCl) 용액 사용 시 임피던스 센서의 신뢰성 높은 검정 곡선(R² = 0.983)을 나타내었다. 또한, 임피던스 센서는 상용화 전도도 장치와 인공 눈물의 이온 농도 측정 비교 실험을 진행하였으며, 유사한 결과값을 확인하였다. In this work, we developed a Nafion polymer-coated impedance sensor with two gold electrode configurations to measure the ion concentration in solution samples. The gold electrodes were fabricated through the sputtering process, followed by surface modification using Nafion polymer. The resulting sensors enable the prevention of the polarization phenomenon on the electrode surface, resulting in stable measurement of electrochemical signals. Spectroscopy and scanning electron microscopy measurements revealed that the thin film of Nafion was coated uniformly onto the surface of the gold electrode. The Nafion-coated sensor exhibited more stable impedance signals than the conventional gold electrode. It showed a highly reliable calibration curve (R² = 0.983) of the impedance sensor using a standard sodium chloride solution. In addition, a comparison experiment between the impedance sensor and a commercial conductivity sensor was performed to measure the ion concentration of artificial tears, showing similar results for the two sensors.

스크린 프린팅 탄소 전극의 이리듐 산화물 표면 개질과 이의 임피던스 센서 응용

길민식 ( Min Sik Kil ),윤조희 ( Jo Hee Yoon ),장진우 ( Jinwu Jang ),최봉길 ( Bong Gill Choi ) 한국공업화학회 2023 공업화학 Vol.34 No.5

본 연구에서는 스크린 프린팅 공정을 통해 탄소 잉크 기반의 2상 전극을 제작하고, 전극 표면에 이리듐 산화물(IrO_x)을 코팅함으로써 전극의 분극 현상을 제어할 수 있는 임피던스 센서를 개발하였다. IrO_x는 순환 전압 전류법으로 탄소전극의 표면 위에 순환 수(0~50 cycles)에 따라서 코팅되었다. 전자주사현미경을 이용하여 cycle 수가 증가할수록 IrO_x입자의 크기와 수가 증가하는 경향성을 확인하였다. 전기화학 임피던스 분석을 이용하여 상기 제조된 센서들의 NaCl 농도에 따른 임피던스 변화 값을 조사하였다. 50 cycle에서 제조된 센서가 가장 우수한 결정계수와 재현성을 나타내었으며, 이는 분극 현상이 잘 제어되었기 때문이다. 실제 용액 샘플들을 이용한 삼투압 장비와 비교 측정 실험을 수행함으로써 IrO_x 기반 센서의 안구건조증 진단 센서로의 활용가치를 증명하였다. In this study, we developed an impedance sensor capable of controlling electrode polarization by coating iridium oxide (IrO_x) on the surface of the screen-printed carbon electrode. IrO_x was deposited on the surface of carbon electrodes according to the number of cycles (0~50 cycles) by cyclic voltammetry. Observation of scanning electron microscope images revealed that the size and number of IrO_x particles increased as the number of cycles increased. The changes in impedance responses as a function of the NaCl concentration of the as-obtained sensors were investigated using electrochemical impedance spectroscopy. The sensors manufactured in 50 cycles exhibited the best coefficient of determination and reproducibility, attributed to the well-controlled electrode polarization. We further demonstrated the usefulness of the IrO_x-based sensor as a diagnosis sensor for dry eye syndrome by comparing the results of the commercially available osmometer and our sensor using actual solution samples.