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자기조립단층과 농축 기술을 이용한 저농도 내분비계 장애물질 검출용 미소유체채널 기반 전기화학 센서
김수윤(Suyun Kim),한지훈(Ji-Hoon Han),박정호(James Jungho Pak) 대한전기학회 2016 전기학회논문지 Vol.65 No.4
This paper demonstrates a microfluidic electrochemical sensor for detecting endocrine disruptor such as estradiol at a very low concentration by using preconcentration technique. In addition, self-assembled monolayer(SAM) was also employed on the working electrode of the electrochemical sensor in order to increase the estradiol capture efficiency of the sensor. SAM treatment on the working electrode enhanced the specific binding between the surface of the working electrode and the estradiol antibody. The estradiol antibody was applied on the working electrode at different concentrations(10, 20, 50, 100, 200 pg/ml) for observing the concentration dependency. The measured electrochemical redox current changed with the amount of the bound estradiol on the Au working electrode surface and the sensor can detect all the target material when the immobilized antibody amount is more than the estradiol amount in the water. The elecrochemical estradiol sensor without SAM treatment showed a low current of 7.79 nA, while the sensor treated with SAM resulted in 339 nA at 200 pg/ml, which is more than 40 fold higher output current. When combining the preconcentration technique and the SAM-treated electrode, the measured current became more than 100 fold higher than that of the sensor without neither SAM treatment nor preconcentration technique. The combination of these two techniques can would enable the proposed microfluidic electrochemical sensor to detect a very low concentration endocrine disruptor.
레이저 유도 그래핀 기반 나트륨, 칼륨 이온 선택성 전극 개발
최재성(Jaesung Choi),한지훈(Ji-hoon Han),김태헌(Taeheon Kim),박정호(James Jungho Pak) 대한전기학회 2019 전기학회논문지 Vol.68 No.7
This paper describes the development of sodium and potassium ion-selective electrodes (Na<SUP>+</SUP> and K<SUP>+</SUP> ISEs) based on laser-induced graphene (LIG), which can selectively detect sodium and potassium ions in body fluids. LIG was formed on commercial polyimide film using a computer-controlled CO2 infrared laser and was characterized by FE-SEM and Raman spectroscopy. The results show that the LIG was composed of three-dimensional randomly stacked porous graphene layers. To minimize the potential drift of the ISEs, PEDOT:PSS was electrically polymerized on LIG working electrodes using potentiometry method and EIS spectrum confirmed that the LIG/PEDOT:PSS electrode has lower charge transfer resistance than pure LIG electrode. Na<SUP>+</SUP> and K<SUP>+</SUP> ISEs were made by drop casting the ion–selective membrane cocktail over the PEDOT:PSS layer. The fabricated Na+ and K+ ISEs show high sensitivity(63.08 mV/dec, 63.80 mV/dec), low detection limit (10-5.0 M), wide linear range (10<SUP>-5</SUP> M to 10<SUP>-1</SUP> M), and excellent selectivity of Na<SUP>+</SUP> and K<SUP>+</SUP> against NH₄<SUP>+</SUP>, Mg<SUP>2+</SUP> and Ca<SUP>2+</SUP>. Combined with the advantages of a one-step processing of LIG, we expect this work to promote future applications in micro devices for commercial applications.
PdCu가 전기도금된 레이저 유도 그래핀 전극을 이용한 에탄올 효소 센서 개발
정해택(Haetaek Jeong),박상현(Sang Hyun Park),강승조(Seung-Jo Kang),박정호(James Jungho Pak) 대한전기학회 2021 전기학회논문지 Vol.70 No.2
This paper presents fabrication and characterization of an ethanol sensor whose working electrode (W.E.) is made consists of electrodeposited PdCu on laser induced graphene (LIG) layer and drop-casted alcohol oxidase (AOx) enzyme. AOx reacts with ethanol to generate hydrogen peroxide and the electrodeposited PdCu works as an electrocatalyst of hydrogen peroxide in order to increase amperometric output current. The optimum conditions for the ratio between Pd and Cu, the drop-casted AOx amount, the pH value of PBS have been obtained by varying the fabrication conditions and comparing the output results. Field emission scanning electron microscope (FE-SEM) and Raman spectroscopy were used to confirm LIG electrode formation. Also, Energy-dispersive X-ray spectroscopy (EDS) was performed to verify the ratio of the electrodeposited Pd and Cu. Cyclic voltammetry (CV) analysis of the W.E. showed that the peak reduction current occurs at –0.045 V. and this voltage was chosen as an applied voltage in amperometric measurement. Electrochemical impedance spectroscopy (EIS) shows that the charge transfer resistance of the PdCu deposited LIG W.E. is lower than the bare LIG W.E., which also shows the output current accordingly. Chronoamperometric response of the fabricated sensor was measured at various ethanol concentrations in range of 0-12 mM, and the linear sensitivity was 17.99 ㎂mM<SUP>-1</SUP>cm<SUP>-2</SUP>. which is similar or better than those of the recently reported other ethanol sensors.