• 한국의학물리학회지:의학물리
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• 제3권2호
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• pp.43-57
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• 1992

위상감지법(phase detector technique)은 세포의 막 캐패시턴스(membrane capacitance)를 실시간적으로 측정할 수 있는 유일한 방법이나 측정이 행해지는 동안 세포의 상태가 끊임없이 변화하기 때문에 피할 수 없는 측정오차가 존재한다. 본 연구는 이 오차의 근원을 분석하여 위상감지법의 실용한계를 규정하고자 하였다. 이론적 분석에 기초하여 다음과 같은 사실을 밝힐 수 있었다. 1) access conductance와 membrane conductance의 변화에 기인하는 측정오차를 줄이기 위해서는 초기 위상치를 올바로 선택하여야 한다. 2) 이 때 세포를 여기시키기 위해 인가하는 전압의 주파수를 알맞게 선택하여야 한다. 3) 그러나 초기 위상치가 정해진 이후의 위상 변화는 막 캐패시턴스의 측정에 큰 영향을 미치지 않는다. 4) 초기 위상을 적절히 선택하였다 하더라도 세포외 분비시 막 캐패시턴스가 크게 증가하는 경우에는 비례상수에 오차가 발생한다. 이 때 발생하는 오차는 측정기간 동안 비례상수를 되풀이하여(iteration) 보정함으로써 방지할 수 있다. 이상의 결과는 향후 위상감지법을 사용할 때 유용한 설용한계를 제공하리라 생각된다.

• The Korean Journal of Physiology and Pharmacology
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• 제2권1호
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• pp.95-100
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• 1998

The conductance change evoked by step depolarization was studied in primarily cultured rat adrenal chromaffin cells using patch-clamp and capacitance measurement techniques. When we applied a depolarizing pulse to a chromaffin cell, the inward calcium current was followed by an outward current and depolarization-induced exocytosis was accompanied by an increase in conductance trace. The slow inward tail current which has the same time course as the conductance change was observed in current recording. The activation of slow tail current was calcium-dependent. Reversal potentials agreed with Nernst equation assuming relative permeability of $Cs^+\;to\;K^+$ is 0.095. The outward current and tail current were blocked by apamin (200 nM) and d-tubocurarine (2 mM). The conductance change was blocked by apamin and did not affect membrane capacitance recording. We confirmed that conductance change after depolarization comes from the activation of the SK channel and can be blocked by application of the SK channel blockers. Consequently, it is necessary to consider blocking of the SK channel during membrane capacitance recording.

• 한국전기전자재료학회논문지
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• 제28권6호
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• pp.384-389
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• 2015

In this paper, we fabricated ceramic body and sapphire wafer in order to develop a hydraulic pressure sensor with high sensitivity and high temperature stability. The sapphire wafer was adopted with a membrane of capacitance ceramic pressure sensor. The capacitance value of the sensor for the finite element analysis(FEM) showed a linear pressure characteristics. Membrane was processed with a diameter of 32.4 mm and a thickness of 1 mm by using alumina powders. Ceramic body was processed with a diameter 32.4 mm and a thickness 5 mm. The capacitance pressure sensor was made with high heat treatment of the ceramic body and the sapphire wafer. Initially capacitance of the pressure sensor was 50 pF and a capacitance of 110 pF was measured from 5 bar pressure. Output voltage of 5 V was appeared at 5 bar pressure.

• 전기화학회지
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• 제13권4호
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• pp.223-234
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• 2010

본 총설에서는 캐패시터적인 특성을 가지는 다공성 전극의 전기화학특성 분석에 활용되는 임피던스의 복소캐패시턴스 분석법(complex capacitance analysis)의 이론 및 응용에 대해 정리하였다. 이론적으로 캐패시터적인 특성을 갖는 전기화학시스템에 대해 캐패시턴스허수부 도시를 활용하면 효과적인 해석이 가능함이 제시되었다. 또한, 복소캐패시턴스 분석법은 다공성 탄소 재료/전극의 EDLC 특성, 미세기공 내부의 이온전도 특성, 고분자전해질연료전지의 촉매층 이온저항 등의 분석에 효과적으로 적용될 수 있음이 검증되었다.

• 센서학회지
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• 제19권6호
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• pp.497-503
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• 2010

This paper reports a chemomechanical explosive sensor based on a thin polymer membrane. The sensor consists of thin parylene membrane and electrodes. Parylene membrane is functionalized with 4-mercaptophenol which interacts strongly with nitrotoluene based explosives. The membrane deflection caused by molecular interaction between the surface and explosives is monitored by capacitance between the membrane and the substrate. To measure the capacitance, electrodes are formed on the membrane and the substrate. While the previous cantilever system requires a bulky optical measuring system, this purely electric monitoring method offers a compact and effective system. Thus, this explosive sensor can be readily miniaturized and used in the field. The developed sensor can reliably detect dinitrotoluene and its limit of detection is evaluated as approximately 110 ppb.

• 센서학회지
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• 제28권1호
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• pp.1-6
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• 2019

This paper presents an air flow sensor (AFS) based on a polymer thin film. This AFS primarily consists of a polymer membrane attached to a metal-patterned glass substrate and a temperature-sensing element composed of NiCr. These two components were integrated on a single glass substrate. The AFS measures changes in capacitance caused by deformation of the polymer membrane based on the air flow and simultaneously detects the temperature of the surrounding environment. A readout integrated circuit (ROIC) was also fabricated for signal processing, and an ROIC chip, 1.8 mm by 1.9 mm in size, was packaged with an AFS in the form of a system-in-package module. The total size of the AFS is 1 by 1 cm, and the diameter and thickness of the circular-shaped polymer membrane are 4 mm and $15{\mu}m$, respectively. The rate of change of the capacitance is approximately 11.2% for air flows ranging between 0 and 40 m/s.

• The Korean Journal of Physiology and Pharmacology
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• 제3권5호
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• pp.471-479
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• 1999

The Kv channel activity in vascular smooth muscle cell plays an important role in the regulation of membrane potential and blood vessel tone. It was postulated that increased blood vessel tone in hypertension was associated with alteration of Kv channel and membrane potential. Therefore, using whole cell mode of patch-clamp technique, the membrane potential and the 4-AP-sensitive Kv current in cerebral arterial smooth muscle cells were compared between normotensive rat and one-kidney, one-clip Goldblatt hypertensive rat (lK,lC-GBH rat). Cell capacitance of hypertensive rat was similar to that of normotensive rat. Cell capacitance of normotensive rat and 1K,lC-GBH rat were $20.8{\pm}2.3$ and $19.5{\pm}1.4$ pF, respectively. The resting membrane potentials measured in current clamp mode from normotensive rat and 1K,lC-GBH rat were $-45.9{\pm}1.7$ and $-38.5{\pm}1.6$ mV, respectively. 4-AP (5 mM) caused the resting membrane potential hypopolarize but charybdotoxin $(0.1\;{\mu}M)$ did not cause any change of membrane potential. Component of 4-AP-sensitive Kv current was smaller in 1K,lC-GBH rat than in normotensive rat. The voltage dependence of steady-state activation and inactivation of Kv channel determined by using double-pulse protocol showed no significant difference. These results suggest that 4-AP-sensitive Kv channels playa major role in the regulation of membrane potential in cerebral arterial smooth muscle cells and alterations of 4-AP-sensitive Kv channels would contribute to hypopolarization of membrane potential in 1K,lC-GBH rat.

• 멤브레인
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• 제29권1호
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• pp.30-36
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• 2019

본 연구에서는 titanium nitride (TiN) 나노 섬유와 poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS) 전도성 고분자로 이루어진 전극과 poly(vinyl alcohol) (PVA) 기반 고분자 전해질 분리막을 이용하여 슈퍼 캐퍼시터를 제조하였다. TiN 나노 섬유의 경우 높은 전기 전도도와 이차원적 구조로 인한 스케폴드 효과를 기대할 수 있다는 점에서 전극 물질로 사용되었다. PEDOT-PSS 전도성 고분자는 수소 이온과 산화-환원 반응을 통해 보다 높은 정전용량을 나타낼 수 있으며 용액상에 분산이 용이해 유무기 복합제를 형성하기에 적합하였다. PVA 기반의 고분자 전해질 분리막은 기존의 액상의 전해질의 문제인 외부 충격에 대한 안정성을 확보할 수 있으며 염으로 사용된 $H_3PO_4$의 경우 수소 이온은 빠른 확산으로 인해 캐퍼시터의 충방전 효율에 이점이 있다. 본 연구에서 보고된 PEDOT-PSS/TiN 슈퍼캐퍼시터의 정전용량은 약 75 F/g으로 기존의 탄소기반 캐퍼시터에 비해 큰 폭으로 증가한 값이다.

• 공업화학
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• 제20권6호
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• pp.700-704
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• 2009

본 연구에서는 다공성 탄소전극의 내부 전해질 농도에 따른 전극의 전기화학적 특성 변화를 연구하였다. 다공성 탄소전극의 내부를 0.01, 0.05, 0.1, 0.5 M KCl 용액으로 채우고 양이온교환막을 결합한 후 cyclic voltammetry, chronoamperometry, impedance spectroscopy 분석을 실시하였다. 실험결과 전극의 특성은 전극 내부의 전해질 농도에 따라 큰 차이를 보였으며 농도가 높을수록 전극 내부의 charging 저항이 감소하여 전기용량이 크게 증가하는 것을 알 수 있었다. 실험결과로부터 이온교환막을 결합한 축전식 탈염공정에서 전극 내부의 전해질 농도를 높임으로써 저 농도의 염수를 효과적으로 탈염할 수 있을 것으로 기대된다.

• 센서학회지
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• 제31권6호
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• pp.366-370
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• 2022

A 12 ㎛ pixel-sized 360 × 240 microbolometer focal plane array (MBFPA) was fabricated using a complementary metaloxide-semiconductor (CMOS)-compatible process. To release the MBFPA membrane, an amorphous carbon layer (ACL) processed at a low temperature (<400 ℃) was deposited as a sacrificial layer. The thermal time constant of the MBFPA was improved by using serpentine legs and controlling the thickness of the SiNx layers at 110, 130, and 150 nm on the membrane, with response times of 6.13, 6.28, and 7.48 msec, respectively. Boron-doped amorphous Si (a-Si), which exhibits a high-temperature coefficient of resistance (TCR) and CMOS compatibility, was deposited on top of the membrane as an IR absorption layer to provide heat energy transformation. The structural stability of the thin SiNx membrane and serpentine legs was observed using field-emission scanning electron microscopy (FE-SEM). The fabrication yield was evaluated by measuring the resistance of a representative pixel in the array, which was in the range of 0.8-1.2 Mohm (as designed). The yields for SiNx thicknesses of SiNx at 110, 130, and 150 nm were 75, 86, and 86%, respectively.