• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.5
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• pp.747-752
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• 1987

Analysis and design procedures for both symmetrical and non-symmetrical open-circuited interdigital multiple coupled microstrip line structures for applications as wide-band DC blocks/filters have been presented. The design equations, as is the case of other microstrip structures, are based on a simplified TEM model. The experimental results are in good agreement with the theoretically predicted ones.

• Journal of Biosystems Engineering
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• v.41 no.1
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• pp.60-65
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• 2016

Purpose: The necessity for precise manipulation of bioparticles has greatly increased in the fields of bioscience, biomedical, and environmental monitoring. Dielectrophoresis (DEP) is considered to be an ideal technique to manipulate bioparticles. The objective of this study is to develop a DEP microfluidic device that can trap fluorescent beads, which mimic bioparticles, at the low voltage and frequency of the sinusoidal signal supplied to the microfluidic device. Methods: A DEP microfluidic device, which is composed of polydimethylsiloxane (PDMS) channels and interdigitated electrode networks, is fabricated to trap fluorescent beads. The geometry of the interdigitated electrodes is determined through computational simulation. To determine the optimum voltage and frequency of the sinusoidal signal supplied to the device, the experiments of trapping beads are conducted at various combinations of voltage and frequency. The performance of the DEP microfluidic device is evaluated by investigating the correlation between fluorescent intensities and bead concentrations. Results: The optimum ratio of the widths between the negative and positive electrodes was 1:4 ($20:80{\mu}m$) at a gap of $20{\mu}m$ between the two electrodes. The DEP electrode networks were fabricated based on this geometry and used for the bead trapping experiments. The optimum voltage and frequency of the supplied signal for trapping fluorescent beads were 15 V and 5 kHz, respectively. The fluorescent intensity of the trapped beads increased linearly as the bead concentration increased. The coefficient of determination ($R^2$) between the fluorescent intensity and the bead concentration was 0.989. Conclusions: It is concluded that the microfluidic device developed in this study is promising for trapping bioparticles, such as a cell or virus, if they are conjugated to beads, and their concentration is quantified.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1298-1302
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• 2011

This study describes the development of an electrochemical array immunochip for the detection of IgG. Interdigitated immunochip platforms were fabricated by sputtering gold on a glass wafer by using MEMS process and then were coated with Eudragit S100, an enteric polymer, forming an insulating layer over the working area of immunochips. The breakdown of the polymer layer was exemplified by the catalytic action of urease which, in the presence of urea, caused an alkaline pH change. This subsequently caused an increase of the double layer capacitance of the underlying electrode. Used in conjunction with a competitive immunoassay format, this allowed the ratio of initial to final electrode capacitance to be directly linked with the concentration of analyte, i.e. IgG. Responses to IgG could be detected at IgG concentration as low as $250\;ngmL^{-1}$ and showed good linearity up to IgG concentration as high as $20\;{\mu}gmL^{-1}$.

• Korean Journal of Materials Research
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• v.9 no.9
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• pp.890-895
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• 1999

The recent important issue in solar cell fabrication is to adopt thin film silicon solar cells on cheap substrates. However, thin cells demand new grid design concept that all the contacts(to the emitter and base) be located on the front surface. Hence, the aim of the investigation presented in this paper was to determine the potential and the basic limitation of the design. With this concept, an interdigitated front grid structure was realized and cells were fabricated through a set of photolithography processes. Confirmed efficiencies of up to 11.5% were achieved on bonded SOI wafers with a cell thickness of 50$\mu\textrm{m}$ in the case of finger spacing more than $\mu\textrm{m}$ and a base width of 35$\mu\textrm{m}$. It was also shown from the results that the design rules for optimizing the base fraction and reducing the shadowing fraction are noted as an important technique to realize high-efficiency thin silicon solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.8
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• pp.501-507
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• 2017

A unimorph piezoelectric cantilever generator with an interdigitated electrode (IDE) was developed for vibration energy harvester applications driven in the longitudinal mode. Hard lead zirconate titanate (PZT) ceramic with a high $Q_m$ of 1,280 was used as the piezoelectric active material. Ten PZT sheets produced by tape casting were laminated and co-fired with an Ag/Pd IDE at $1,050^{\circ}C$ for 2 h. The approximately $280{\mu}m$-thick co-fired PZT laminate with the IDE was attached to a stainless steel substrate with an adhesive epoxy for the fabrication of an IDE unimorph cantilever. Its energy harvesting characteristics were evaluated: an output power of $1.1{\mu}W$ at 120 Hz across the resistive load of $700k{\Omega}$ was obtained, corresponding to a normalized power factor of $4.1{\mu}W/(G^2{\cdot}cm^3)$.

• Journal of Mechanical Science and Technology
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• v.20 no.4
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• pp.505-512
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• 2006

This paper presents an integrated multifunctional sensor based on MEMS technology, which can be used or embedded in mobile devices for environmental monitoring. An absolute pressure sensor, a temperature sensor and a humidity sensor are integrated in one silicon chip of which the size is $5mm\times5mm$. The pressure sensor uses a bulk-micromachined diaphragm structure with the piezoresistors. For temperature sensing, a silicon temperature sensor based on the spreading-resistance principle is designed and fabricated. The humidity sensor is a capacitive humidity sensor which has the polyimide film and interdigitated capacitance electrodes. The different piezoresistive orientation is used for the pressure and temperature sensor to avoid the interference between sensors. Each sensor shows good sensor characteristics except for the humidity sensor. However, the linearity and hysteresis of the humidity sensor can be improved by selecting the proper polymer materials and structures.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.2867-2872
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• 2012

SAN/$BMIPF_6$ nanofibers were fabricated by an electrospinning process and used as chemiresistors for sensing alcohol vapours. A hydrophobic and air-stable ionic liquid, $BMIPF_6$, was used to impart electrical conductivity to insulating SAN nanofibers. The effects of $BMIPF_6$ addition on the morphology of the nanofibers were explained in terms of surface tension, viscosity and conductivity. After exposing the SAN/$BMIPF_6$ nanofibers collected on an interdigitated electrode to alcohol vapours (ethanol, 1-propanol and 1-butanol), the resistance of the nanofibers decreased due to adsorption of alcohol molecules. The electrospun SAN/$BMIPF_6$ nanofibers sensor exhibited good sensitivity and reproducibility.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.9-12
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• 2005

Recently, research on the morphing wing is an interesting issue to develop the capability of the wing such as improving the lift and reduction of drag during the operation of an aircraft by changing the wing shape from one configuration to another. A more efficient weight reduction of the wing using smart or morphing wing concept can be achieved in comparison with the conventional flaps. In this study, it is investigated the behaviors of the morphing wing using Macro Fiber Composite (MFC) actuators. Generally, MFC is the piezocomposite actuator with the rectangular PZT fiber and epoxy matrix, and uses the interdigitated electrode to produce more powerful actuation in the in-plane direction. Furthermore, it can produce the twisting actuation as compared with the traditional PZT actuators. In the formulation, the first-order shear deformation plate theory is used, and finite element method is adopted in the numerical analysis of the model. Results show the characteristics of the static behavior of the morphing wing according to the change of the actuation voltage.

• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.292-297
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• 2004

Carbon nanotubes (CNT) were synthesized by arc-discharge method. To fabricate CNT sensor, CNT powder was dispersed in ${\alpha}$-Terpinol($C_{10}H_{17}OH$) solution. The CNT tilms were fabricated by screen printing method on the interdigitated Pt/Pd alloy electrode. The microstructure of CNT film was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In order to investigate the gas sensing characteristics of the film, the CNT film was experimented to measure NO response and recovery time. The CNT sensor with a heater was compared to that without a heater. And this sensor shows better reproductibility and faster recovery time than another CNT sensors. We suggest the possibility to utilize a CNT as new sensing materials for environmental monitoring.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.1 s.244
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• pp.1-7
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• 2006

A system for the electrical bio signal detection for a microchip is proposed. Gold nanoparticles were selected for the system for their bio-compatibility and potential for higher sensitivity with large surface areas. For the estimation of the conductivity of gold nanoparticles, microchips with interdigitated microelectrodes of 3,5,7 and $9\;{\mu}m$ spacing were fabricated. In addition, a simulation program was developed to estimate the electrical resistance of the fabricated microchip. The results of conduction simulation for the nanoparticles show good agreements with experimental data, which validate the proposed system.