• Journal of Sensor Science and Technology
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• v.27 no.2
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• pp.69-75
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• 2018

In this study, we propose a multichannel interdigitated capacitor (IDC) sensor for detecting the bitterness of coffee. The operating principle of the device is based on the variation in capacitance of a sensing membrane in contact with a bitter solution. Four solvatochromic dyes, namely, Nile red, Reichardt's dye, auramine-O, and rhodamine-B, were mixed with polyvinylchloride (PVC) and N,N-dimethylacetamide (DMAC), to create four different types of bitter-sensitive solutions. These solutions were then individually inserted into four interdigitated electrodes (IDEs) using a spin coater, to prepare four distinct IDC sensors. The sensors are capable of detecting bitterness-inducing chemical compounds in any solution, at concentrations of approximately $1{\mu}M$ to 1 M. The sensitivity of the IDC bitterness sensor containing the Reichardt's dye sensing-membrane was approximately 1.58 nF/decade. The multichannel sensor has a response time of approximately 6 s, and an approximate recovery time of 5 s. The proposed sensor offers a stable sensing response and linear sensing performance over a wide measurement range, with a correlation coefficient ($R^2$) of approximately 0.972.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.38-39
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• 2006

In this paper, we describe a method of accurate modeling capacitor in Low Temperature Co-fired Ceramic(LTCC). We obtain building blocks that present characterization of test structure through partial element equivalent circuit (PEEC) method. The extracted model of building blocks can be used for predicting behaviors of capacitors with different geometries. This method can provide the good inspection of capacitor to device engineer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.616-619
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• 2003

This work presents the design, fabrication and microwave performance of distributed analog phase shifter (DAPS) fabricated on $(Ba,\;Sr)TiO_3$ (BST) thin films for X-band applications. Ferroelectric BST thin films were deposited on MgO substrates by pulsed laser deposition. The DAPS consists of high impedance coplanar waveguide (CPW) and periodically loaded tunable BST interdigitated capacitors (IDC). In order to reduce the insertion loss of DAPS and to remove the alteration of unloaded CPW properties according to an applied dc bias voltage, BST layer under transmission lines were removed by photolithography and RF-ion milling. The measured results are in good agreement with the simulated results at the frequencies of interest. The measured differential phase shift based on BST thin films was $24^{\circ}$ and the insertion loss decreased from 1.1 dB to 0.7 dB with increasing the bias voltage from 0 to 40V at 10 GHz.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.12
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• pp.769-775
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• 2016

Characteristics of a wireless sensor powered by the IDE (interdigitated electrode) embedded piezoelectric cantilever generator were analyzed in order to evaluate its potential for use in wireless sensor applications. The IDE embedded piezoelectric cantilever was designed and fabricated to have a self-resonance frequency of 126 Hz and acceleration of 1.57 G, respectively, for the mechanical resonance with a practical conveyor system in a thermal-power plant. It produced maximum output power of 2.81 mW under the resistive load of $160{\Omega}$ at 126 Hz. The wireless sensor module is electrically connected to a rectifier capacitor with capacity of 0.68 farad and 3.8 V for power supply by the piezoelectric cantilever generator. The unloaded capacitor could be charged as a rate of approximately $365{\mu}V/s$ while the capacitor exhibited that of 0.997 mV/min. during communication under low duty cycle of 0.2%. Therefore, it is considered that the fabricated IDE embedded piezoelectric cantilever generator can be used for wireless sensor applications.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1090-1095
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• 2003

In this paper, the modeling and design of high-Q multilayer passives and multilayer diplexer for GSM/DCS applications designed and fabricated using these passives have been investigated.. To miniaturize the system, configurations of inductor and capacitor have involved a square spiral structure and a vertically-interdigitated capacitor similar to 3D interdigital structure, respectively. Multilayer diplexers for GSM/DCS applications were designed and fabricated to apply high-Q multilayer passives to practical systems, which were designed by the proposed structural and equivalent circuit model. LPF for GSM band had the passband insertion loss of less than 0.55 dB, the return loss of more than 12 dB, and the isolation level of more than 26 dB by locating attenuation pole at 1800 MHz. HPF for DCS band had the passband insertion loss of less than 0.82 dB, the return loss of more than 11 dB, and the isolation level of more than 38 dB by locating attenuation pole at 930 MHz.