Yun-Hae Kim

Chemiresistive sensor based on polythiophene-modified single-walled carbon nanotubes for detection of NO2

In the present investigation, a chemiresistive sensor based on conducting polythiophene-modified single-walled carbon nanotubes (SWNTs) for NO2 detection has been reported. The SWNTs were aligned across 3 μm gap between two gold microelectrodes on Si/SiO2 substrate. Alignment of SWNTs was carried out by using AC dielectrophoretic technique and it was confirmed by current–voltage (I–V) measurement. Aligned SWNTs were modified by conducting polythiophene using charge controlled potentiostatic deposition and it was confirmed by field-effect transistor (FET) and electrochemical measurements. Polythiophene-modified SWNT devices were used for the NO2 detection in chemiresistive modality. This sensor exhibited very good linear response range from 10 ppb to 10 ppm.

Conducting polyaniline nanowire electrode junction

In this paper, a synthesis of conducting polyaniline nanowires electrode junction (CPNEJ) has been reported. Conducting polyaniline nanowires electrode junction on Si/SiO2 substrate (having 3 μm gap between two gold microelectrodes) is prepared. Polyaniline nanowires with diameter (ca. 140 nm to 160 nm) were synthesized by one step electrochemical polymerization using galvanostatic (constant current) technique to bridge this gap. The surface morphology of CPNEJ was studied by scanning electron microscope (SEM). The synthesized CPNEJ is an excellent platform for biosensor applications.

Glucose sensor based on conducting polyaniline nanowire electrode junction

In the present investigation, a glucose sensor based on conducting polyaniline nanowire electrode junction (CPNEJ) has been reported. The CPNEJ platform was modified by glucose oxidase by cross-linking in the presence of glutaraldehyde. The signal transduction mechanism of the sensor is based on the change in micro electrode junction conductance as a result of glucose oxidation induced change in the polymer redox state. Small size of CPNEJ sensor causes to regenerate enzyme naturally without need of redox mediators, as a result it consumes minimum amount of oxygen and also gives very fast response. This sensor exhibited good linear response range from 1 mM to 20 mM of glucose concentration with excellent sensitivity of 12 μA/mM.

Characteristics of AZO thin films prepared at various Al target input current deposited on PET substrate

Transparent conductive oxide is a thin film to be used in numerous applications throughout the industry in general. Transparent electrode materials used in these industries are in need of light transmittance with excellent high and low electrical characteristics, substances showing the most excellent physical properties while satisfying all the characteristics such as indium tin oxide film. However, reserves of indium are very small, there is an environmental pollution problem. So the study of zinc oxide (ZnO) is actively carried out in an alternative material. This study analyzed the characteristics by using a direct current (DC) magnetron sputtering system. The electric and optical properties of these films were studied by Hall measurement and optical spectroscopy, respectively. When the Al target input current is 2 mA and 4 mA, it demonstrates about 80% transmittance in the range of the visible spectrum. Also, when Al target input current was 6 mA, sheet resistance was the smallest on PET substrate. The minimum resistivity is 3.96×10-3 ohm/sq.

Localization–compensation algorithm based on the Mean kShift and the Kalman filter

In this paper, we propose a localization simulator based on the random walk/waypoint mobility model and a hybrid-type location–compensation algorithm using the Mean kShift/Kalman filter (MSKF) to enhance the precision of the estimated location value of mobile modules. From an analysis of our experimental results, the proposed algorithm using the MSKF can better compensate for the error rates, the average error rate per estimated distance moved by the mobile node (Err_ RateDV) and the error rate per estimated trace value of the mobile node (Err_RateTV) than the Mean shift or Kalman filter up to a maximum of 29% in a random mobility environment for the three scenarios.