Biomedical subjects

Sungbo Cho

Publications and source records attributed to Sungbo Cho.

3 recordsLinked to original sources

PubMed2006

Micro hole-based cell chip with impedance spectroscopy.

Electric fields can be used for the characterisation and manipulation of single biological cells. One approach to avoid the effect of electrode polarisation is to position cells on micro holes and to apply the electrical fields via the micro holes. For a correct characterisation and optimal manipulation, the electrical properties of the micro hole/cell interface must be understood. In this article, the electrical characteristics of a micro hole-based cell chip were investigated. By FEM simulation, it was estimated that the impedance measurement with micro hole-based chip is most dependent on the cell adhesion/spread rather than the intra-cellular space (contribution of intra-cellular space to the total impedance: 0.07% at 1 kHz, 0.3% at 1 MHz). The effective frequency range in which the impedance related with cell state on the hole considerably influences total measured impedance was below several kiloHertz. From the experiments, it was shown that the impedance of cell cultured on the hole at the low frequency range is increased during the increase of cultivation period, but is sensitively decreased after applying only several nanolitres of culture medium including 5% dimethlysulfoxide. This micro hole-based chip has a potential for monitoring the cell growth and the membrane integrity of even single cell without any labelling.

Biosensing Techniques↗

PubMed2006

Influence of electrode position on the characterization of artery stenotic plaques by using impedance catheter.

Use of balloon impedance catheters (BIC) for the characterization of plaques in vessels can support an optimal medical treatment of plaques. The sensitivity of impedance diagnoses with BIC is related with the distribution of electric fields determined by the electrode configuration. Using the three-dimensional finite element method (FEM) simulation, it was estimated how the relative positions of electrode array to the lipid in the vessel affect on the total impedance magnitude. Further, the short-circuiting effect was investigated with respect to the separation distance on the angular axis between the electrode arrays of angular set. By aid of FEM simulations, it is possible to design the sets of multielectrode arrays which have an optimized resolution for individual vessels.

Animals↗

PubMed2005

Design of electrode array for impedance measurement of lesions in arteries.

Use of impedance catheters can provide additional information about the composition and the morphology of early plaques in arteries. However, for a correct interpretation of the impedance data recorded inside a vessel, the extra-vessel conditions should not influence the measurement results. In this paper, we estimate the influence of the extra-vessel conditions on the impedance measurement of a vessel wall by using FEM simulation and a two-layer model. Therefore sensitivity fields are simulated. The simulations are validated by experiments and compared to analytical solutions. Further, the influence of the inner radius of a vessel on the measurement result is determined by FEM simulations. From experiments based on the two-layer model, it is found that the apparent resistance depends on the thickness of the first layer and the separation distance of the electrode structure. The measured result corresponds to the results of the FEM simulations, whereas the analytical solution assuming point electrodes is different from the measurement and simulation results. Under the assumption of homogenous and linear volume conductors, the FEM simulated distributions of sensitivity fields are determined. The inner diameter of the artery has no influence on the measurement results. The FEM simulation can support the design of electrode configuration and geometries for impedance catheters.

Animals↗