Mun Yeon Jung

Fabrication of microdevices for separation of circulating tumor cell using lateral magnetophoresis and immunomagnetic nanobeads

This paper presents the design and fabrication of the microdevice for separation of circulating tumor cells (CTCs) from human whole blood based on lateral magnetophoresis principle and immunomagnetic nanobeads with the antiepithelial cell adhesive molecule (EpCAM) antibodies that selectively bind to epithelial cancer cells. We designed damascene v-shaped 60 μm-thick Nickel-Cobalt (Ni-Co) ferromagnetic wires with a flat zone and fabricated with micromachining technologies. The separation is carried out through lateral magnetophoresis, stimulated by magnetic field gradient-based isolation technologies. Experimentally, first, we observed the effect of external static magnetic intensity on the isolation rates. And we showed that microdevices isolates about 93% of the spiked CTCs cancer cells (MCF-7, a breast cancer cell line) in human whole blood at a flow rate of 40/100 μL/min with respect to human whole blood/buffer solution. For the overall isolation, it takes 15 min to process and analyze 500 μL of human whole blood.

A pocket-sized colorimetric urine reader for telemedicine in the developing countries

We have proposed a novel handheld healthcare platform, combining a pocket-sized colorimetric reader (13.5 × 6.5 × 2.5 cm3) and commercially available 10-parameter urinalysis paper strips (glucose, protein, glucose, bilirubin, urobilinogen, ketones, nitrite, pH, specific gravity, erythrocytes, and leukocytes), capable of sending data with a smart phone (Samsung electronics co., Omnia 2) using a window mobile operating system. The reader includes a novel colorimetric multi-detection module, which consists of three-chromatic light-emitting diodes (LED), silicon photodiodes (SPDs) and a novel poly(methylmethacrylate) (PMMA) optical splitter (POS). Data reading methods using conversions of the signal data (red, blue, and green) to the hue color map or the Y model data are utilized, and a curve-fitting method for the quantification is employed. The reader is battery-powered, inexpensive, light-weighing, and very speedy in analysis. And, it was applied to analyzing of a thousand of human urine samples in the Eulji university hospital and demonstrated reliable quantification of urinary glucose and protein. The features can be used by unskilled people on-site to transfer the analyzed data to experts off-site.

Novel optical absorbance-based multi-analytes detection module using a tri-chromatic LED, PDs and plastic optical fibers and its application to a palm-sized urine test strip reader

We have designed, fabricated and characterized a new palm-sized urine test strip reader (9.5 × 6.5 × 1.8 cm3) using a novel optical absorbance-based multi-analytes detecting module, consisting of a three-chromatic light-emitting diode (LED) component, photodiodes, and optical waveguide for digital readouts. The instrument is a handheld, simple but powerful in obtaining reliably a numerical analog output compatible with urine-based test strips. The proposed optical module demonstrated the excellent reading out of signal levels of proteins, glucose, blood cells, respectively, in the test urine strip kits, with low fabrication cost, rapidness, precision and reproducibility.

Ultrasensitive formaldehyde gas sensors based on a hollow assembly and its 3-dimensional network formation of single-crystalline Co3O4 nanoparticles

The detection of formaldehyde at a very low concentration is a significant research topic, because of its harmful impact on human health. In this current study, we have fabricated a hierarchical structure by the reasonable assembly of single-crystalline Co3O4 nanoparticles. A hollow morphology using sacrificial ZnO spheres could make a three-dimensional conducting network in a solid state. The resulting structure was quite active for formaldehyde sensing, and the detection limit was 50 ppb, which was nearly close to the record-high value among the other semiconducting materials. Such superior properties were attributed to the regular, hierarchically assembled structures with a small crystalline domain size, a thin hollow morphology with a large surface area, and a three-dimensional conductive network with a narrow diameter. We think that this hierarchical assembly can show great potential as a platform for improving human health through the monitoring of indoor environments.