Jun-Keun Chang

A novel microneedle array integrated with a PDMS biochip for microfluid systems

This paper reports a novel single-crystal-silicon microneedle array, its mechanical properties, its integration with a polydimethylsiloxane (PDMS) biochip, as well as in vitro and in vivo test results. The fabricated microneedle arrays have integrated microchannels, which are fabricated by using the processes of anisotropic dry etching, isotropic dry etching, and trench-refilling. The microchannel diameter is about 20 /spl mu/m. The 2 mm-length microneedle shaft is strong enough to endure 12.6 gf (=23.5 mN) of vertical loading. The fabricated microneedles are planar, which make it easy to integrate with biofluidic devices. As an in vitro test, the microneedle array is integrated with a PDMS biochip, and black ink is injected into a methanol-filled petri dish. The microneedle is tested in vivo by penetrating the mouse skin and precisely pricking into the small vein in the mouse tail.

Changes in oral mucosal MUC1 expression and salivary hormones throughout the menstrual cycle

OBJECTIVE To investigate relationships among oral mucosal epithelial MUC1 expression, salivary stress markers, and female gonadal hormones throughout the menstrual cycle. SUBJECTS AND METHODS Thirty healthy women (25.9 ± 2.1 years) with regular menstrual cycle were included. Unstimulated (UWS) and stimulated whole saliva (SWS) were collected during the menstrual cycle. The expression level of oral mucosal MUC1 was analyzed. 17β-Estradiol, progesterone, dehydroepiandrosterone (DHEA), cortisol, chromogranin A (CgA), and blood contamination levels were measured from UWS and SWS. RESULTS Significant positive correlations were observed between 17β-estradiol and DHEA in UWS, cortisol and CgA in UWS, MUC1 expression and DHEA in SWS, and among cortisol, progesterone, and DHEA in UWS and SWS. Significant negative correlations were observed between MUC1 and cortisol/DHEA ratio in UWS and SWS. When each phase was analyzed individually, MUC1 expression showed significant negative correlations with cortisol, progesterone, and cortisol/DHEA ratio in UWS and with progesterone and cortisol/DHEA ratio in SWS during the mid-luteal phase. A significant negative correlation was also observed between MUC1 and cortisol/DHEA ratio in UWS during the late luteal phase. CONCLUSIONS Stress-related psychoendocrinological interactions throughout the menstrual cycle resulted in a decrease in oral mucosal epithelial MUC1 expression and a weakening of oral mucosal defense.

Techniques in the Development of Endovascular Microtools & Their Applications

Endovascular is an English word meaning “within the vessel” from Latin endo (within) and vascularis (vessel) and is synonymous with intravascular. Cardiovascular refers to the interaction between the heart and the system of blood vessels from Greek cardio (heart) and Latin vascularis (vessel). In this chapter the word endovascular is used to refer to the vascular system and endovascular microtool refers to a utensil that transports substances to tissues. An endovascular microtool is designed for use in surgical operations on vascular systems that remove byproducts of metabolism, maintain the body temperature, and control the oxygen and nutrient supply. Blood flows rapidly in the vascular system. The average human male has 5 to 6 liters of blood, and blood circulates through the body in 30 seconds [78].

Chip Based Single-Column TITP (Transient Isotachophoresis) Separator

In this paper, we described transient isotachophoresis (TITP) in a highly saline solution on a polydimethylsiloxane (PDMS) chip. The ITP focusing and subsequent electrophoretic separation using a dichlorofluorescein (DCF) and fluorescein in a highly saline solution was monitored in real time using a microscope. The effect of the NaCl concentration and injection channel length were investigated. By using TITP, maximally five hundred-fold improvement in sensitivity could be achieved in microchip electrophoresis.

Radial Artery Pulse Detection System based on EIGHT Constitutional Medicine Theory

In oriental medicine, it is possible to classify each person into eight kinds of constitutions based on the eight constitutional medicine theory. We developed a piezoelectric 3-channel tactile sensor using PVDF (polyvinylidene fluoride) film for pulse detection of the radial artery. High frequency buffer (impulse buffer), amplifier, 60 Hz noise notch filter and low pass filter were integrated on three sheets of PCB board. The pulses of the radial artery at three points were checked using our system. Each constitution of the eight ones has different combinations of pulses.

Development of Serial Dilution Chip for Cellular Based Analysis

Dilution of microfluids is very complex because of the flexibility of microfluids concerned with the channel size, surface characteristics and Reynolds number. With the simulation results of dilution in microchannel, we developed the novel serial dilution chips made of PDMS and glass plate. These chips can be applied to the cell toxicity test, bacteria counting test and Minimal Inhibitory Concentration test of antibiotics and so on.