A Fully Integrated Paper-Microfluidic Electrochemical Device for Simultaneous Analysis of Physiologic Blood Ions.

A fully integrated paper microfluidic electrochemical device equipped with three different cation permeable films is developed to determine blood ions (Cl-, Na⁺, K⁺, and Ca2+) at a time. These blood ions that are normally dissolved in the real human blood stream are essential for cell metabolisms and homeostasis in the human body. Abnormal concentration of blood ions causes many serious disorders. The optimized microfluidic device working without any external power source can directly and effectively separate human blood components, and subsequently detect a specific blood ion with minimized interference. The measured sensitivity to Cl-, K⁺, Na⁺, and Ca2+ are -47.71, 45.97, 51.06, and 19.46 in mV decade-1, respectively. Potentiometric responses of the microfluidic devices to blood serum samples are in the normal ranges of each cation, and comparable with responses from the commercial blood ion analyzer Abbott i-Stat.

Investigation of aging effects in human hair using atomic force microscopy.

BACKGROUND: A thorough characterization of the morphological structure and physical properties is essential for an understanding of human hair. A number of techniques such as scanning electron microscopy, transmission electron microscopy and confocal microscopy have been used to study hair surfaces. Recently, atomic force microscopy (AFM) has emerged as an ideal method for the non-invasive examination of hair surfaces. PURPOSE: To investigate the effects of aging on normal Korean hair diameter and surface features using AFM. METHODS: We enrolled 60 Korean volunteers of various ages who had no hair diseases. We analyzed hair diameter, AFM images of the hair surface, cuticular descriptors and micro-scale mechanical properties for their associations with aging. RESULTS: Hair diameter was found to increase for the first 20-30 years of life, after which it began to decrease. AFM images of most of the younger subjects showed typical step-like topographic properties with clear scale edges. The AFM images of most of the older subjects revealed dilapidated structures, poorly demarcated scale edges and undulated surfaces. Among the cuticular descriptors, surface roughness increased significantly with age. Force to distance analysis demonstrated a dependence on age. CONCLUSION: These results suggest that aging causes changes in hair diameter and surface structure.