RESUMEN
High-frequency spectroscopy (HFS) is an analytical method that is sensitive to slight changes in the dielectric properties of materials. Since water has high permittivity, HFS can be used to detect changes in water content in materials. In this study, we employed HFS to measure human skin moisture during a water sorption-desorption test. Skin without any treatment showed a resonance peak at approximately 1150 MHz. Furthermore, the peak shifted to lower frequency immediately after the application of water to the skin and gradually returned to its original frequency as time progressed. The resonance frequency obtained via least-squares fitting showed that the applied water remained in the skin after 240 s from the beginning of the measurement. These results illustrated that HFS measurements can monitor the progression of decreasing moisture content in human skin during a water sorption-desorption test.
Asunto(s)
Piel , Agua , Humanos , Piel/química , Análisis Espectral , Agua/química , Análisis de los Mínimos CuadradosRESUMEN
High-frequency spectroscopy has been applied to monitoring the stability of oil-in-water emulsions. It was found that stable emulsions showed absorption peaks at around 550 MHz; further, they shifted from lower to higher frequencies with time. The rate of increase of the frequencies was dependent on the amount of emulsifier added. These results show that the stability of emulsions can be monitored by the amount of the frequency shift.