Abstract: Transepidermal water loss (TEWL) measurement approach is presented that achieves accurate and continuous monitoring completely independent of ambient environmental variations. This new measurement approach uses short dry air purges to dry the skin surface and the water vapor collection chamber, thus refreshing the measurement site each time during skin barrier analysis. These dry air purges help maintain a highly controlled localized measuring environment without disturbing any inherent skin properties, enabling one to produce reproducible TEWL results. A mathematical model developed based on Fick's laws of diffusion is presented, and shown to have excellent agreement with the mathematical model of a commercial TEWL device. The application of this mathematical model in deciphering the TEWL values from the transient microclimate behavior in the vapor measuring chamber of the new TEWL approach is also discussed.

Abstract: A monolithic gas chromatograph is presented. The monolithic gas chromatograph includes a separation column and a gas detector. The separation column has an inlet to receive a gas sample therein. The separation column resides in a first layer of an integrated chip. The gas detector has an ionization chamber and an ionization source. The ionization chamber has an inlet in fluid communication with an outlet of the separation column to receive a gas sample from the separation column. The ionization source is configured to ionize molecules of the gas sample residing in the ionization chamber. The gas detector resides in a second layer of the integrated chip. The monolithic gas chromatograph further includes a third layer disposed between the first layer and the second layer. The third layer is configured to electrically isolate the first layer from the second layer. The gas detector is fluidly coupled to the separation column.

Abstract: Transepidermal water loss (TEWL) measurement approach is presented that achieves accurate and continuous monitoring completely independent of ambient environmental variations. This new measurement approach uses short dry air purges to dry the skin surface and the water vapor collection chamber, thus refreshing the measurement site each time during skin barrier analysis. These dry air purges help maintain a highly controlled localized measuring environment without disturbing any inherent skin properties, enabling one to produce reproducible TEWL results. A mathematical model developed based on Fick's laws of diffusion is presented, and shown to have excellent agreement with the mathematical model of a commercial TEWL device. The application of this mathematical model in deciphering the TEWL values from the transient microclimate behavior in the vapor measuring chamber of the new TEWL approach is also discussed.