IP Library › Granted Patent US 12667301
Granted Patent B2
US 12667301 · App. 18/428,514 · Granted Jun 30, 2026

Transepidermal water loss measurement device

Inventors: Xudong Fan (Saline, MI); Anjali Devi Sivakumar (Ann Arbor, MI)
Assignee: The Regents of The University of Michigan
A61B5/4266A61B5/681B01D53/02B01D53/266A61B2560/0252A61B2562/029B01D2257/702B01D2257/80
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Quick Facts
Patent No.
US 12667301
App. No.
18/428,514
Granted
Jun 30, 2026
Kind
B2
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.

Claims (31)

1 . A transepidermal water loss measurement device, comprising:

a housing having a measurement chamber enclosed therein, wherein the measurement chamber has an opening configured to be placed against skin of a subject;

a relative humidity sensor arranged adjacent to or in the measurement chamber and configured to measure relative humidity in the measurement chamber;

a temperature sensor arranged adjacent to or in the measurement chamber and configured to measure temperature in the measurement chamber;

an inlet duct residing in the housing and providing a first fluidic channel to the measurement chamber, wherein one end of the first fluidic channel is accessible outside of the housing and other end of the first fluidic channel connects into the measurement chamber;

an inlet valve disposed in the first fluidic channel;

an outlet duct residing in the housing and providing a second fluidic channel to the measurement chamber, wherein one end of the second fluidic channel is accessible outside of the housing and other end of the second fluidic channel is connected into the measurement chamber;

an outlet valve disposed in the second fluidic channel;

a pump fluidly coupled to the inlet duct and configured to move air through the measurement chamber; and

a controller operably couples to the pump and is in data communication with the humidity sensor and the temperature sensor, wherein the controller is configured to turn off the pump and close the inlet valve and close the outlet valve during a measurement phase, and the controller is configured to turn on the pump and open the inlet valve and open the outlet valve during a drying phase, thereby allowing the air to move through the measurement chamber.

2 . The water loss measurement device of claim 1 further comprises a first filter configured to remove moisture from the air moved by the pump into the measurement chamber.

3 . The water loss measurement device of claim 2 further comprises a second filter configured to remove hydrocarbons from the air moved by the pump into the measurement chamber.

4 . The water loss measurement device of the 1 wherein the controller is configured to determine water loss through the skin adjacent to the opening of the measurement chamber during the measurement phase.

5 . The water loss measurement device of claim 4 wherein the controller is configured to determine water loss through the skin using Fick's first and second law of diffusion.

6 . The water loss measurement device of claim 1 is configured to be worn on wrist of the subject.

7 . The water loss measurement device of claim 1 further includes means for cooling at least one of the measurement chamber and the skin of the subject.

8 . A transepidermal water loss measurement device, comprising:

a housing having a measurement chamber enclosed therein, wherein the measurement chamber has an opening configured to be placed against skin of a subject;

a relative humidity sensor arranged adjacent to or in the measurement chamber and configured to measure relative humidity in the measurement chamber;

a temperature sensor arranged adjacent to or in the measurement chamber and configured to measure temperature in the measurement chamber;

an inlet duct residing in the housing and providing a first fluidic channel to the measurement chamber, wherein one end of the first fluidic channel is accessible outside of the housing and other end of the first fluidic channel connects into the measurement chamber;

an outlet duct residing in the housing and providing a second fluidic channel to the measurement chamber, wherein one end of the second fluidic channel is accessible outside of the housing and other end of the second fluidic channel is connected into the measurement chamber;

a valve disposed in at least one or the first fluidic channel or the second fluidic channel;

a pump fluidly coupled to the inlet duct and configured to move air through the measurement chamber; and

a controller operably couples to the pump and is in data communication with the humidity sensor and the temperature sensor, wherein the controller is configured to turn off the pump and close the valve during a measurement phase, and the controller is configured to turn on the pump and open the valve during a drying phase.

9 . The water loss measurement device of claim 8 further comprises a first filter configured to remove moisture from the air moved by the pump into the measurement chamber.

10 . The water loss measurement device of claim 8 further comprises a second filter configured to remove hydrocarbons from the air moved by the pump into the measurement chamber.

11 . The water loss measurement device of the 8 wherein the controller is configured to determine water loss through the skin adjacent to the opening of the measurement chamber during the measurement phase.

12 . The water loss measurement device of claim 11 wherein the controller is configured to determine water loss through the skin using Fick's first and second law of diffusion.

13 . The water loss measurement device of claim 8 is configured to be worn on wrist of the subject.

14 . The water loss measurement device of claim 8 further includes means for cooling at least one of the measurement chamber and the skin of the subject.