| 摘要 |
<p>An inexpensive device is provided for sensing the moisture content of soil, particularly around house plants. The device has a dark colored background with a thin, permeable hydrophilic film in front of it. The film is protected by a transparent plastic layer in front and the assembly is heat sealed together. A hole is pierced through the protective layer for giving the permeable film access to soil moisture. The permeable film is preferably a sheet of light colored, single ply facial or toilet tissue which has high reflectivity and low transmission of light when dry but which becomes quite translucent when wet. The extent of dark colored background exposed by the wet film indicates soil moisture content.</p> |
