  We present a simple but effective method to measure the pressure inside a
deformable micro-channel using laser scattering in a translucent Scotch tape.
Our idea exploits the fact that the speckle pattern generated by a turbid layer
is sensitive to the changes in an optical wavefront of an impinging beam. A
change in the internal pressure of a channel deforms the elastic channel, which
can be detected by measuring speckle patterns of a coherent laser that has
passed through the channel and the Scotch tape. We demonstrate that internal
pressure can be remotely sensed with the resolution below 0.1 kPa within a
pressure range of 3 kPa after calibration. With its high sensitivity,
reproducibility, and easy applicability, the present method will find direct
and diverse applications.
