  In this work, we present a soft capsule for mucus collection in human
intestine for diagnostic purpose, with reduced risk of tissue damage compared
with other biopsy methods. The capsule implements passive locomotion and the
sampling process is triggered by magnetic field using a permanent magnet, which
is placed on the skin above the region of interest (ROI). The capsule contains
a soft vacuum chamber which is sealed with wax. When magnetic field and mucus
are present simultaneously, the circuit inside the capsule will be closed and
nichrome wire will start to generate heat to melt the wax, and mucus will be
collected into the vacuum chamber due to air pressure. Experiments on heating
capability of nichrome wire, mucus collection and reliability of the capsule
are conducted to validate this design.
