The capsule endoscope, a new application area of digital imaging, is growing rapidly but needs the versatile imaging
capabilities such as auto-focusing and zoom-in to be an active diagnostic tool. The liquid lens based on MEMS
technology can be a strong candidate because it is able to be small enough. In this paper, a cylinder-type liquid lens was
designed based on Young-Lippmann model and then fabricated with MEMS technology combining the silicon thin-film
process and the wafer bonding process. The focal length of the lens module including the fabricated liquid lens was
changed reproducibly as a function of the applied voltage. With the change of 30V in the applied bias, the focal length of
the constructed lens module could be tuned in the range of about 42cm. The fabricated liquid lens was also proven to be
small enough to be adopted in the capsule endoscope, which means the liquid lens can be utilized for the imaging
capability improvement of the capsule endoscope.
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