Provided are a filter element and a method of preparing a filter element. The filter element includes a pattern substrate having a first channel formed on one surface and a second channel formed on the other surface and including a first base and a second base which have different liquid permeabilities; a first liquid metal pattern disposed in the first channel; a second liquid metal pattern disposed in the second channel and at least partially overlapping the first liquid metal pattern; and a contactor configured to invade in the first base and the second base and electrically connect the first liquid metal pattern to the second liquid metal pattern.