Patent ID: 8906234

Claim:
A filter device comprising: a capillary; and a filter chip provided inside the capillary such that is brought into contact with a solution containing a substance and flowing in the capillary, wherein the filter chip includes: a thin plate; and a through hole which penetrates a first surface at an upper part of the thin plate and a second surface provided opposite to the first surface, and through which the solution flowing in the capillary passes from the first surface to the second surface, wherein a filter portion made of a plurality of fibrous substances including inorganic oxide is formed at a portion above the through hole so as to cover an opening portion of the through hole opened in the first surface, and the plurality of fibrous substances have one peak in diameter distribution, wherein the plurality of fibrous substances are entangled with each other, and wherein the filter portion includes gaps made by the entangled plurality of fibrous substances, and the gaps become narrower toward a downstream of the capillary.