Device for a membrane assay

A device for a membrane assay using a lateral flow immunoassay method comprising:

• a sample supply part which supplies a sample containing a subject to be detected;
• a labeling component part containing a labeling component which labels a subject to be detected in the sample from the sample supply part;
• a development part formed with a detection part which includes a trapping reagent for detecting or quantifying the labeled subject to be detected from the sample;
• and
• an absorption part which receives the sample from the detection part;
• wherein
• a non-woven fabric comprises fibers as the labeling component part,
• the labeling component part of said non-woven fabric consists of a split fiber type composite fiber having a structure arranged with a plurality of second fiber components consisting of polyester resin with a fiber diameter from 0.05 μm to 10 μm on a cross sectional exterior periphery of a first fiber component consisting of a polyolefin resin with a fiber diameter from 6 μm to 20 μm, and
• the first fiber component and the plurality of second fiber components are interlaced.