Lateral flow immunoassay device with separation membrane

A lateral flow assay device for detecting an analyte of interest in a fluid sample comprising:

• a first flow path configured to receive the fluid sample, the first flow path extending between a top surface and a bottom surface of a membrane configured to retain particles in the fluid sample, the membrane comprising a plurality of edges between the top surface and the bottom surface;
• a second flow path extending from a buffer receiving zone through a sample receiving zone to a capture zone downstream of the sample receiving zone, the sample receiving zone comprising a conjugate comprising a label and an agent configured to specifically bind to the analyte of interest, the capture zone comprising an immobilized capture agent specific to the analyte of interest, the second flow path spatially below and in fluid communication with the bottom surface of the membrane, the buffer receiving zone configured to receive a buffer that directs the fluid sample received through the bottom surface of the membrane along the second flow path to the capture zone;
• and
• a cartridge defining a buffer well and a sample well in communication with the buffer receiving zone and the sample receiving zone, respectively, the cartridge comprising a plurality of compression structures comprising compression surfaces and compression posts, the compression surfaces comprising a bottom surface of the sample well in direct contact with the top surface of the membrane, the compression posts arranged upstream of the sample well and downstream of the sample well and above the top surface of the membrane, the compression surfaces and the compression posts configured to compress portions of the membrane and collectively generate a tension throughout the membrane that prevents leakage of the fluid sample out of the plurality of edges of the membrane and prevents the particles from flowing through the plurality of edges of the membrane to the second flow path.