A lateral flow biosensor was developed based on newly established primer extension nucleic acid isothermal amplification (PEIA) and M13mp18 single-stranded DNA (ssDNA) to visually identify the H1N1 virus. The PEIA process was primer based on a template to continuously extend multiple repeat sequences, using DNA polymerase, to form long ssDNAs. M13mp18 ssDNA was then coupled to multiple long ssDNAs from PEIA and functionalized in a signal tag DNA nanostructure (STDN) for the lateral flow biosensor. In the presence of target H1N1-RNA, the sandwich structure capture probe/H1N1-RNA/STDN is fabricated caught in the lateral flow biosensor test zone, and appears red. Our biosensor successfully identified H1N1 virus RNA over a broad range of concentrations (10-106 pM) with a minimum visual detection limit of 10 pM. In conclusion, our biosensor may be applied to point-of-care diagnostics in low-resource environments with non-specialist staff.