A　biosensor　based　on　single-fiber　optical　tweezers　is　proposed,　which　can　detect　the　motion　trajectory　of　cells　based　on　the　stable　capture　and　transmission　of　silica　microspheres　as　well　as　biological　yeast　cells　by　using　a　tapered　optical　fiber　as　a　sensing　element.　The　interference　cavity　is　formed　by　using　the　fiber　tip　and　the　target　particle,　the　detected　interference　signal　is　demodulated　using　Hilbert　transform,　and　the　displacement　curve　of　the　particle　is　plotted　to　realize　the　particle　motion　trajectory　tracking.　This　method　provides　potential　technical　support　for　process　monitoring　of　targeted　drug　delivery　in　biomedicine.　©　2023,　Tianjin　University　of　Technology.