[[File:Bio-layer interferometry without analyte binding.gif|thumb|Figure 1 - Overview schematic of a Bio-layer interferometry setup|300x300px]][[File:Thin film interference - soap bubble.gif|thumb|265x265px|Figure 2 - The ligand-analyte layer creates an optical path length difference, reflecting incident light in two different patterns]]'''Bio-layer interferometry''' ('''BLI''') is an optical biosensing technology that analyzes biomolecular interactions in real-time without the need for fluorescent labeling.<ref name="Apiyo_2017">{{Cite book| vauthors = Apiyo D, Schasfoort R, Schuck P, Marquart A, Gedig ET, Karlsson R, Abdiche YN, Eckman Y, Blum SR, Schasfoort RB |title=Handbook of Surface Plasmon Resonance.|date=2017|publisher=Royal Society of Chemistry|isbn=978-1-78801-139-6|oclc=988866146}}</ref> Alongside [[Surfacesurface plasmon resonance|Surface Plasmon Resonance]] (SPR), BLI is one of few widely available [[Label-free quantification|label-free]] biosensing technologies, a detection style that yields more information in less time than traditional processes.<ref>{{cite journal | vauthors = Syahir A, Usui K, Tomizaki KY, Kajikawa K, Mihara H | title = Label and Label-Free Detection Techniques for Protein Microarrays | journal = Microarrays | volume = 4 | issue = 2 | pages = 228–244 | date = April 2015 | pmid = 27600222 | pmc = 4996399 | doi = 10.3390/microarrays4020228 | doi-access = free }}</ref> The technology relies on the phase shift-wavelength correlation created between interference patterns off of two unique surfaces on the tip of a biosensor.<ref name=":1">{{cite journal | vauthors = Müller-Esparza H, Osorio-Valeriano M, Steube N, Thanbichler M, Randau L | title = Bio-Layer Interferometry Analysis of the Target Binding Activity of CRISPR-Cas Effector Complexes | journal = Frontiers in Molecular Biosciences | volume = 7 | pages = 98 | date = 2020-05-27 | pmid = 32528975 | pmc = 7266957 | doi = 10.3389/fmolb.2020.00098 | doi-access = free }}</ref> BLI has significant applications in quantifying binding strength, measuring protein interactions, and identifying properties of reaction kinetics, such as rate constants and reaction rates.<ref>{{cite journal | vauthors = Rich RL, Myszka DG | title = Higher-throughput, label-free, real-time molecular interaction analysis | journal = Analytical Biochemistry | volume = 361 | issue = 1 | pages = 1–6 | date = February 2007 | pmid = 17145039 | doi = 10.1016/j.ab.2006.10.040 }}</ref>
