Therealizationofanefficientopticalsensorbasedonaphotoniccrystalmetasurfacesupportingboundstatesinthecontinuumisreported.Liquidswithdifferentrefractiveindices,rangingfrom1.4000to1.4480,areinfiltratedinamicrofluidicchamberbondedtothesensingdielectricmetasurface.Abulkliquidsensitivityof178nm/RIUisachieved,whileaQ-factorofabout2000givesasensorfigureofmeritupto445inairatbothvisibleandinfraredexcitations.Furthermore,thedetectionofultralow-molecular-weight（186Da）moleculesisdemon-stratedwitharecordresonanceshiftof6nmperlessthanaInmthicksinglemolecularlayer.Thesystemexploitsanormal-to-the-surfaceopticallaunchingscheme,withexcellentinterrogationstabilityanddemonstratesalignment-freeperformances,overcomingthelimitsofstandardphotoniccrystalsandplasmonicresonantconfigurations.
