Abstract: The invention provides a probe for detecting a target polynucleotide. The probe contains a region that base-pairs with a target polynucleotide to form a duplex and a RNA hairpin extension domain that increases the stability of the duplex. The probe may further include a nucleotide clamp, a stem-complementary region and/or a linker moiety. Also provided is an array of subject probes bound to a surface of a solid support. Methods of using a subject probe to assess target polynucleotides, e.g., small RNAs, in a sample are provided, as are kits for use in practicing the subject methods.