Embodiments disclosed herein include devices, methods, and systems for direct, selective, and sensitive detection of single-stranded target RNA sequences from various sources using a programed Cas13a protein. When activated by binding a target RNA sequence, the Cas13a cleaves a tether releasing a reporter molecule that may then be detected. In some embodiments, the systems, methods, and devices may include a filter or membrane that may help to separate the tethered and untethered reporter molecules. These devices, systems, and techniques allow a user to rapidly process samples that may contain the target RNA, without needing to amplify the target sequences. These devices and methods may be used to assay a wide variety of samples and target RNA sources, for the presence or absence of a specific target RNA sequence. Compositions and kits, useful in practicing these methods, for example detecting a target RNA in a biological sample, are also described.