From its inception, one of the major aims of the field of synthetic biology was to reliably manipulate microorganisms to create novel solutions in medicine and biotechnology. This is possible due to the remarkable diversity of natural interactions they carry out to regulate gene expression. Bacterial cells for instance contain sophisticated regulatory networks that modulate expression based on environmental cues. This sense and response mechanism could have tremendous utility in resource-limited environments. In such places, lack of access to affordable, rapid diagnostic tools means that viral and bacterial contamination of public water sources present a serious threat to public health. Before applications can be addressed, cellular circuits must be synthetically repurposed. Traditionally, engineers have relied upon protein-based regulatory networks. In recent times however, the mechanistic flexibility of RNA has emerged. It is now recognized as a powerful tool for rewiring biological circuits. In the present paper, combining a toehold-based design with STAR transcriptional activators resulted in the development of a flexible RNA-based sensing device. A colorimetric LacZ assay, in vivo fluorescence assay and a suite of molecular biology techniques demonstrated the sensing capability of the modified RNAs with a fold activation of 1.5. This work provides direction for the development of high-performance flexible RNA sensors. The paper concludes with recommendations for future work in this area including RNA structural approaches and an exploration of in vitro, paper based circuitry.