The conformational dynamics of RNA are crucial to its role in numerous essential biological functions. Even simple RNA structures such as stem-loops undergo rearrangements within an intricate three-dimensional network of secondary and tertiary interactions, resulting in motions that span a broad range of timescales. This complexity gives rise to a large number of experimental techniques sampling different aspects of the folding and unfolding process. In order to address the divergence and limitations of these methods, we used carbon nanotube (CNT)-based single-molecule field-effect transistors (smFET) as a platform for studying the folding and unfolding dynamics of RNA. By taking advantage of the highly sensitive electronic properties and nanoscale dimensions of CNTs, and by optimizing the tethering of a single charged biomolecule, it is possible to directly monitor the fluctuations and characterize the kinetics associated with these motions. In this manner, we studied the conformational dynamics of individual RNA stem-loops and observed kinetic heterogeneities supporting previous evidence of the complex free-energy landscape of RNA folding and unfolding. With this improved smFET methodology, this technique can be applied to many other essential and increasingly complex RNA interactions to achieve a fuller understanding of crucial biological processes.