Just to add to the conversation of determining Significant vs Non significant risk medical device studies, the FDA has a guidance document.
https://www.fda.gov/downloads/RegulatoryInformation/Guidances/UCM126418.pdf

The guidance document is intended to provide information and advice to sponsors, clinical investigators, and IRBs on how to determine the differences between significant risk and nonsignificant risk medical device studies. It supersedes the Significant Risk and Nonsignificant Risk Medical Device Studies(1998). This document was updated to include a list of examples of significant and nonsignificant risk devices, to clarify the IRB’s responsibilities when making the risk determination for investigational medical devices, and to make the guidance consistent with the Agency’s good guidance practices regulations (21 CFR 10.115).