Topologically Enhanced Infrared Sensing Through Aluminum Scandium Nitride Radiofrequency Piezoelectric Metamaterials

NEMS/MEMS sensors struggle to simultaneously achieve high responsivity and high accuracy when sensing highly localized parameters. To overcome this limitation, we present a new MEMS piezoelectric sensor able to achieve accurate localized sensing by exploiting the exotic properties of a topological interface state (IS) excited at the shared boundary of two elastic piezoelectric periodic structures. This device, consisting of the first RF MEMS thin-film topological sensor ever reported, uses a suspended thin-film Aluminum Scandium Nitride piezoelectric layer. We have validated the use of the reported MEMS device by using it for infrared sensing. We demonstrate that the IS's strong mode localization enables a >4 times higher responsivity to infrared power compared to the responsivity achieved by a trivial (i.e., not localized) bulk mode that the same device transduces at a slightly different frequency.