Modified energy harvesting figures of merit for stress- and strain-driven piezoelectric systemsJames I. Roscow, Holly Pearce, Hamideh Khanbareh, Sohini Kar-Narayan and Chris R. BowenEur. Phys. J. Special Topics, 228 7 (2019) 1537-1554DOI: https://doi.org/10.1140/epjst/e2019-800143-7