Fig. 1: Supramolecular dipoles in low-dielectric organic crystals produce significant piezoelectric properties that can be exploited for energy harvesting.
From: Organic piezoelectric materials: milestones and potential

a Glycine intermolecular dipoles when the amino acid is crystallized in a monoclinic space group. b Open circuit voltages generated by biological energy harvesters in the past decade10,26,39,40,41,42,43,44. c Comparison of the piezoelectric strain constants of a variety of biomaterials versus their inorganic counterparts. For exact values and citations see Supplementary Table 1