A piezoelectric transducer is provided herein, comprising a three-dimensional structure made of a plurality of peptides, the peptides being self-assembling and the structure being piezoelectric, wherein at least a portion, or each, of said plurality of peptides comprises peptides of 2 to 10 amino acid residues, provided that the plurality of peptides is not consisted of a plurality of Phe-Phe dipeptides. Further described herein are peptides having an amino acid sequence Hyp-Phe-Phe, Boc-Dip-Dip, (L)Trp-(D)Trp or (D)Trp-(L)Trp, as well as three-dimensional structures comprising such peptides.