Patent ID: 8111847

Claim:
A speaker comprising: at least one electrode electrically coupled with an audio signal input; a film comprising at least one electret layer, the film being configured to interact with the electrode in response to an audio signal supplied by the audio signal input and to vibrate to generate sound waves, wherein the electret layer is formed from a polymer-containing solution which includes a polymer with a surfactant mixed therein, wherein the polymer comprises at least one of cyclic olefin copolymer (COC), polystyrene (PS), polycarbonate (PC), polymethylmethacrylate (PMMA), polyvinyl chloride (PVC), polyimide (PI), polyetherimide (PEI), high density polyethylene (HDPE), polypropylene (PP), and wherein the surfactant comprises at least one of (n+1)-hydroxy-alkanoic acid, (n+1)-amino-alkanoic acid, HO—(CH 2 )n-COOH, 2,3-bis-(n-hydroxy-alkyloxy)-succinic acid, 2,3-bis-(n-amino-alkyloxy)-succinic acid, (n+1)-triazol-alkanoic acid, and 2,3-bis-(n-triazol-alkyloxy)-succinic acid.