Electrostatic device, electrostatic device intermediate body and production method

An electrostatic device comprising:

• a fixed portion, a moveable portion, and an elastically-supporting portion that are formed in a substrate, the elastically-supporting portion elastically supporting the moveable portion;
• a first glass package having a first peripheral portion that is anodically bonded to a peripheral portion of a first surface of the substrate that includes the fixed portion;
• and
• a second glass package having a second peripheral portion that is anodically bonded to a second surface of the peripheral portion of the substrate that includes the fixed portion, wherein the first and second surfaces are opposite sides of the substrate, wherein the first glass package and the second glass package form a sealed space and the moveable portion is arranged in the sealed space between the first and second glass packages, wherein
• the elastically-supporting portion comprises a fixed area that is included in the peripheral portion of the substrate that is bonded to the first glass package and to the second glass package,
• the fixed portion and the fixed area are separated by a groove formed in the peripheral portion of the substrate,
• at least a part of one of the fixed portion and the moveable portion includes an electret, and
• a first electrode connected to the fixed portion and exposed on an outer surface of the second glass package and a second electrode connected to the elastically-supporting portion and exposed on the outer surface of the second glass package are formed in the second glass package.