A power generator or sensor apparatus is provided. In another aspect, a power generator is used for water wave energy harvesting. A further aspect provides a power generator including a buoyant, waterproof and/or enclosed outer shell, at least one enclosed inner shell located within the outer shell, a first plurality of balls located between the outer and inner shells, a second plurality of balls located within the inner shell, and spaced apart electrodes affixed to an interior surface of the outer shell. Moreover, an aspect of the present power generator uses fluid, such as water wave movement and wind blowing, to cause nested shells to move which moves multiple balls therein between spaced apart electrodes to generate triboelectric charges or energy for a variety of applications.

The invention provides an energy generation and/or conversion system and method wherein an electrical power generator is controlled to periodically alternate between a contact-mode, during which elements of the generator are brought into contact to induce a state of charging, and a non-contact mode, during which plates of the generator are separated from one another and electrical energy is generated through electrostatic induction. Timing and duration of contact and non-contact modes are controlled by a controller, or by user commands, in dependence on a charge state of the elements of the generator: In this way elements are controlled to come into contact only when surface charge has fallen below a certain level, and re-charging is necessary; contact time between the elements may hence be minimisedthereby minimising incurred noise and surface wearwhilst still maintaining a given desired threshold power output.

The invention provides an energy generation and/or conversion system and method wherein an electrical power generator is controlled to periodically alternate between a contact-mode, during which elements of the generator are brought into contact to induce a state of charging, and a non-contact mode, during which plates of the generator are separated from one another and electrical energy is generated through electrostatic induction. Timing and duration of contact and non-contact modes are controlled by a controller, or by user commands, in dependence on a charge state of the elements of the generator: In this way elements are controlled to come into contact only when surface charge has fallen below a certain level, and re-charging is necessary; contact time between the elements may hence be minimisedthereby minimising incurred noise and surface wearwhilst still maintaining a given desired threshold power output.

An electret element includes: an Si layer, an SiO.sub.2 layer formed at a surface of the Si layer; and an electret formed at the SiO.sub.2 layer near an interface of the SiO.sub.2 layer and the Si layer.

An electret element includes: an Si layer, an SiO.sub.2 layer formed at a surface of the Si layer; and an electret formed at the SiO.sub.2 layer near an interface of the SiO.sub.2 layer and the Si layer.

A power generating element 1 according to an embodiment includes a displacement member 10, a displacement member 20, and a fixed member 30. The displacement member 10 and the displacement member 20 are connected via an elastic deformation body 41. The displacement member 10 is connected to an attachment section 51 via an elastic deformation body 42. The displacement member 10 and/or the displacement member 20 includes a first power generation surface. The fixed member 30 includes a second power generation surface opposed to the first power generation surface. An electret material layer is provided on one surface of the first power generation surface and the second power generation surface. A counter electrode layer is provided on the other surface.

A power generating element 1 according to an embodiment includes a displacement member 10, a displacement member 20, and a fixed member 30. The displacement member 10 and the displacement member 20 are connected via an elastic deformation body 41. The displacement member 10 is connected to an attachment section 51 via an elastic deformation body 42. The displacement member 10 and/or the displacement member 20 includes a first power generation surface. The fixed member 30 includes a second power generation surface opposed to the first power generation surface. An electret material layer is provided on one surface of the first power generation surface and the second power generation surface. A counter electrode layer is provided on the other surface.

Provided is an electrostatic energy harvester Including a lower electrode; a ferroelectric material layer which is disposed on the lower electrode and formed of a poled ferroelectric material; a friction-charged body which is adapted to be repeatedly contacted with and separated from the ferroelectric material layer and has an electric susceptibility different from an electric susceptibility of the ferroelectric material layer; and an upper electrode provided on the friction-charged body.

Provided is an electrostatic energy harvester Including a lower electrode; a ferroelectric material layer which is disposed on the lower electrode and formed of a poled ferroelectric material; a friction-charged body which is adapted to be repeatedly contacted with and separated from the ferroelectric material layer and has an electric susceptibility different from an electric susceptibility of the ferroelectric material layer; and an upper electrode provided on the friction-charged body.

The present disclosure enables materials of a triboelectric charging member to exhibit a characteristic of increased surface charge density, thereby improving output of a triboelectric generating device. Accordingly, the present disclosure provides a triboelectric generating device showing improved output without increasing a size of the triboelectric generating device or without increasing amounts of materials required for the triboelectric generating device. An embodiment of a triboelectric generating device provided according to a first aspect of the present disclosure includes a first electrode; a first charging layer formed on the first electrode; and a second electrode disposed on the first charging layer, wherein the first charging layer and the second electrode are arranged such that an interface between the first charging layer and the second electrode forms a frictional interface, and the first charging layer includes a ferroelectric polymer matrix and ferroelectric inorganic particles dispersed in the ferroelectric polymer matrix.