Energy scavengers which adjust their frequency by altering liquid distributions on a beam

A beam having a selectively alterable mass distribution, the beam comprising:

• a beam body defining a first end, a second end generally opposite from the first end, and a hollow region extending at least partially between the first end and the second end;
• an effective amount of a liquid disposed in the hollow region;
• an effective amount of a gas also disposed in the hollow region;
• and
• a heating array adapted to selectively heat a localized area of the hollow region, the heating array disposed across at least a portion of the hollow region and in thermal communication with the liquid and the gas disposed therein;
• whereby upon actuation of the heating array, the localized area of the hollow region is heated, thereby displacing the liquid and gas disposed within the hollow region and thus altering the mass distribution of the beam.

A beam having a selectively alterable mass distribution, the beam comprising:

• a longitudinal beam body defining a first end, a second end, a first reservoir proximate the first end, a second reservoir proximate the second end, and a channel extending between the first reservoir and the second reservoir, the channel providing flow communication between the first reservoir and the second reservoir;
• a first heating element disposed proximate the first reservoir;
• a second heating element disposed proximate the second reservoir;
• an effective amount of liquid disposed in at least one of the first reservoir, the second reservoir, and the channel;
• and
• an effective amount of a gas disposed in at least one of the first reservoir, the second reservoir, and the channel;
• whereby upon actuation of one of the first heating element and the second heating element, the gas locates proximate the actuated heating element, thereby altering the mass distribution of the beam.

A method for optimizing energy harvest from a vibrating surface, the method comprising:

• providing a beam having a selectively alterable mass distribution, the beam defining an enclosed hollow region and comprising an effective amount of a liquid selectively displaceable within the hollow region upon application of either an electrical potential or thermal energy;
• identifying the frequency of vibration of the vibrating surface;
• and
• altering the mass distribution of the beam by application of either the electrical potential or thermal energy such that the natural frequency of the beam matches or substantially so, the frequency of vibration of the vibrating surface.