Introduction

The invention was developed in the field of focusing and confinement of elastic waves. In particular, these phenomena are of interest for amplifying the performance of energy harvesters, i.e., devices that collect energy from the environment, in the form of kinetic energy related to vibrations, and transform it into electrical energy.

Technical features

The device (TRL 5) is based on a series of resonators of gradual length connected to an elastic waveguide. The application is not limited to the dimensions proposed in this exemplification. The system consists of a sequence of 9 cells, having a linear variation of resonator length. Each unit cell consists of two beams arranged symmetrically on either side of the waveguide. The physics of the device is based on the ‘rainbow effect’, which is the ability to separate the incoming signal in space as a function of frequency, as demonstrated in electromagnetism, acoustics, water waves, fluid-loaded plates, and deep elastic substrates, among others. The device demonstrates this property by leveraging a spatial distribution, along at the waveguide, of resonators with different frequency eigenfrequencies of the first flexural mode.

Possible Applications

• Microscale applications for energy confinement, energy localization, signal separation, signal slowing, sensing, vibration isolation.

Advantages

• Focusing and amplification of elastic waves by rainbow effect and subsequent performance amplification of energy harvesters, with a design fully compatible with micro-fabrication techniques;
• Similar patents are based on coupled piezoelectric resonator systems for energy harvesting or sensing, but without rainbow amplification.