Magnetic inertial sensor energy harvesting and scavenging methods, circuits and systems
A magnetic energy harvesting and scavenging circuit includes a first substrate having a first surface and a second surface. An energy harvesting and scavenging coil is formed proximate the first surface. An electromechanical systems device, which may be a MEMS device, includes a moveable mass that extends over the first surface of the first substrate and may be displaced relative to the substrate in three dimensions responsive to an external force applied to the moveable mass. The movable mass includes at least one permanent magnet that is magnetically coupled to the energy harvesting and scavenging coil. Energy harvesting and scavenging circuitry, which may be formed in the first substrate where the first substrate is a semiconductor chip, is electrically coupled to the energy harvesting and scavenging coil and generates electrical energy due to magnetic flux variation through the energy harvesting and scavenging coil responsive to movement of the moveable mass.
1. A magnetic energy harvesting and scavenging circuit, comprising:
a first substrate having a first surface and a second surface;
at least one energy harvesting and scavenging coil formed proximate the first surface;
an electromechanical systems device including a moveable mass extending over the first surface of the first substrate and configured to be displaced relative to the first substrate in three dimensions responsive to an external force applied to the moveable mass, and the movable mass including at least one permanent magnet that is magnetically coupled to the at least one energy harvesting and scavenging coil; and
energy harvesting and scavenging circuitry electrically coupled to the at least one energy harvesting and scavenging coil, the energy harvesting and scavenging circuitry configured to generate electrical energy due to magnetic flux variation through the at least one energy harvesting and scavenging coil responsive to movement of the moveable mass.
2. The magnetic energy harvesting and scavenging circuit of claim 1 , wherein the energy harvesting and scavenging circuitry is formed in the first substrate.
3. The magnetic energy harvesting and scavenging circuit of claim 1 , wherein the energy harvesting and scavenging circuitry is formed external to the first substrate and is electrically coupled to the first substrate.
4. The magnetic energy harvesting and scavenging circuit of claim 1 further comprising a first semiconductor chip including the first substrate.
5. The magnetic energy harvesting and scavenging circuit of claim 4 , wherein the first semiconductor chip comprises a structural layer formed on the first substrate and wherein the at least one energy harvesting and scavenging coil is formed in the structural layer.
6. The magnetic energy harvesting and scavenging circuit of claim 1 , wherein the electrical energy generated by the energy harvesting and scavenging circuitry is generated responsive to an electrical quantity induced in the at least one energy harvesting and scavenging coil responsive to the magnetic flux variation.
7. The magnetic energy harvesting and scavenging circuit of claim 6 , wherein the electrical quantity is a voltage or a current.
8. A magnetic energy harvesting and scavenging circuit, comprising:
a first substrate having a first surface and a second surface;
at least one energy harvesting and scavenging coil formed proximate the first surface;
an electromechanical systems device including a moveable mass extending over the first surface of the first substrate and configured to be displaced relative to the first substrate in three dimensions responsive to an external force applied to the moveable mass, and the movable mass including a magnet support layer and a permanent magnet layer attached to the magnet support layer; and
energy harvesting and scavenging circuitry electrically coupled to the at least one energy harvesting and scavenging coil, the energy harvesting and scavenging circuitry configured to generate electrical energy due to magnetic flux variation through the at least one energy harvesting and scavenging coil.
9. The magnetic energy harvesting and scavenging circuit of claim 8 , wherein the magnet support layer comprises a plate having an upper surface and a lower surface facing the first surface of the first semiconductor chip, and wherein the permanent magnet layer is attached to the lower surface of the magnet support layer.
10. The magnetic energy harvesting and scavenging circuit of claim 1 , wherein the electromechanical systems device comprises a microelectromechanical systems (MEMS) device.
11. The magnetic energy harvesting and scavenging circuit of claim 10 wherein the MEMS device further comprises a packaging structure coupled to the first surface of the first semiconductor chip and defining an internal cavity that houses the moveable mass, the MEMS device further including a supporting structure coupled between the packaging structure and the moveable mass to moveably suspend the moveable mass within the internal cavity.
12. The magnetic energy harvesting and scavenging circuit of claim 11 wherein the supporting structure comprises a plurality of arms, each arm coupled between the packaging structure and the moveable mass.
13. The magnetic energy harvesting and scavenging circuit of claim 8 , wherein the energy harvesting and scavenging circuitry further comprises an AC/DC converter having an input coupled to the at least one energy harvesting and scavenging coil to receive a time varying voltage and time varying current from the at least one energy harvesting and scavenging coil.
14. The magnetic energy harvesting and scavenging circuit of claim 13 , wherein the first substrate is contained in a first chip and wherein the AC/DC converter includes an output coupled to a load that is either contained in the first chip or external to the first chip.