Piezo-elements for wearable devices, including fitness trackers, smart watches and the like
Systems methods, and structures are provided that scavenge mechanical energy to provide electrical energy to a wearable, where the mechanical energy is scavenged by a bending-strain-based transducer that includes a non-resonant energy harvester. The bending-strain-based transducer also includes a sensor and/or a haptic device. The transducer may comprise a piezoelectric layer comprising a low-K piezoelectric material, such as aluminum nitride, which enables generation of higher voltage and power/energy output and/or a thinner transducer. Transducers in accordance with the present disclosure can be included in wearables for which large transducer thickness would be problematic, such as shoe insoles, midsoles or outsoles, garments, bras, handbags, backpacks, and the like.
1 . A wearable apparatus comprising:
(a) a transducer having a longitudinal axis that defines a first direction, wherein the transducer is a bending-strain-based transducer that includes:
(i) a first transducer element disposed on a first surface of a substrate, the first transducer element being a non-resonant energy harvester;
(ii) a second transducer element disposed on a second surface of the substrate, the first and second surfaces being on opposite sides of the substrate, wherein the second transducer element is selected from the group consisting of a resonant energy harvester, a non-resonant energy harvester, a force sensor, a load sensor, a pressure sensor, and a haptic device;
wherein the transducer is configured to bend in response to a first force that is at least partially directed along a second direction that is orthogonal to the first direction;
wherein the first transducer element is configured to provide a first output signal; and
wherein the second transducer element is configured to provide a second output signal or generate a first mechanical signal based on a first input signal;
(iii) a mechanically rigid structural support aligned with a second direction, the first transducer element having a third surface that is distal to the substrate and defines a first plane, and wherein the mechanically rigid structural support extends along the second direction to define a second plane, and further wherein the first plane is between the substrate and the second plane; wherein the mechanically rigid structural support functions as a fulcrum about which the transducer bends;
(b) a power handling circuit; and
(c) an energy storage module operatively coupled with the transducer and configured to store energy generated by the non-resonant energy harvesters, and provide power to the transducer and the other electronics included in the wearable apparatus.
2 . A wearable apparatus comprising:
(a) a transducer having a longitudinal axis that defines a first direction, wherein the transducer is a bending-strain-based transducer that includes:
(i) a first transducer element disposed on a first surface of a substrate, the first transducer element being a non-resonant energy harvester;
(ii) a second transducer element disposed on a second surface of the substrate, the first and second surfaces being on opposite sides of the substrate, wherein the second transducer element is selected from the group consisting of a resonant energy harvester, a non-resonant energy harvester, a force sensor, a load sensor, a pressure sensor, and a haptic device;
(iii) a mechanically rigid structural support aligned with a second direction, the first transducer element having a third surface that is distal to the substrate and defines a first plane, and wherein the mechanically rigid structural support extends along the second direction to define a second plane, and further wherein the first plane is between the substrate and the second plane; wherein the mechanically rigid structural support functions as a fulcrum about which the transducer bends;
wherein the transducer is configured to bend in response to a first force that is at least partially directed along a second direction that is orthogonal to the first direction;
wherein the first transducer element is configured to provide a first output signal; and
wherein the second transducer element is configured to provide a second output signal or generate a first mechanical signal based on a first input signal;
wherein the transducer is further configured to inhibit compression of at least one of the first and second transducer elements along the second direction in response to the first force;
(b) a power handling circuit; and
(c) an energy storage module operatively coupled with the transducer and configured to store energy generated by the non-resonant energy harvesters, and provide power to the transducer and the other electronics included in the wearable apparatus.
3 . A wearable apparatus comprising:
(a) a transducer having a longitudinal axis that defines a first direction, wherein the transducer is a bending-strain-based transducer that includes:
(i) a first transducer element disposed on a first surface of a substrate, the first transducer element being a non-resonant energy harvester;
(ii) a second transducer element disposed on a second surface of the substrate, the first and second surfaces being on opposite sides of the substrate, wherein the second transducer element is selected from the group consisting of a resonant energy harvester, a non-resonant energy harvester, a force sensor, a load sensor, a pressure sensor, and a haptic device;
(iii) a third transducer element disposed on the second surface, and wherein the third transducer element is a haptic device;
(iv) a mechanically rigid structural support aligned with a second direction, the first transducer element having a third surface that is distal to the substrate and defines a first plane, and wherein the mechanically rigid structural support extends along the second direction to define a second plane, and further wherein the first plane is between the substrate and the second plane; wherein the mechanically rigid structural support functions as a fulcrum about which the transducer bends;
wherein the transducer is configured to bend in response to a first force that is at least partially directed along a second direction that is orthogonal to the first direction;
wherein the first transducer element is configured to provide a first output signal; and
wherein the second transducer element is configured to provide a second output signal or generate a first mechanical signal based on a first input signal;
(b) a power handling circuit; and
(c) an energy storage module operatively coupled with the transducer and configured to store energy generated by the non-resonant energy harvesters, and provide power to the transducer and the other electronics included in the wearable apparatus.
4 . The wearable apparatus of claim 1 wherein the wearable is selected from the group consisting of a shoe insole, a shoe midsole, and an outsole.
5 . The wearable apparatus of claim 1 wherein the substrate comprises a material selected from the group consisting of a polyimide and a glass.
6 . The wearable apparatus of claim 1 wherein the substrate comprises a metal.
7 . The wearable apparatus of claim 1 wherein the first transducer element includes first and second electrodes and a piezoelectric layer that is between the first and second electrodes.
8 . The wearable apparatus of claim 7 wherein the piezoelectric layer comprises a low-K piezoelectric material.
9 . The wearable apparatus of claim 8 wherein the low-K piezoelectric material is selected from the group consisting of undoped aluminum nitride, doped aluminum nitride, scandium-doped aluminum nitride, undoped zinc oxide, doped zinc oxide, and polyvinylidene fluoride.
10 . The wearable apparatus of claim 7 wherein the piezoelectric layer comprises a thick high-K piezoelectric material.
11 . The wearable apparatus of claim 7 wherein the high-K piezoelectric material comprises thick lead-zirconate-titanate or doped lead-zirconate-titanate.
12 . The wearable apparatus of claim 1 wherein the transducer has a quiescent shape that is non-linear in a first plane that includes the second direction, and wherein transducer is configured to deform from its quiescent shape in the first plane in response to the first force.
13 . A wearable apparatus comprising a first bimorph transducer having a first longitudinal axis that defines a first direction, wherein the first bimorph transducer is a bending-strain-based transducer that includes:
(a) a first transducer element disposed on a first surface of a substrate, the first transducer element being a non-resonant energy harvester that provides a first output signal;
(b) a second transducer element disposed on a second surface of a substrate, the second transducer element being a sensor that provides a second output signal; and
(c) a third transducer element configured to provide a mechanical signal in response to a first input signa, wherein the third transducer element is a haptic device;
(d) a mechanically rigid structural support aligned with a second direction that is orthogonal to the first direction, the first transducer element having a surface that is distal to the substrate and defines a first plane, and wherein the mechanically rigid structural support extends along the second direction to define a second plane, and wherein the first plane is between the substrate and the second plane, wherein the mechanically rigid structural support functions as a fulcrum about which the transducer bends;
wherein the first bimorph transducer is further configured to inhibit compression of the first transducer element along the second direction in response to the first force
wherein the first bimorph transducer is configured to bend in response to a first force directed at least partially along the second;
wherein the wearable further includes a power handling circuit and an energy storage module operatively coupled with the first bimorph transducer and configured to store energy generated by the non-resonant energy harvesters, and provide power to the first bimorph transducer and the other electronics included in wearable.
14 . The wearable apparatus of claim 13 wherein the first transducer element includes a piezoelectric layer located between first and second electrical contacts.
15 . The wearable apparatus of claim 13 wherein the substrate comprises at least one material selected from the group consisting of a metal, a polyimide, and a glass.
16 . The wearable apparatus of claim 13 wherein the wearable includes:
a plurality of bimorph transducers that includes the first bimorph transducer;
a wireless communications module
wherein the plurality of bimorph transducers is operatively coupled with each of the power-handling circuit and the energy-storage module.
17 . The wearable apparatus of claim 16 wherein shoe insole defines a first plane and has a second longitudinal axis in the first plane, and wherein each bimorph transducers of the plurality thereof has a first lateral dimension along the first direction in the first plane and a second lateral dimension that is aligned with the second longitudinal axis, the second lateral dimension being smaller than the first lateral dimension.
18 . The wearable apparatus of claim 13 wherein the first bimorph transducer has a quiescent shape that is non-linear in a first plane that includes the second direction, and wherein the first bimorph transducer is configured to deform from its quiescent shape in the first plane in response to the first force.
19 . The wearable apparatus of claim 18 further comprising a plurality of bimorph transducers that includes the first bimorph transducer, wherein the plurality of bimorph transducers is linearly arranged along the second direction.
20 . The wearable apparatus of claim 13 further comprising an element selected from the group consisting of an accelerometer and an inertial sensor.
21 . The wearable apparatus of claim 13 further comprising a location module that is configured to provide an alert in response to a magnitude of a separation between the first bimorph transducer and a first location.
22 . The wearable apparatus of claim 1 wherein the transducer has a quiescent state in which the transducer has a thickness that is less than 1.3 millimeters.
23 . The wearable apparatus of claim 1 wherein the transducer has a quiescent state in which the transducer has a thickness that is less than 620 microns.
24 . The wearable apparatus of claim 1 wherein the transducer has a quiescent state in which the transducer has a thickness that is within the range of 100 microns to 210 microns.
25 . The wearable apparatus of claim 1 wherein at least one of the first transducer element and second transducer element includes a piezoelectric layer having a thickness that is less than or equal to 500 microns.
26 . The wearable apparatus of claim 4 wherein the wearable is configured to enable its reversible insertion into a footwear.
27 . The wearable apparatus of claim 26 wherein the footwear is selected from the group consisting of a shoe, a high-heel shoe, a sneaker, a cleat, and a slipper.
28 . The wearable apparatus of claim 4 wherein the wearable is non-reversibly integrated into a footwear.
29 . The wearable apparatus of claim 28 wherein the footwear is selected from the group consisting of a shoe, a high-heel shoe, a sneaker, a cleat, and a slipper.
30 . The wearable apparatus of claim 13 wherein the first bimorph transducer has a quiescent state in which the transducer is characterized by a thickness that is less than 1.3 millimeters.
31 . The wearable apparatus of claim 30 wherein the transducer has a quiescent state in which the transducer is characterized by a thickness that is within the range of 100 microns to 210 microns.