Piezoelectric actuator and microfluidic device
A piezoelectric actuator includes a deflectable membrane and a piezoelectric element attached to a part of the deflectable membrane for exerting a mechanical force on the deflectable membrane. The piezoelectric element is operable to perform an expansion and a contraction motion depending on an electric field applied to the piezoelectric element. The piezoelectric element leaves open a central region of the deflectable membrane and has a peripheral outline that does not coincide with an outline of the deflectable membrane.
1 . A piezoelectric actuator, comprising:
a deflectable membrane; and
at least one piezoelectric element attached to a part of the deflectable membrane for exerting a mechanical force on the deflectable membrane, the piezoelectric element is operable to perform an expansion and a contraction motion depending on an electric field applied to the piezoelectric element, the piezoelectric element has a peripheral outline that does not coincide with an outline of the deflectable membrane, and
wherein the piezoelectric actuator comprises an elastic support device for supporting the piezoelectric actuator.
2 . The piezoelectric actuator of claim 1 , wherein the piezoelectric element is a ring-shaped planar plate attached to the deflectable membrane.
3 . The piezoelectric actuator of claim 2 , wherein a ring-shaped inner region of the piezoelectric element covers a ring-shaped peripheral region of the deflectable membrane.
4 . The piezoelectric actuator of claim 1 , wherein the piezoelectric element includes a first ring-shaped planar plate and a second ring-shaped planar plate.
5 . The piezoelectric actuator of claim 4 , wherein the first ring-shaped planar plate and the second ring-shaped planar plate have outer and/or inner diameters that differ from one another.
6 . The piezoelectric actuator of claim 4 , wherein the first ring-shaped planar plate and the second ring-shaped planar plate are attached to a pair of opposing peripheral surfaces of the deflectable membrane.
7 . The piezoelectric actuator of claim 4 , wherein the first ring-shaped planar plate and the second ring-shaped planar plate have differing thicknesses.
8 . The piezoelectric actuator of claim 4 , wherein a void between the first ring-shaped planar plate and the second ring-shaped planar plate is at least partially filled with a spacer material.
9 . The piezoelectric actuator of claim 2 , wherein the ring-shaped planar plate has an outer diameter that is larger than an outer diameter of the deflectable membrane.
10 . The piezoelectric actuator of claim 2 , wherein the ring-shaped planar plate abuts an outer circumferential end face of the deflectable membrane.
11 . The piezoelectric actuator of claim 10 , wherein the piezoelectric element is attached to only a part of the outer circumferential end face of the deflectable membrane.
12 . The piezoelectric actuator of claim 1 , wherein a thickness of the deflectable membrane varies along a radial direction of the deflectable membrane.
13 . The piezoelectric actuator of claim 1 , wherein the deflectable membrane has a plurality of regions fabricated from different materials.
14 . The piezoelectric actuator of claim 1 , further comprising a bending piezoelectric element attached to the deflectable membrane in a central region of the deflectable membrane, the bending piezoelectric element applies a bending moment on the deflectable membrane.
15 . The piezoelectric actuator of claim 1 , wherein the deflectable membrane has a plurality of regions with material modifications.
16 . The piezoelectric actuator of claim 15 , wherein the deflectable membrane has a pre-defined deflected shape without the piezoelectric element exerting the mechanical force on the deflectable membrane.
17 . A microfluidic device, comprising:
a piezoelectric actuator including a deflectable membrane and at least one piezoelectric element attached to a part of the deflectable membrane for exerting a mechanical force on the deflectable membrane, the piezoelectric element is operable to perform an expansion and a contraction motion depending on an electric field applied to the piezoelectric element, the piezoelectric element has a peripheral outline that does not coincide with an outline of the deflectable membrane, and
wherein the piezoelectric actuator comprises an elastic support device for supporting the piezoelectric actuator.
18 . The microfluidic device of claim 17 , further comprising a pair of fluid ports and a valve seat arranged around one of the pair of fluid ports and protruding from the one of the fluid ports toward the deflectable membrane.
19 . The microfluidic device of claim 18 , wherein the deflectable membrane is operable to close and open a fluidic pathway by contacting and moving away from the valve seat.
20 . The microfluidic device of claim 17 , further comprising a pair of fluid ports, the piezoelectric actuator is operable to expel a fluid out of at least one of the pair of fluid ports.
21 . The microfluidic device of claim 17 , wherein, by controlling a deflection of the deflectable membrane, a proportional valve is formed which controls a flowrate and/or pressure of a fluid.
22 . The piezoelectric actuator of claim 1 , wherein the deflectable membrane is deflectable in two opposing directions.
23 . The piezoelectric actuator of claim 1 , wherein the piezoelectric element comprises at least one ring-shaped planar plate which is attached to the deflectable membrane and has an outer diameter that is smaller than an outer diameter of the deflectable membrane, wherein an extension of the deflectable membrane beyond the piezoelectric elements' dimensions is usable for mounting the piezoelectric actuator.
24 . The piezoelectric actuator of claim 1 , further comprising one or more bending piezoelectric elements attached to one or both opposing surfaces of different locations of the deflectable membrane.
25 . The piezoelectric actuator of claim 24 , wherein both a central region and a peripheral region of one or both opposing surfaces of the deflectable membrane comprise piezoelectric elements and/or bending piezoelectric elements.
26 . A piezoelectric actuator, comprising:
a deflectable membrane being deflectable in two opposing directions; and
at least a first piezoelectric element and at least a second piezoelectric element, attached to opposing surfaces of the deflectable membrane for exerting a mechanical force on the deflectable membrane, the piezoelectric elements being operable to perform an expansion and/or a contraction motion depending on electric fields applied to the piezoelectric elements,
wherein an outer outline diameter of the first and/or the second piezoelectric elements, in at least a portion, is larger than an outer outline diameter of the deflectable membrane.
27 . The piezoelectric actuator of claim 26 , wherein the piezoelectric actuator comprises an elastic support device for supporting the piezoelectric actuator, the elastic support device being provided at the piezoelectric element or at a spacer arranged around the deflectable membrane.
28 . The piezoelectric actuator of claim 26 , wherein a flexible spacer material at least partly fills a void between the first and second piezoelectric elements.
29 . The piezoelectric actuator of claim 28 , wherein the flexible spacer material comprises a ring-shaped structure cut from the same material as the deflectable membrane, with one or more radially extending webs connecting it to the deflectable membrane.
30 . A microfluidic device, comprising:
a piezoelectric actuator including a deflectable membrane being deflectable in two opposing directions; and
at least a first piezoelectric element and at least a second piezoelectric element, attached to opposing surfaces of the deflectable membrane for exerting a mechanical force on the deflectable membrane, the piezoelectric elements being operable to perform an expansion and/or a contraction motion depending on electric fields applied to the piezoelectric elements,
wherein an outer outline diameter of the first and/or the second piezoelectric elements, in at least a portion, is larger than an outer outline diameter of the deflectable membrane.
31 . The piezoelectric actuator of claim 1 , further comprising a flexible spacer material having a ring-shaped structure cut from the same material as the deflectable membrane, with one or more radially extending webs connecting it to the deflectable membrane.
32 . The piezoelectric actuator of claim 26 , wherein the first piezoelectric element is a first ring-shaped planar plate and the second piezoelectric element is a second ring-shaped planar plate.
33 . The piezoelectric actuator of claim 32 , wherein the first ring-shaped planar plate and the second ring-shaped planar plate have outer and/or inner diameters that differ from one another.
34 . The piezoelectric actuator of claim 32 , wherein the first ring-shaped planar plate and the second ring-shaped planar plate have differing thicknesses.
35 . The piezoelectric actuator of claim 26 , wherein a thickness of the deflectable membrane varies along a radial direction of the deflectable membrane.
36 . The piezoelectric actuator of claim 26 , wherein the deflectable membrane has a plurality of regions fabricated from different materials.
37 . The piezoelectric actuator of claim 26 , wherein the deflectable membrane has a plurality of regions with material modifications.
38 . The piezoelectric actuator of claim 37 , wherein the deflectable membrane has a pre-defined deflected shape without the first piezoelectric element and the second piezoelectric element exerting the mechanical force on the deflectable membrane.
39 . The piezoelectric actuator of claim 26 , wherein the deflectable membrane is deflectable in two opposing directions.
40 . The piezoelectric actuator of claim 26 , further comprising one or more bending piezoelectric elements attached to one or both opposing surfaces of different locations of the deflectable membrane.
41 . The piezoelectric actuator of claim 40 , wherein both a central region and a peripheral region of one or both opposing surfaces of the deflectable membrane comprise piezoelectric elements and/or bending piezoelectric elements.
42 . The microfluidic device of claim 30 , further comprising a pair of fluid ports and a valve seat arranged around one of the pair of fluid ports and protruding from the one of the fluid ports toward the deflectable membrane.
43 . The microfluidic device of claim 42 , wherein the deflectable membrane is operable to close and open a fluidic pathway by contacting and moving away from the valve seat.
44 . The microfluidic device of claim 30 , further comprising a pair of fluid ports, the piezoelectric actuator is operable to expel a fluid out of at least one of the pair of fluid ports.
45 . The microfluidic device of claim 30 , wherein, by controlling a deflection of the deflectable membrane, a proportional valve is formed which controls a flowrate and/or pressure of a fluid.