MEMS SYSTEM
20210380402 · 2021-12-09
Inventors
Cpc classification
B81B2201/0257
PERFORMING OPERATIONS; TRANSPORTING
B81B5/00
PERFORMING OPERATIONS; TRANSPORTING
G02B26/085
PHYSICS
B81B2201/042
PERFORMING OPERATIONS; TRANSPORTING
H01F41/30
ELECTRICITY
International classification
B81B5/00
PERFORMING OPERATIONS; TRANSPORTING
H01F41/30
ELECTRICITY
Abstract
A MEMS system includes a first permanent-magnetic microstructure and a second permanent-magnetic microstructure. The first permanent-magnetic microstructure is movable along a first direction. The second permanent-magnetic microstructure is arranged to be spaced apart from the first permanent-magnetic microstructure, wherein, by moving the first permanent-magnetic microstructure along the first direction, the second permanent-magnetic microstructure or one or more elements of the second permanent-magnetic microstructure are either moved or actuated in a second direction or undergo rotation.
Claims
1. A MEMS system, comprising: a first permanent-magnetic microstructure movable along a first direction; a second permanent-magnetic microstructure arranged to be spaced apart from the first permanent-magnetic microstructure, wherein, by moving the first permanent-magnetic microstructure along the first direction, the second permanent-magnetic microstructure or one or more elements of the second permanent-magnetic microstructure are either moved or actuated in a second direction or undergo rotation; wherein the first permanent-magnetic microstructure is formed by a first array comprising a plurality of permanent-magnetic elements; or wherein the second permanent-magnetic microstructure is formed by a second array comprising a plurality of the permanent-magnetic elements; and wherein the plurality of the permanent-magnetic elements of the first or second array are rigidly connected to one another so that they are similarly moved or actuated as a result of a movement of the first permanent-magnetic microstructure along the second direction.
2. The MEMS system according to claim 1, wherein the first permanent-magnetic microstructure is formed by an array; and wherein the second permanent-magnetic microstructure is formed by an array.
3. The MEMS system according to claim 2, wherein each element of the first or the second array comprises an edge length in the range of 10 μm to 2 mm, advantageously in the range of 20 μm to 1000 μm, particularly advantageously in the range of 30 μm to 800 μm; and/or wherein the respective array comprises a repeat spacing of the elements in the range of 10 μm to 4 mm, advantageously in the range of 20 μm to 1500 μm, particularly advantageously in the range of 50 μm 1000 μm.
4. The MEMS system according to claim 1, wherein the first and second permanent-magnetic microstructures are configured such that, over an entire range of motion of the first and second permanent-magnetic structures, a spacing is in a range of 1 μm to 5 mm or in a range of 5 μm to 2000 μm or in a range of 10 μm to 1000 μm.
5. The MEMS system according to claim 1, wherein the first permanent-magnetic microstructure is magnetized in parallel with or is magnetized in opposite direction to the second permanent-magnetic microstructure.
6. The MEMS system according to claim 1, wherein the second direction is different from the first direction; or wherein the second direction is perpendicular to the first direction.
7. The MEMS system according to claim 1, wherein the second permanent-magnetic microstructure or the one or more elements of the second permanent-magnetic microstructure forming the second array are each rotated about an axis of rotation that is perpendicular to the first direction.
8. The MEMS system according to claim 1, wherein the MEMS system comprises a support for the first permanent-magnetic structure that restricts movement or actuation perpendicular to the first direction.
9. The MEMS system according to claim 1, wherein the second permanent-magnetic microstructure or the one or more elements of the second permanent-magnetic microstructure are supported by means of a support which restricts movement or actuation perpendicular to the second direction or which only permits rotation about a rotation point or points defined by the second permanent-magnetic microstructure.
10. The MEMS system according to claim 1, wherein the first permanent-magnetic microstructure or one or more elements of the first permanent-magnetic microstructure and/or the second permanent-magnetic microstructure or the one or more elements of the second permanent-magnetic microstructure extend along a third direction which is perpendicular to the first and second directions.
11. The MEMS system according to claim 1, wherein the plurality of permanent-magnetic elements are individually supported such that they are similarly moved or actuated or undergo a similar rotation as a result of a movement of the first permanent-magnetic microstructure along the second direction.
12. The MEMS system according to claim 1, wherein the plurality of permanent-magnetic elements are individually supported such that the plurality of permanent-magnetic elements undergo individual movement or actuation in response to the movement of the first permanent-magnetic structure.
13. The MEMS system according to claim 1, wherein the first permanent-magnetic structure comprises a singular number or a plurality of permanent-magnetic elements facing the plurality of permanent-magnetic elements of the second permanent-magnetic structure; or wherein the first permanent-magnetic structure comprises a plurality of permanent-magnetic elements facing the same plurality of permanent-magnetic elements of the second permanent-magnetic microstructure.
14. The MEMS system according to claim 1, further comprising a micromechanical actuator connected or coupled to the first permanent-magnetic structure, wherein the micromechanical actuator is configured to move the first permanent-magnetic structure along the first direction.
15. The MEMS system according to claim 1, wherein the first permanent-magnetic microstructure and the second permanent-magnetic microstructure are formed within a substrate.
16. The MEMS system according to claim 15, wherein the first direction extends laterally along the substrate; and wherein the second direction extends laterally along the substrate or perpendicular to the substrate.
17. The MEMS system according to claim 1, wherein the first or second permanent-magnetic microstructure is arranged in a chamber such that the first permanent-magnetic microstructure is encapsulated with respect to the second permanent-magnetic microstructure.
18. A method of manufacturing a MEMS system according to claim 1, comprising: agglomeration of powder by means of atomic layer deposition or by means of deposition to form the first and/or the second permanent-magnetic microstructure or to form the one or more elements of the first and/or the second permanent-magnetic microstructure.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Embodiments of the present invention will be explained with reference to the accompanying drawings, in which:
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[0033]
DETAILED DESCRIPTION OF THE INVENTION
[0034] Before explaining embodiments of the present invention with reference to the accompanying drawings, it should be noted that elements and structures of equal effect are provided with same reference signs so that the description thereof is mutually applicable or interchangeable.
[0035] As explained above, embodiments are based on micromechanical structures or elements of micromechanical structures being magnetically coupled to one another so that they can transmit forces from one micromechanical structure to another micromechanical structure and/or they influence one another in their movement. Since such embodiments are based on the fact that micromechanical structures are implemented to be permanent-magnetic, a brief overview of the contactless magnetic force transfer elements already in use is given below. In MEMS systems, mainly hybrid-mounted or external permanent magnets in combination with coils have been used for direct force generation [19, 20]. Such components are shown in
[0036]
[0037] Since the magnetic force effect scales with the volume, the largest possible magnets are advantageous. Structures with edge lengths of a few ten to a few hundred micrometers would be ideal for MEMS. However, typical deposition processes in semiconductor technology are implemented for layers with a thickness of a few micrometers, so that the volume of magnets produced in this way remains very small. Classical sintering processes are only suitable for producing much larger structures. Recently, more work has therefore been done on manufacturing processes for micromagnets “with volume”. The deposition of thick NdFeB layers by sputtering or pulsed laser deposition (PLD) [21] should be mentioned. One problem is patterning such layers. In [22], this is solved by sputtering microcolumns with NdFeB and their subsequent transfer into a flexible polymer membrane, see
[0038]
[0039] An attractive alternative to the previously mentioned methods is based on the agglomeration of loose powder by means of Atomic Layer Deposition (ALD) [25]. In this way, permanent-magnetic microstructures with edge lengths between 50 μm and 2000 μm could be generated on planar substrates for the first time in a reproducible manner and compatible with MEMS manufacturing processes. In [26], a piezoelectric vibrating harvester with a micromagnet array at the free-moving end of a bending beam is described. The device is actuated not only by vibrations or shocks, but also by variable magnetic fields caused, for example, by a moving external permanent magnet. Thanks to this, it is possible for the first time to generate energy from rotary motion with a MEMS device. An implementation based on conventional magnets and piezo actuators is disclosed in [27].
[0040] Based on this situation, an improvement can be created by the concept shown in
[0041] Both elements 10 and 15 are movable, the movability of element 10 being restricted such that it is movable substantially along the vector 10v (parallel to x), while movement in the y and/or z direction is restricted. The element 15 is movable along the vector 15v extending in the y direction, thus restricting movement in the z and/or x direction. According to embodiments, this restriction is performed by a support. In the following, the mode of operation of the permanent-magnetic structures 10 and 15 shown here will be explained. The use of permanent-magnetic microstructures 10 and 15 in MEMS enables the contactless transmission of forces, e.g. in the range of 1 μN to 1 mN. It is exemplarily assumed that the permanent-magnetic microstructure 10 is moved along the direction 10v, e.g. by an actuator integrated in the MEMS device. Due to magnetism, the permanent-magnetic microstructure 15 is then excited to move. This extends along the direction 15v due to magnetization alignment and support. The elements of the microstructures or the microstructures themselves interact without contact, so that distances in the range of a few micrometers to several millimeters can be bridged. The exact maximally transmittable force or the maximally bridgeable distance essentially depends on the dimensioning of the magnets 10 and 15. In the above ranges, for example, it was assumed that the individual magnets have an edge length in the range of 20 micrometers to 500 micrometers or arrays are formed from such permanent-magnetic elements. The greater the force to be transmitted or the greater the distance to be bridged, the larger the magnets 10 and 15 are generally dimensioned.
[0042] For the parallel magnetized cube-shaped magnets in
[0043] However, the displacement used for maximum modulation of the force also scales with its size. For an edge length of 50 μm, a displacement of at least 80 μm is used, for an edge length of 100 μm, a displacement of at least 135 μm. The optimum size of the micromagnets is therefore also determined by the displacement available (specified by the actuator used). In order to be able to transmit the greatest possible forces even with small magnets or small displacements, using arrays of permanent-magnet microstructures is an option.
[0044] An example of such a combination is shown in
[0045] The result of the numerical modulation of the array arrangement 10′/15′ from
[0046] According to these results, a lateral displacement of max. 50 μm and a lateral force of up to 430 N/m.sup.2 can thus modulate a vertical force by up to 975 N/m.sup.2. The force is thus amplified by a factor of approx. 2. In the technical implementation, the suspension and guidance of the arrays are of particular importance. While the spring stiffness in the direction of lateral displacement should be chosen to be small so as not to have to apply unnecessarily high forces, the vertical spring stiffness should be chosen to be as stiff as possible so as not to lose force or deflection in the vertical direction due to the flexibility of the array, which is assumed to be fixed here. In addition, the non-driven array is prevented from moving along in the drive direction.
[0047]
[0048] In
[0049] Taking advantage of the transmitted torque, other geometries can be found for converting a linear motion of the permanent-magnetic structure 10 into a tilting motion of the permanent-magnetic structure 15. Examples of this are shown in
[0050] The geometries shown here are abstractions of the principle of action to classify the possible implementations of magnetic force coupling. The magnets are to be seen as placeholders for arbitrarily implemented permanent-magnetic microstructures. In addition to variations in shape and aspect ratio, designs using micromagnet arrays are particularly advantageous.
[0051] In
[0052] In
[0053] Furthermore, the implementations of the magnetic force coupling are not limited to a parallel magnetization of the magnetic structures 10′/15′ or 10/15 used. For the force couplings listed abstractly in
[0054] According to embodiments, the magnetic coupling is not limited to a transmission of forces through free space or ambient atmosphere, as assumed in the previous embodiments. Most of the materials used in microsystem technology have a negligible influence on the magnetic field. This allows the advantage of contactless force transmission to be further exploited in order to transmit forces through existing structures that exclude contact mechanical transmission, for example.
[0055] Such an example of force coupling within a medium 17 is shown in
[0056] Another example of a transmission of a force or a mechanical signal from outside into a closed system (cf. system boundary 18, within which a fluid or a gas atmosphere 17 (alternatively evacuated atmosphere/vacuum) may prevail) is shown in
[0057] It should be noted at this point that, of course, magnetic coupling is not limited to the boundaries of a component. The concepts described can also be used for contactless transmission of forces or displacements between different components. A special case here is the coupling of a microsystem with a macroscopic component by means of permanent-magnetic structures for the transmission of forces or displacements. Here again, the transmission through existing structural materials (which serve, for example, to encapsulate the components, as shown in
[0058] Embodiments may be applied in a variety of microelectromechanical systems where drive or sensor concepts have previously reached their limits. The invention described here allows the direction of force and deflection to be redirected, and geometric restrictions can thus be mitigated. In particular, the use as a lateral-vertical transducer in laterally acting drives for generating vertical deflections is especially advantageous. Applications that entail large vertical deflections, such as micromirrors and/or microloudspeakers, for example, can benefit from this.
[0059] Even though the above embodiments have always assumed a movement of the second array 10 as a result of a movement of the first array 15, it should be noted at this point that instead of the movement of the second array 10, an actuation in the sense of coupling in a force can also take place.
[0060] Further embodiments are explained below:
[0061] According to a first embodiment, the system comprises at least two spaced-apart permanent-magnetic arrangements comprising individual micromagnets or an array of micromagnets, wherein a change in position of the micromagnets of one permanent-magnetic arrangement, thanks to the magnetic force coupling, causes a change in position of the micromagnets in a second permanent-magnetic arrangement or a change in the forces acting on the second permanent-magnetic arrangement.
[0062] According to embodiments, the change in position of the micromagnets of the first permanent-magnetic arrangement is caused by one or more micromechanical actuators integrated at substrate level or by an external device.
[0063] According to embodiments, the individual micromagnets within a permanent-magnetic arrangement are rigidly connected to one another.
[0064] According to alternative embodiments, the individual micromagnets within a permanent-magnetic arrangement are independently movable (i.e., individually coupled).
[0065] According to an embodiment, the number, shape, size and arrangement of the micromagnets of the at least two permanent-magnetic arrangements may differ (cf.
[0066] According to embodiments, the elements of the permanent-magnetic arrangement(s) explained above are arranged in such a way that a kind of comb-shaped structure is formed. There may be a repeat spacing of the individual elements, for example, wherein this may be constant, for example (range between 10 μm and 300 μm). Further, according to additional embodiments, it is also possible to have a periodicity with a repeat spacing in a second direction, so that e.g. instead of comb-shaped structures in two dimensions, regularly arranged cubes are formed per array.
[0067] Another embodiment relates to a method for manufacturing the permanent-magnetic structures. The permanent magnets or micromagnet arrays are manufactured on planar substrates by agglomeration of powder using, for example, ALD in a parallel manufacturing process. In accordance with further embodiments, another type of deposition or another manufacturing method, such as sintering, is of course also conceivable. Even though embodiments of the present invention have been explained in particular with reference to apparatus, it should be noted that the description of an apparatus feature can be understood to be a description of a method feature.
[0068] While this invention has been described in terms of several embodiments, there are alterations, permutations, and equivalents which will be apparent to others skilled in the art and which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and compositions of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.
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