Microstructured fluid flow control device

Abstract

A microstructured fluid flow control device includes a substrate with a piezo-actuated first membrane arranged on a first substrate side, and a fluid channel that extends through the substrate between the first substrate side and an opposite second substrate side. In addition, the microstructured fluid flow control device includes a microvalve that extends through the fluid channel and is configured to close the fluid channel in an unactuated state, and a second membrane arranged on the first substrate side and spaced apart from the membrane and arranged between the fluid channel and the first piezo-actuated membrane. The second membrane is joined to the microvalve and is mechanically biased towards the first membrane so that a biasing force is applied to the microvalve, wherein the biasing force is part of a restoring force that causes the microvalve to close the fluid channel in an unactuated state.

Claims

1. Microstructured fluid flow control device, comprising: a substrate with a piezo-actuated first membrane arranged on a first substrate side, and a fluid channel that extends through the substrate between the first substrate side and an opposite second substrate side, a microvalve that extends through the fluid channel and is configured to close the fluid channel in an unactuated state, and a second membrane arranged on the first substrate side and spaced apart from the first membrane and arranged between the fluid channel and the first piezo-actuated membrane, wherein the second membrane is joined to the microvalve and is mechanically biased towards the first membrane so that a biasing force is applied to the microvalve, wherein the biasing force is part of a restoring force that causes the microvalve to close the fluid channel in an unactuated state.

2. Microstructured fluid flow control device according to claim 1, wherein the microvalve is arranged with respect to a fluid flow direction such that a fluid flowing in this fluid flow direction applies a fluid pressure force to the microvalve, wherein the fluid pressure force acts on the microvalve in addition to the biasing force, wherein the biasing force and the fluid pressure force are part of the restoring force that causes the microvalve to close the fluid channel in an unactuated state.

3. Microstructured fluid flow control device according to claim 1, wherein the microvalve is arranged with respect to a fluid flow direction such that a fluid flowing in this fluid flow direction applies a fluid pressure force to the second membrane, wherein this fluid pressure force acts on the microvalve joined to the second membrane in addition to the biasing force, wherein the biasing force and the fluid pressure force are part of the restoring force that causes the microvalve to close the fluid channel in an unactuated state.

4. Microstructured fluid flow control device according to claim 1, wherein the piezo-actuated first membrane is configured, in an actuated state, to be deflected towards the second membrane and to move the microvalve contrary to the restoring force so that the microvalve releases the fluid channel.

5. Microstructured fluid flow control device according to claim 4, wherein the piezo-actuated first membrane is configured, in an actuated state, to directly come in contact with the second membrane and to deflect the same in order to move the microvalve joined thereto contrary to the restoring force.

6. Microstructured fluid flow control device according to claim 1, wherein the microvalve comprises a valve disc and a valve shaft arranged thereon, wherein the valve disc is arranged on the second substrate side, and wherein the valve shaft extends through the fluid channel towards the first substrate side.

7. Microstructured fluid flow control device according to claim 6, wherein a portion of the valve shaft extends through the second membrane so that this portion is arranged between the first membrane and the second membrane, and wherein the piezo-actuated first membrane is configured, in an actuated state, to come in contact with this portion and to thereby move the valve shaft contrary to the restoring force.

8. Microstructured fluid flow control device according to claim 7, wherein, in an unactuated state, the piezo-actuated first membrane is spaced apart from the portion of the valve shaft that extends through the second membrane.

9. Microstructured fluid flow control device according to claim 7, wherein the portion of the valve shaft that extends through the second membrane is joined to the first membrane.

10. Microstructured fluid flow control device according to claim 1, wherein the piezo-actuated membrane is mechanically biased in a direction away from the second membrane so that, in an unactuated state, the piezo-actuated first membrane is spaced apart from the second membrane.

11. Microstructured fluid flow control device according to claim 1, wherein the piezo-actuated first membrane comprises one or several ventilation holes.

12. Microstructured fluid flow control device according to claim 1, wherein the microstructured fluid flow control device exclusively comprises non-magnetic materials.

13. Microstructured fluid flow control device according to claim 1, wherein the piezo-actuated first membrane comprises a stroke of 20 μm to 50 μm.

14. Microstructured fluid flow control device according to claim 1, wherein the piezo-actuated first membrane comprises a membrane thickness between 25 μm and 150 μm, and/or wherein the second membrane comprises a membrane thickness between 25 μm and 150 μm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present invention will be detailed subsequently referring to the appended drawings, in which:

(2) FIG. 1 shows a schematic sectional side view of an inventive fluid flow control device according to a first embodiment,

(3) FIG. 2A shows a schematic sectional side view of an inventive fluid flow control device according to a first embodiment in an unactuated state,

(4) FIG. 2B shows a schematic sectional side view of an inventive fluid flow control device according to a first embodiment in an actuated state,

(5) FIG. 3A shows a schematic sectional side view of an inventive fluid flow control device according to a first embodiment in an unactuated state,

(6) FIG. 3B shows a schematic sectional side view of an inventive fluid flow control device according to a first embodiment in an actuated state,

(7) FIG. 4A shows a schematic sectional side view of an inventive fluid flow control device according to a first embodiment in an unactuated state, wherein the microvalve is configured as an inlet valve,

(8) FIG. 4B shows a schematic sectional side view of an inventive fluid flow control device according to a first embodiment in an unactuated state, wherein the microvalve is configured as an outlet valve,

(9) FIG. 5 shows a characteristic actuator curve of an inventive fluid flow control device,

(10) FIG. 6 shows a pressure/throughput diagram of an inventive fluid flow control device,

(11) FIG. 7A shows a schematic sectional side view of an inventive fluid flow control device according to a second embodiment in an unactuated state, and

(12) FIG. 7B shows a schematic sectional side view of an inventive fluid flow control device according to a second embodiment in an actuated state.

DETAILED DESCRIPTION OF THE INVENTION

(13) In the following, examples are described in more detail with respect to the drawings, wherein elements having the same or similar functions are provided with the same reference numerals.

(14) FIG. 1 shows an inventive microstructured fluid flow control device 100 according to a first example.

(15) The fluid flow control device 100 comprises a substrate 110. The substrate 110 may be a semiconductor substrate and may comprise silicon, for example, or the substrate 110 may be a metal substrate and may comprise metal, such as stainless steel or titanium, or may be manufactured thereof. The substrate 110 comprises a first substrate side 111 and an opposite second substrate side 112. The substrate 110 comprises a first main surface 121 located on the first substrate side 111 and a second main surface 122 located on the opposite second substrate side 112. A piezo-actuated first membrane 101 is arranged on the first substrate side 111. For example, as is exemplarily illustrated, the piezo-actuated first membrane 101 may be arranged on the first main surface 121 of the substrate 110, e.g. by means of bonding. Thus, the first main surface 121 of the substrate 110 may define a horizontal first substrate plane L1, wherein the piezo-actuated first membrane 101 would be arranged in this first substrate plane L1 in this case.

(16) The piezo-actuated first membrane 101 may comprise a piezo element 108. The piezo element 108 may be arranged on the side of the first membrane 101 facing away from the substrate 110. By applying an (e.g. negative) electric voltage to the piezo element 108, it expands laterally, which leads to the first membrane 101 curving upwards, i.e. in the direction away from the substrate 110. By applying an electric voltage opposite in value (e.g. positive) to the piezo element 108, the piezo element 108 contracts laterally, which leads to the first membrane 101 deflecting downwards, i.e. in the direction towards the substrate 110.

(17) The fluid flow control device 100 further comprises a fluid channel 104. The fluid channel 104 extends through the substrate 110 between the first substrate side 111 and the opposite second substrate side 112. The fluid channel 104 may extend between the first substrate side 111 and the second substrate side 112 vertically and as straight as possible as well as continuously.

(18) In addition, the fluid flow control device 100 comprises a microvalve 105. The microvalve 105 comprises a valve portion 105A that is fully located within the fluid channel 104 and fully extends through the fluid channel 104.

(19) The microvalve 105 is configured as a normally-closed valve. That is, the microvalve 105 is configured to close the fluid channel 104 in an unactuated state.

(20) To this end, the inventive fluid flow control device 100 comprises a second membrane 102.

(21) The piezo-actuated first membrane 101 and/or the biased second membrane 102 may comprise metal or a semiconductor, e.g. silicon, or may be manufactured thereof. The second membrane 102 is also arranged on the first substrate side 111. For example, a recess 106 may be structured in the first main surface 121 of the substrate 110. The second membrane 102 may be arranged in this recess 106. The recess 106 may define a horizontal second substrate plane L2, wherein the second membrane 102 is arranged in this second substrate plane L2. Stated in more general terms, the substrate 110 may comprise on the first substrate side 111 one or several horizontal substrate planes L1, L2 that may be spaced apart from each other in the vertical direction, and wherein the first membrane 101 is arranged in the first substrate plane L1 and the second membrane 102 is arranged in the second substrate plane L2.

(22) The first substrate plane L1 may be further spaced apart from the second substrate side 112 than the second substrate plane L2. In principle, the first substrate plane L1 and the second substrate plane L2 may be vertically spaced apart from each other. Thus, the first membrane 101 may also be arranged vertically spaced apart from the second membrane 102. The fluid channel 104 is arranged below the second membrane 102, i.e. the second membrane 102 is arranged between the first fluid channel 104 and the first piezo-actuated membrane 101.

(23) According to this first embodiment, the second membrane 102 is joined to the microvalve 105, according to the invention. That is, the microvalve 105 and the second membrane 102 are firmly connected to each other, advantageously permanently and inseparably. For example, the microvalve 105 may be bonded, glued, or welded to the second membrane 102.

(24) In addition, according to the invention, the second membrane 102 is mechanically biased, that is upwards, i.e. towards the first membrane 101. Due to this mechanical bias, a biasing force F.sub.V is applied to the microvalve 105, wherein this biasing force F.sub.V is part of a restoring force F.sub.R that causes the microvalve 105 to close the fluid channel 104 in an unactuated state. That is:

(25) F.sub.R=F.sub.V+X,

(26) wherein X=0 or may be an optional further force component.

(27) The piezo-actuated first membrane 101 is herein also referred to as actuator membrane. The bias second membrane 102 joined to the microvalve 105 is herein also referred to as valve membrane. According to examples, the first membrane 101 may also be mechanically biased.

(28) Fundamentally, mechanically biasing the membrane 101, 102 may be carried out according to a method as described in U.S. Pat. No. 9,410,641 B2 and whose content is explicitly incorporated herein by reference.

(29) FIGS. 2A and 2B show a further example of an inventive fluid flow control device 100 with two membranes 101, 102 according to the first embodiment. FIG. 2A shows the fluid flow control device 100 in an unactuated state, and FIG. 2B shows the fluid flow control device 100 in an actuated state.

(30) The fluid flow control device 100 illustrated here comprises a piezo-actuated first membrane 101 arranged on the first substrate side 111 and in a first horizontal substrate plane L1. In addition, the fluid flow control device 100 comprises a mechanically biased second membrane 102 arranged on the first substrate side 111 and in a second horizontal substrate plane L2.

(31) As can be seen in FIG. 2A, the first membrane 101 may also be mechanically biased in addition to the second membrane 102. Due to the bias, the first membrane 100 may extend at least in portions beyond the first substrate plane L1. This increases a distance between the first membrane 101 and the second membrane 102.

(32) The second membrane 102 is also mechanically biased, that is towards the first membrane 101, i.e., in principle, the second membrane 102 may be biased in the same direction as the first membrane 101. The bias of the second membrane 102 directly acts on the microvalve 105 joined to the second membrane 102 and pulls the microvalve 105 upwards, i.e. towards the first membrane 101. Thus, the microvalve 105 closes the fluid channel 104 in the unactuated state shown in FIG. 2A.

(33) FIG. 2B illustrates an actuated state of the fluid flow control device 100. Here, an electric voltage of +300 V is exemplarily applied to the piezo element 108. As a consequence, the piezo element 108 contracts and deflects the first membrane 101 downwards, i.e. towards the second membrane 102.

(34) The first membrane 101 contacts the second membrane 102 and consequently deflects the second membrane 102. Here, the actuation force F.sub.B applied to the first membrane 101 by the piezo element 108 is larger than the restoring force F.sub.R that acts on the microvalve 105. This is why the microvalve 105 is actuated contrary to the restoring force F.sub.R, which subsequently releases, or opens, the fluid channel 104.

(35) If the electric voltage is no longer applied, the first membrane 101 returns to its unactuated initial position shown in FIG. 2A. The size of the restoring force F.sub.R again exceeds the size of the actuation force F.sub.P so that the microvalve 105 also returns to its unactuated initial position shown in FIG. 2A and again closes the fluid channel 104. This function is also referred to as normally-closing.

(36) FIGS. 3A and 3B show a further example of an inventive fluid flow control device 100 with two membranes 101 and 102 according to the first embodiment. FIG. 3A shows the fluid flow control device 100 in an unactuated state, and FIG. 3B shows the fluid flow control device 100 in an actuated state.

(37) In the variation shown here, the microvalve 105 comprises a valve disc 116 and a valve shaft 117 arranged thereon. The valve disc 116 is arranged on the second substrate side 112 that faces away from the first membrane 101, and closes the fluid channel 104 in the unactuated state. More precisely, the valve disc 116 closes a fluid channel opening arranged on the second substrate side 112.

(38) The valve shaft 117 extends through the fluid channel 104, starting from the valve disc 116, towards the first substrate side 111 up to the second membrane 102.

(39) In addition to the example shown in FIGS. 2A and 2B, the valve shaft 117 shown in FIGS. 3A and 3B comprises a portion 115 that extends through the second membrane 102 and projects beyond the second membrane 102 towards the first membrane 101. That is, this portion 115 of the valve shaft 117 that extends through the second membrane 102 is arranged between the first membrane 101 and the second membrane 102.

(40) As can now be seen in FIG. 3B, when applying a voltage, the piezo element 108 deflects the first membrane 101 downwards, i.e. towards the fluid channel 104. In this case, the deflected first membrane 101 contacts the portion 115 of the valve shaft 117 that projects through the second membrane 102. The actuation force F.sub.P applied in this case acts directly on the valve shaft 117 via the portion 115 and therefore acts directly on the overall microvalve 105. If the size of the actuation force F.sub.P is larger than the size of the restoring force F.sub.R, the microvalve 105, or the valve disc 116, lifts itself off of the fluid channel 104 and opens the same.

(41) If the electric voltage is no longer applied, the first membrane 101 again returns to the unactuated initial position shown in FIG. 3A. In this case, the size of the restoring force F.sub.R again exceeds the size of the actuator force F.sub.P so that the microvalve 105 also returns to its unactuated initial position shown in FIG. 3A, and the valve disc 116 again closes the fluid channel 104.

(42) FIGS. 4A and 4B again show an inventive fluid flow control device 100 in an unactuated state in order to describe the acting forces in more detail.

(43) In FIG. 4A, the fluid 400 flows from a surrounding area towards the fluid channel 104. Thus, in this example, the fluid channel 104 would be an inlet channel and the microvalve 105 would be configured as an inlet valve. If the microvalve 105 is open, the fluid 400 may enter into a space 402 between the two membranes 102 and the substrate 110, which is also referred to as fluid chamber, and may exit from an outlet channel 401.

(44) In the illustrated case, a fluid force F.sub.F directly acts on the microvalve 105 in addition to the biasing force F.sub.V caused by the bias of the second membrane 102. In the present example, the fluid force F.sub.F directly acts on the valve disc 116 from below, i.e. from the surrounding area, for example. In this case, the fluid force F.sub.F essentially acts in the same direction as the biasing force F.sub.V, Thus, the normally-closing effect is increased, wherein the microvalve 105 closes the fluid channel 104 in an unactuated state. In this case, the restoring force F.sub.R is essentially made up of the biasing force F.sub.V and the additionally acting force F.sub.F, i.e.:
F.sub.R=F.sub.V+F.sub.F

(45) Stated in more general terms, the microvalve 105 may be arranged with respect to the fluid flow direction such that a fluid 400 that flows in this fluid flow direction applies a fluid pressure force F.sub.F to the microvalve 105, wherein the fluid pressure force F.sub.F acts on the microvalve 105 in addition to the biasing force F.sub.V and in the same direction as the biasing force F.sub.V, wherein the biasing force F.sub.V and the fluid pressure force F.sub.F are part of the restoring force F.sub.R that causes the microvalve 105 to close the fluid channel 104 in an unactuated state.

(46) Thus, in the inlet direction, the fluid flow control device 100 is not only normally-closing but also self-blocking.

(47) In FIG. 4B, the fluid 400 flows from the surrounding area through an inlet 404 into the space 402, which is also referred to as fluid chamber, between the membrane 102 and the substrate 110. Thus, in this example, the fluid channel 104 would be an outlet channel and the microvalve 105 would be configured as an outlet valve.

(48) In this case, a k-th part F.sub.K of the fluid force F.sub.F acts from above on the microvalve 105, more particularly on the valve disc 106, i.e. from the first substrate side 111, contrary to the restoring force F.sub.R. An m-th part F.sub.M of the fluid force F.sub.F acts from below on the second membrane 102 in the same direction as the restoring force F.sub.R, i.e. towards the first membrane 101.

(49) In an example, the second membrane 102 comprises a first attack surface A.sub.M for the fluid 400, and the valve disc 116 comprises a second attack surface Av for the fluid 400. In this case, the second membrane 102 provides a larger attack surface for the fluid 400, i.e. A.sub.M>A.sub.V. The fluid pressure P.sub.RA that acts on the respective surface A.sub.M or Av generates a proportional fluid force, i.e. F.sub.M=P.sub.Fluid.Math.A.sub.M and F.sub.K=P.sub.Fluid.Math.A.sub.K. Since A.sub.M>A.sub.V at the same fluid pressure P.sub.Fluid, F.sub.M>F.sub.V also applies. That is, the force F.sub.M that acts on the second membrane 102 towards the restoring force F.sub.R is larger than the force F.sub.V that acts on the microvalve 105 contrary to the restoring force F.sub.R.

(50) Stated in more general terms, the microvalve 105 may be arranged with respect to a fluid flow direction such that a fluid 400 flowing in this fluid flow direction applies a fluid pressure force F.sub.M to the second membrane 102, wherein this fluid pressure force F.sub.M acts on the microvalve 105 joined to the second membrane 102 in addition to the biasing force F.sub.V and in the same direction as the biasing force F.sub.V, wherein the biasing force F.sub.V and the fluid pressure force F.sub.M are part of the restoring force F.sub.R that causes the microvalve 105 to close the fluid channel 104 in an unactuated state.

(51) Thus, the present inventive fluid flow control device 100 is normally-closing and self-blocking both the inlet direction and in the outlet direction.

(52) In the examples discussed before with respect to FIGS. 2A to 3B, the piezo-actuated first membrane 101 was spaced apart from the portion 115 of the valve shaft 117 that extends through the second membrane 102 in an unactuated state. For example, the piezo-actuated first membrane 101 may be mechanically biased in a direction away from the second membrane 102 so that the piezo-actuated first membrane 101 is spaced apart from the second membrane 102 in an unactuated state. This distance allows for greater manufacturing tolerances when biasing the first membrane 101 and/or when biasing the second membrane 102, however, it leads to a certain idle travel when actuating the free flow control device 100, or the microvalve 105.

(53) Alternatively, it would also be conceivable that the portion 115 of the valve shaft 117 that extends through the second membrane 102 is joined to the first membrane 101. That is, the portion 115 could be firmly connected to the first membrane 101, advantageously permanently and inseparably. In this case, the idle travel would not exist, even with a biased first membrane 101, and the microvalve 105 could be deflected by means of the piezo-actuated first membrane 101 in an idle travel-free manner, so to speak.

(54) FIG. 5 shows a diagram for illustrating the behavior of the piezo-actuated first membrane 101, i.e. the vertical deflection of the first membrane 101 as a reaction to applying an electric voltage to the piezo element 108. The electric voltage is plotted on the abscissa, and the vertical deflection (in the z-direction) is plotted on the ordinate. The diagram shows a typical characteristic actuator curve (vertical deflection with respect to electric voltage at the piezo ceramic) of a normally-closed microvalve 105 that may be used in the inventive fluid flow control device 100.

(55) When applying a positive voltage, the first membrane 101 is deflected downwards, that is towards the second membrane 102 (cf. FIGS. 2A to 4B). When applying a negative voltage, the first membrane 101 is deflected upwards, i.e. away from the substrate 110. In this case, the force/deflection capacity is symmetrical. Due to the piezophysics, in contrast to the positive voltage, a relatively low negative voltage can be applied before the piezo repolarizes.

(56) However, in the diagram illustrated in FIG. 5, the above-mentioned idle travel can be seen. With negative voltages, the first membrane 101 is deflected upwards and away from the microvalve 105 and shows a characteristic curve that is not affected by the force. With positive voltages, the first membrane 101 contacts the second membrane 102 (FIGS. 2A and 2B), or the valve shaft portion 115 (FIGS. 3A and 3B), and opens the microvalve 105 downwards contrary to the restoring biasing force F.sub.V of the second membrane 102, i.e. towards the second substrate side 112, which leads to a flatter characteristic curve. In addition, what can be seen is the idle travel (approximately 3 μm to 5 μm) up to the contact of the second membrane 102, or the valve shaft portion115, before the characteristic curve breaks off.

(57) As initially mentioned, the microvalve 105 may be moved between two extreme positions, i.e. between a fully open and a fully closed position. Due to the active drive by means of the piezo-actuated first membrane 101, the microvalve 105 may further be moved continuously between these two extreme positions, which is why the throughput, or the throughput amount, of a fluid flowing through the microvalve 105 may also be continuously controlled. That is, the inventive fluid flow control device 100 may continuously control a fluid flow.

(58) That is, beside opening or closing the fluid channel 104, a functional feature of the inventive fluid flow control device 100 may also be the representation of a controllable flow resistor in the sense of a proportional valve. By moving the microvalve 105 to any position between the open and closed state, a corresponding operating point in the pressure/throughput diagram (cf. FIG. 6) may be selected.

(59) FIG. 6 shows a typical pressure/throughput diagram of a microvalve 105 when used in an inventive through flow control device 100, the fluid being water. The throughput is plotted for different differential pressures across the microvalve 105 as a function of the electric voltage applied to the piezo element 108.

(60) FIG. 7A and 7B show a second embodiment of an inventive fluid flow control device 200, this embodiment only comprising a single membrane 201. FIG. 3A shows the fluid flow control device 200 in an unactuated state, and FIG. 3B shows the fluid flow control device 200 in an actuated state.

(61) Elements having the same or a similar function as in the above-described first embodiment (FIGS. 1 to 4B) are represented with the same reference numerals, which is why a description of the same is omitted. Nevertheless, all elements, features, and functions described with respect to the first embodiment also apply to the subsequently discussed second embodiment. Thus, what is subsequently describes are only the differences between the second embodiment shown in FIG. 7A and 7B and the first embodiment shown in FIGS. 1 to 4B.

(62) The embodiment shown in FIG. 7A and 7B differs in that the inventive microstructured fluid flow control device 200 only comprises one membrane 201 that is mechanically biased and joined to the microvalve 105, and also comprises a piezo element 108. That is, the membrane 201 simultaneously acts as the actuator membrane and as the valve membrane. The membrane 201 may comprise metal or a semiconductor, such as silicon, or be manufactured therefrom.

(63) The illustrated microstructured fluid flow control device 200 comprises a substrate 110 with a piezo-actuator 201 arranged on a first substrate side 111, and a fluid channel 104 that extends through the substrate 110 between the first substrate side 111 and an opposite substrate side 112.

(64) The microstructured fluid flow control device 200 further comprises a microvalve 105 with a valve disc 116 and a valve shaft 117 arranged thereon, wherein the valve disc 116 is arranged on the second substrate side 112 facing away from the membrane 201, and wherein the valve shaft 117 extends through the fluid channel 104 towards the membrane 201 arranged on the first substrate side 111. That is, the valve shaft 117 is arranged at least in portions on the first substrate side 111, and the valve disc 116 is arranged on the opposite second substrate side 112. In the unactuated state, the valve shaft 116 may close a fluid channel opening located on the second substrate side 112.

(65) According to the invention, the piezo-actuated membrane 201 is joined, or fixedly connected, to the microvalve 105, in particular to the valve shaft 117. Advantageously, the membrane 201 is connected permanently and inseparably to the microvalve 105, or the valve shaft 117.

(66) In addition, the piezo-actuated membrane 201 is mechanically biased, that is towards a direction facing away from the substrate 110, so that the membrane 201 curves away from the substrate 110 in an unactuated state (FIG. 7A) and optionally extends beyond the substrate plane L1. Due to the mechanical bias, a biasing force F.sub.V is here again applied to the microvalve 105, wherein the biasing force F.sub.V is part of a restoring force F.sub.R that causes the valve disc 116 to close the fluid channel 104 in an unactuated state.

(67) FIG. 7B shows the microstructured fluid flow control device 200 of FIG. 7a in an actuated state. When applying an electric voltage, here exemplarily having a magnitude of +300 volts, the piezo element 108 deflects the membrane 201 downwards, i.e. towards the substrate 110, or the fluid channel 104. The actuation force F.sub.P of the piezo element 108 acts contrary to the restoring force F.sub.R, which may be made up of the biasing force F.sub.V of the membrane and a fluid force F.sub.F that may be present at the microvalve 105.

(68) If the actuation force F.sub.P of the piezo element 108 exceeds the resorting force F.sub.R in magnitude, the membrane 201 deflects the microvalve 105 downwards, i.e. towards a direction away from the fluid channel 104, so that the microvalve 105 lifts off from the fluid channel 104 and opens, or releases, the fluid channel 104.

(69) That is, in an unactuated state, the piezo-actuated membrane 201 may be configured to be deflected towards the fluid channel 104 and to move the microvalve 105 opposite the restoring force F.sub.R in a direction away from the fluid channel 104 so that the microvalve 105 releases the fluid channel 104.

(70) In the second embodiment illustrated in FIGS. 7A and 7B, the membrane 201 may also be arranged in a first horizontal substrate plane L1 that may coincide with the first main surface 121 of the substrate 110. That is, the membrane 201 may be arranged on the first main surface 121 of the substrate 110 on the first substrate side 111.

(71) A recess 106 that extends towards the second substrate side 112 and defines a second horizontal substrate plane L2 may be structured in the first main surface 121 of the substrate 110. In this case, the recess 106 between the membrane 201 on the first substrate plane L1 and the structured portion of the substrate 110 of the second substrate plane L2 may also be referred to as fluid chamber into which the fluid flows if the microvalve 105 is configured as an inlet valve, or from which the fluid flows out if the microvalve 105 is configured as an outlet valve (cf. FIGS. 4A and 4B).

(72) Representing all embodiments described herein, FIG. 7B exemplarily shows that, a recess 107 which extends towards the first substrate side 111 and in which the microvalve 105, or the valve disc 116, may be arranged may also be provided on the second substrate side 112, or in a second main surface 122 of the substrate 110, for example. For example, this recess 107 may be structured into the second main surface 122 of the substrate 110. The depth of the recess 107 may approximately correspond to the vertical stroke of the microvalve 105 so that the microvalve 105, or the valve disc 116, is still located within the recess 107 even when fully deflected. This provides a mechanical stop protection for the microvalve 105.

(73) Also representing all described embodiments, FIG. 7B exemplarily shows that a sealing valve seat 109 may be provided at an opening of the fluid channel 104 that faces the valve disc 116. For example, this may be a non-adhesive valve seat with a lower release force, which may comprise one or several elastomers.

(74) In all embodiments, the microvalve 105 may be linearly moveable between an open position and a closed position. The microvalve 105 may be brought into at least two extreme positions, i.e. a fully closed position in which the fluid channel 104 is as fluid-tight as possible, and a fully open position in which the fluid channel 104 is as open as possible. In this case, the inventive microstructured fluid flow control device 100, 200 may actively control the fluid flow at least between these two positions. Alternatively or in additionally, the microvalve 105 may be moved gradually in at least one further position or continuously between the two extreme positions (open/closed). In this case, the inventive microstructured fluid flow control device 100, 200 may gradually or continuously control the fluid flow in the sense of a proportional valve.

(75) In addition, it is conceivable in all embodiments that the piezo-actuated membrane 101, 201 comprises one or several ventilation holes. Due to additional ventilation holes in the piezo-actuated membrane 101, 201, a pressure compensation may be achieved from the air-filled chamber (recess 106) between the piezo-actuated membrane 101 and the second membrane 102 (first embodiment), or between the piezo-actuated membrane 201 and the substrate 110 (second embodiment), with respect to the atmosphere above the piezo-actuated membrane 101 201, leading to a stabilization of the zero position of the drive for fluctuating environmental conditions.

(76) In addition, it is conceivable in all embodiments that the microstructured fluid flow control device 100, 200 exclusively comprises non-magnetic materials. This provides an MRT capability due to non-magnetic materials (e.g. titanium) and actuator principles.

(77) In addition, it is conceivable in all embodiments that the micro-actuated membrane 101, 201 comprises a vertical stroke of 20 μm to 50 μm. In addition, it is conceivable that the piezo-actuated membrane 101, 201 comprises a membrane thickness between 25 μm and 150 μm, and/or that the second membrane 102 comprises a membrane thickness between 25 μm and 150 μm.

(78) For example, the inventive fluid flow control device 100 200 may be used in the following technical areas:

(79) Medical Technology: Implants Sphincter, penile prosthesis Extracorporeal medical devices: Drug dosing, intravenous, subcutaneous

(80) Industry: Oil Dosing Microhydraulics/micropneumatics Shut-off valve (failsafe)

(81) The invention shall again be summarized below in other words:

(82) An aspect of the present invention is a piezo-electrically driven, normally-closing and self-blocking microvalve 105 in a small and particularly flat design. That is, in the currentless state, the valve 105 is closed and the fluid pressure F.sub.F that is present additionally enhances the closing force.

(83) The principle is based on a deflection of the vertical direction of action of a piezo membrane converter 101 through a transmission element 117 on a non-inversely opposite seal seat 109, creating the possibility to use the restoring force F.sub.R of a non-electrically actuated (i.e. unactuated) piezo membrane converter 101 towards its zero position in the balance of forces. This passive restoring force F.sub.R that is achieved through a spring membrane 102 and a corresponding biasing method is used in the new invention to close the valve 105 in the currentless state.

(84) A seal element (e.g. a valve disc) 116 that is fixedly connected to a transmission element (e.g. a valve shaft) 117 is pulled in the closing direction against a seal seat 109 through a biased valve membrane 102 according to a restoring spring. The valve membrane 102 is joined to the seal element 116 and the valve base body 105 in a fluidically tight manner. A further membrane, i.e. the actuator membrane 101, is joined to the base body 110 in the plane L2 above the valve membrane 102. A piezo-disc actuator 108 may be applied to this actuator membrane 101, e.g. by means of adhesion, using an electric biasing assembly according to U.S. Pat. No. 9,410,641 B2 so that a finite residual slit remains between the actuator membrane 101 and the transmission element 117 in the currentless state of the piezo-actuator 108.

(85) Thus, in the currentless state (cf. FIG. 3A, for example), the seal seat 109 of the valve 115 is closed by the seal element 116, corresponding to a normally-closed state. In addition, a fluid pressure F.sub.F acts on the seal element 116 from the inlet side of the valve 115 as a further closing force component.

(86) In the powered state, i.e. when applying a positive electric voltage to the piezo ceramic 108 (cf. FIG. 3B, for example), that actuator membrane 101 is deformed towards the transmission element 117 and moves the same away from the seal seat 109 into an opening direction if the force F.sub.P of the piezo membrane converter 101 acting vertically on the transmission element 117 is larger than the restoring forces F.sub.R of the valve membrane 102 and the fluid pressure F.sub.F on the seal element 116. This may be achieved by an adapted actuator design with respect to the specification of the corresponding operating region.

(87) A further embodiment of the valve 115 may be such that the transmission element 117 is still directly welded to the actuator membrane 101 and that the slit is therefore omitted.

(88) A further embodiment (cf. FIGS. 7A and 7B, for example) of the valve 115 may be such that the valve membrane 102 is omitted and that the transmission element 117 is permanently kept in the closed position through a welding/bonding connection to the actuator membrane 101 due to the bias, as long as it is currentless.

(89) As can be seen in FIGS. 7A and 7B, the transmission element 117 is directly joined to the actuator membrane 101 and, in the currentless state, is kept closed due to the bias. On the other hand, it is opened by applying a positive electric field at the piezo-actuator 108.

(90) Design of the Valve Structure: Foil construction on a solid base body 110 A piezo-actuator 108 as a membrane bending transducer A deflection unit/valve seal element 116, 117 in different versions An intermediate membrane 102 (also referred to as valve membrane) with the following purpose: Biasing the transmission/seal element 116, 117 against the valve seat 109 Pressure compensation due to smaller effective area for fluid pressure Stroke optimization.fwdarw.the actuator 101 may be designed independently of the restoring membrane 102 Materials: metals, in particular spring steel and titanium, plastics Manufacturing method: Base body 110: machining (turning, milling), additive manufacturing Foils: structured etching Joining method: adhesion, soldering (laser, resistance welding, ultra-sonic, e-beam) Seal seat: hard-hard or possibly soft seal

(91) Technical Properties: No energy consumption in the closed state.fwdarw.normally-closed Flat design: typically structural height of less than 5 mm Footprint: circular base body diameter of approximately less than 25 mm, e.g. 20 mm or 15 mm Typical thicknesses of the valve membrane and actuator membrane 101, 102, 201 are 25 μm to 150 μm, for example Typical piezo-actuator thicknesses, e.g. 100 μm-200 μm Normally-closing on both sides (forward and backward, cf. characteristic flow curve) Self-blocking: fluid pressure acts in both directions in a blocking manner on the seal element 116 and/or translated via the valve membrane 102 on the transmission element 117 Low leakage rate in the closed state Low flow resistance in the open state Short switching times due to piezo-actuators: from closed to open in t <5 ms MRT capability due to non-magnetic materials (titanium) and actuator principles Exemplary actuator design of the piezo membrane actuator system: Vertical stroke in the opening direction at a positive voltage (i.e. downwards): 20 μm to 50 μm Actuator force/blocking pressure 30 kPa to 100 kPa Pressure compensation: due to ventilation holes in the actuator membrane 101, the membrane remains stable in the original zero position in case of fluctuations of the ambient pressure

(92) No energy consumption in the closed state at a small installation size, and non-magnetic materials allow the use in active implants. There is no known technical solution for this so far.

(93) (+++) no energy consumption in the closed state

(94) (+++) normally-closing on both sides

(95) (+++) self-blocking functionality

(96) (+++) MRT capability due to non-magnetic materials (titanium) and actuator principles

(97) (++) flat structural size (structural height <5 mm)

(98) (++) short switching times (a few milliseconds)

(99) (+) low leakage rate in the closed space

(100) (+) low flow resistance in the open state (high flow rate)

(101) While this invention has been described in terms of several embodiments, there are alterations, permutations, and equivalents that 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.