BACKGROUND

Pop-up microelectromechanical systems (MEMS) are formed by a novel fabrication process capable of creating complex millimeter-scale articulated structures comprising rigid segments adhered to a flexible layer (to enable flexing of the structure at the gaps between the rigid segments). The structures can be fabricated via bulk machining, lamination, and assembly by folding, as described in US Patent No. 8,834,666 B2, which is incorporated by reference in its entirety herein.

FIG. 1 shows a generalized process flow for pop-up MEMS fabrication. The process can include the following steps:

a) first, printed-circuit-board (PCB) lithography 11 can optionally be used to form patterns for producing electrically conductive pathways for apparatus that incorporate circuits;

b) in a first laser-machining step 12, a laser is used to cut patterns for other layers in the laminate;

c) next, pin alignment 13 is used to align the layers in the laminate structure by passing pins through carefully positioned orifices in each layer; d) low-profile components that are suitable for lamination can optionally be inserted into the laminate structure via a first pick-and-place procedure 14; e) the resulting laminate is then press cured 15;

f) a second-laser machining step 16 is then used to cut bridges in the

laminate structure to release the pop-up assembly from the cured laminate structure;

g) multiple iterations of steps c-f can be performed;

h) in processes that incorporate solder reflow, a solder paste stencil 17 can optionally be used on the released pop-up assembly;

i) in an optional second pick-and-place procedure 18, components that are not suitable for lamination can be inserted into the assembly;

j) the layers of the assembly can then be released {e.g., unfolded) to produce a three-dimensional pop-up assembly 19; k) pick-and-place procedure 18 can be repeated, if necessary, to add additional components after pop-up folding;

1) the arrangement of layers in the pop-up assembly can then be locked 20 by soldering the joints of the assembly via exposure to, e.g., a solder bath, solder paste reflow, or glue application; and

m) in a third laser-machining step 21, a laser is used to sever any remaining bridges or bonds to release the device and any remaining degrees of freedom.

Pop-up MEMS devices can incorporate various types of actuation, including electromagnetic and piezoelectric actuators, as described in PCT Publication No. WO 2015/020952 Al.

SUMMARY

Balloon actuation structures and methods for laminated devices are described herein, wherein various embodiments of the apparatus and methods may include some or all of the elements, features and steps described below.

Balloon actuators can be incorporated into laminated mechanisms by bonding patterned flexible layers with an adhesive trace to form at least one balloon with a central unbonded region that forms a hermetic chamber. At least one of the patterned flexible layers of each balloon can also be bonded selectively to more-rigid parts {i.e., more rigid than the flexible layers) of the laminated mechanism in a configuration such that pressurization of the hermetic chamber(s) produces relative linear or rotational displacement of at least one of the more-rigid parts with respect to another of the more-rigid parts.

The balloon actuation modality described herein further extends the capabilities of pop-up MEMS devices. Balloon actuators can be incorporated directly into pop-up MEMS laminates and powered by hydraulic or pneumatic sources. The elastomeric pneumatic-network (PneuNet-style) actuators described herein can create motion from their asymmetric 3D geometry and/ or from embedded strain- limiting materials. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a general process flow for pop-up MEMS laminate

fabrication.

FIG. 2 shows two patterned flexible sheet layers 24 for forming an actuator comprising a series of interconnected balloons.

FIG. 3 shows diode-pumped-solid-state laser release cuts 25 in the flexible sheet 23 from which the patterns 24 are removed to form the balloons.

FIG. 4 shows inflation of the balloons 26 using a syringe 27 that injects air into the chambers defined by the balloons 26.

FIG. 5 is a sectional view of a laminated pneumatic actuator 22 comprising a series of connected chambers 28 defined by the patterned flexible layers 34 of the balloon 26 in a depressurized state.

FIG. 6 is a sectional view of the laminated pneumatic actuator 22 of FIG. 5 with the connected chambers 28 in a pressurized state created via fluid 38 {e.g., air) injection.

FIG. 7 shows a laminate panel of electrodes 32 with laminate balloon actuators 26 via a top-side view (top), via a bottom-side view with the balloons 26 deflated (middle), and via a bottom-side view with the balloons 26 inflated (bottom).

FIG. 8 is an exploded view of a laminate structure for a balloon-actuated electrode panel showing patterned flexible layers 24, adhesive patterns 34, more- rigid layers 30, and an electrically conductive layer 36.

FIG. 9 is a side sectional view of a folded balloon actuator 22 including more- rigid layers 30 bonded to a balloon 26 in a depressurized state.

FIG. 10 is a side sectional view of the balloon actuator 22 of FIG. 9 with the balloon chamber 28 partially pressurized.

FIG. 11 is a side sectional view of the balloon actuator 22 of FIGS. 9 and 10 with the balloon chamber 28 fully pressurized.

FIG. 12 is a side sectional view of a balloon 26 coupled with the more-rigid layers 30 of a laminate structure 22 to form an actuator that further includes an inextensible flexural layer 36, wherein the balloon 26 is depressurized. FIG. 13 is a side sectional view of the balloon actuator 22 of FIG. 12 with the balloon 26 pressurized.

In the accompanying drawings, like reference characters refer to the same or similar parts throughout the different views; and apostrophes are used to

differentiate multiple instances of the same or similar items sharing the same reference numeral. The drawings are not necessarily to scale; instead, an emphasis is placed upon illustrating particular principles in the exemplifications discussed below.

DETAILED DESCRIPTION The foregoing and other features and advantages of various aspects of the invention(s) will be apparent from the following, more-particular description of various concepts and specific embodiments within the broader bounds of the invention(s). Various aspects of the subject matter introduced above and discussed in greater detail below may be implemented in any of numerous ways, as the subject matter is not limited to any particular manner of implementation. Examples of specific implementations and applications are provided primarily for illustrative purposes.

Unless otherwise herein defined, used or characterized, terms that are used herein (including technical and scientific terms) are to be interpreted as having a meaning that is consistent with their accepted meaning in the context of the relevant art and are not to be interpreted in an idealized or overly formal sense unless expressly so defined herein. For example, if a particular composition is referenced, the composition may be substantially (though not perfectly) pure, as practical and imperfect realities may apply; e.g., the potential presence of at least trace impurities {e.g., at less than 1 or 2%) can be understood as being within the scope of the description. Likewise, if a particular shape is referenced, the shape is intended to include imperfect variations from ideal shapes, e.g., due to manufacturing

tolerances. Percentages or concentrations expressed herein can represent either by weight or by volume. Processes, procedures and phenomena described below can occur at ambient pressure {e.g., about 50-120 kPa— for example, about 90-110 kPa) and temperature {e.g., -20 to 50°C— for example, about 10-35°C) unless otherwise specified.

Although the terms, first, second, third, etc., may be used herein to describe various elements, these elements are not to be limited by these terms. These terms are simply used to distinguish one element from another. Thus, a first element, discussed below, could be termed a second element without departing from the teachings of the exemplary embodiments.

Spatially relative terms, such as "above," "below," "left," "right," "in front," "behind," and the like, may be used herein for ease of description to describe the relationship of one element to another element, as illustrated in the figures. It will be understood that the spatially relative terms, as well as the illustrated configurations, are intended to encompass different orientations of the apparatus in use or operation in addition to the orientations described herein and depicted in the figures. For example, if the apparatus in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term, "above," may encompass both an orientation of above and below. The apparatus may be otherwise oriented {e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Further still, in this disclosure, when an element is referred to as being "on," "connected to," "coupled to," "in contact with," etc., another element, it may be directly on, connected to, coupled to, or in contact with the other element or intervening elements may be present unless otherwise specified.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of exemplary embodiments. As used hierein, singular forms, such as "a" and "an," are intended to include the plural forms as well, unless the context indicates otherwise. Additionally, the terms, "includes," "including," "comprises" and "comprising," specify the presence of the stated elements or steps but do not preclude the presence or addition of one or more other elements or steps. Additionally, the various components identified herein can be provided in an assembled and finished form; or some or all of the components can be packaged together and marketed as a kit with instructions {e.g., in written, video or audio form) for assembly and/ or modification by a customer to produce a finished product.

Formation of Laminate Structures:

The laminate structures described in this section can be used to form the laminated mechanisms described in the following section and the structures to which the laminate balloon structures are bonded.

In particular embodiments, the laminate structure can be a multi-layer, super- planar structure that can be distorted, flexed or folded (these terms may be used interchangeably herein). An embodiment of this structure can be achieved, for example, by forming a five-layer composite with the following sequence of layers: rigid layer 30, adhesive layer 34, flexible layer 24/ 36, adhesive layer 34, and rigid layer 30. The flexible layers 24/36 are substantially less rigid than the rigid layers 30 and can have a rigidity that is at least an order of magnitude {i.e., greater than lOx or greater than lOOx) less than the rigidity of the rigid layers 30; likewise, the flexible layer can have at least 10 times or at least 100 times the flexibility of the rigid layers. In additional embodiments, a thinner composite can be formed from a stacking of just a rigid layer 30, an adhesive layer 34, and a flexible layer 24/36, though this structure is not symmetrical across the layers. The rigid layers 30 are machined to have gaps that correspond to fold lines, while the flexible layer 24/ 36 is continuous, thereby providing a joint where the flexible layer 24/36 extends across the gaps machined from the rigid layers 30.

Characterization of the structure as being "super-planar" means taking multiple planar layers and selectively connecting them. An analogy here can be drawn to circuit boards, where electrical vias connect circuits on different layers. Here, in contrast, the structure is made with "mechanical vias" that form out-of- plane physical links between layers. By stacking multiple planar layers, the range of achievable devices is greatly expanded. The super-planar structure also enables features and components to be packed into the structure that would not fit if the device could only be made out of one planar sheet. Advantageously, super-planar structures with mechanisms that operate normal to the plane can now be made with these techniques. In practice, forming Sarrus linkages between planar layers is an advantageous strategy for designing an assembly mechanism/ scaffold. Other mechanisms can attach to the Sarrus links to effect the intended component rotations.

The multi-layer super-planar structure can be fabricated via the following sequence of steps, which are further described, below: (1) machining each planar layer, (2) machining or patterning adhesives, (3) stacking and laminating the layers under conditions to effect bonding, (4) post-lamination machining the multi-layer structure, (5) post-lamination treatment of the multi-layer structure, (6) freeing an assembly degree of freedom in each structure, (7) locking connections between structural members, (8) freeing any non-assembly degrees of freedom, and (9) separating finished parts from a scrap frame.

A schematic representation of the pop-up MEMS process is provided in FIG. 1, illustrating how the basic operations of micromachining 12 and 16; lamination 15; pick-and-place 14 and 18; folding 19; locking 20, and additional micromachining 21 can be performed to manufacture pop-up MEMS machines.

These assembly techniques can include the formation of folding joints, wherein (i) features are first micro-machined 12 in individual material layers, and the resulting chips are removed; (ii) during lamination, dowel pins align material layers 13 while heat and pressure are applied 15; for example, two rigid carbon-fiber layers can be bonded to a flexible polyimide-film layer with adhesive to form a five- layer laminate referred to as a "linkage sub-laminate"; (iii) micro-machining 16 cuts mechanical bridges that constrain individual elements, allowing the creation of articulated structures; and (iv) a completed folding joint is formed and removed from the surrounding scaffold 19. A castellated pattern allows the flexure joint to approximate an ideal revolute joint. All assembly folds in a more-complex assembly can be incorporated into a single "pop-up" degree of freedom, which can be locked in place by a soldering process after pop up and then released by micro-machining. Adhesion between layers is achieved by patterning adhesive 34 (see FIG. 8) onto one or both sides of a non-adhesive layer or by using free-standing adhesive layers ("bondplies"). In the latter case, the free-standing adhesive can be an intrinsically adhesive layer, e.g., in the form of a sheet of thermoplastic or thermoset film adhesive, or an adhesive laminate, such as a structural material layer with adhesive pre-bonded to one or both sides. The adhesive layer 34 is machined like the other layers. Specific examples of sheets that can be used as the adhesive layer 34 include sheet adhesives used in making flex circuits {e.g., DuPont FR1500 adhesive sheet) or polyimide film coated with FEP thermoplastic adhesive on one or both sides. Free-standing sheet adhesives can be acrylic-based for thermosets;

alternatively, the adhesive 34 can be thermoplastic, wherein the thermoplastic film can be formed of polyester, fluorinated ethylene propylene (or other fluoropolymer), polyamide, polyetheretherketone, liquid crystal polymer, thermoplastic polyimide, etc. Any of these adhesives 34 can also be applied on one or both sides to a non- adhesive carrier. In additional embodiments, a layer may serve both as a structural layer and as a thermoset adhesive; exemplary compositions for such a layer include liquid crystal polymer or thermoplastic polyimide. Furthermore, for special types of structural layers, a variety of wafer bonding techniques that do not require an adhesive 34 may be employed, such as fusion bonding.

In another technique for achieving adhesion between layers, adhesive 34 is applied and patterned directly on a non-adhesive layer, such as a rigid layer 30. This technique can be used where, for example, the type of adhesive 34 desired may not be amenable to free-standing form. Examples of such an adhesive 34 include solders, which are inherently inclined to form a very thin layer, or adhesives that are applied in liquid form (by spraying, stenciling, dipping, spin coating, etc.) and then b-stage cured and patterned. B-staged epoxy films are commonly available, but they usually cannot support themselves unless they are quite thick or reinforced with scrim.

The resulting bond can be a "tack bond," wherein the adhesive 34 is lightly cross-linked to an adjacent layer before laser micromachining with sufficient tack to hold it in place for subsequent machining and with sufficient strength to allow removal of the adhesive backing layer. The tack bonding allows for creation of an "island" of adhesive 34 in a press layup that is not part of a contiguous piece, which offers a significant increase in capability. Another reason for tacking the adhesive 34 to an adjacent structural layer is to allow for unsupported "islands" of adhesive 34 to be attached to another layer without having to establish a physical link from that desired adhesive patch 34 to the surrounding "frame" of material containing the alignment features. In one embodiment, a photoimagable liquid adhesive, such as benzocyclobutene, can be applied in a thin layer, soft baked, and then patterned using lithography, leaving a selective pattern of adhesive. Other photoimagable adhesives used in wafer bonding can also be used.

The adhesive 34 is patterned while initially tacked to its carrier film, aligned to the structural layer using pins, and then tacked to at least one adjoining layer in the layup with heat and pressure {e.g., at 200°C and 340 kPa for one hour). Alternatively, the adhesive layer 34 can be patterned by micro-machining it as a free sheet. Tack bonding can involve application of heat and pressure at a lower intensity and for less time than is required for a complete bond of the adhesive 34. In yet another embodiment, the adhesive film 34 can be tack bonded in bulk and then machined using, for example, laser skiving/ etching. Advantageously, use of this variation can be limited to contexts where the machining process does not damage the host layer. Both of these variations have been tried using DuPont FR1500 adhesive sheet and laser skiving.

To form a multi-layer laminate structure, a multitude of these layers 24, 26, 30, 24, and 36 {e.g., up to 15 layers have been demonstrated) are ultrasonically cleaned and exposed to an oxygen plasma to promote bonding and aligned in a stack by passing several vertically oriented precision dowel pins respectively through several alignment apertures in each of the layers, and by using a set of flat tooling plates with matching relief holes for the alignment pins. In other embodiments, other alignment techniques {e.g., optical alignment) can be used. All layers can be aligned and laminated together.

Linkages in the laminated layers can be planar (where all joint axes are parallel); or the joint axes can be non-parallel, allowing for non-planar linkages, such as spherical joints. The choice of the flexible layers 24/ 36, which can be formed of a polymer— polyimide in this example— is based upon compatibility with the matrix resin in the carbon fiber. The cure cycle can reach a maximum temperature of 177°C using a curing profile of four hours. Polyimide film (available, e.g., as KAPTON film from E.I. du Pont de Nemours and Company), for example, has a sufficiently high service temperature (up to 400°C) to survive the curing step. The polyimide (or other flexible polymer) film can have a thickness of, e.g., 7.5 μηι.

The rigid layers 30 in this embodiment are standard-cured carbon-fiber sheets {e.g., with three layers of unidirectional fibers, wherein the fiber layers are oriented at 0°, 90°, and 0° to provide thickness in two orthogonal directions) having a thickness of, e.g., 100 μηι. Fifteen layers are used because the adhesive sheet 34 {e.g., in the form of a B-staged acrylic sheet adhesive, commercially available, e.g., as DuPont PYRALUX FR1500 acrylic sheets) in this embodiment is separate from each layer of structural material in the layup of this embodiment. Accordingly, the adhesive sheet 34 can be laser machined into a pattern differing from any structural layer, and aligned layups of many layers can be made. This capability enables the fabrication of parts with many linkage layers that are perfectly or near-perfectly aligned.

After the layers are stacked to form the layup, pressure and heat are applied, typically in a heated platen press to cure/ crosslink the adhesive layers 34.

Specifically, the layup can be cured in a heated press, autoclave, or other device that provides the atmosphere (or lack thereof), temperature, and pressure to achieve the bonding conditions required by the adhesive. One embodiment of the curing process uses 50-200 pounds-per-square-inch (psi) clamping pressure, 350°F (177°C) temperature, and two-hours cure time (optionally with temperature ramping control) to cure DuPont PYRALUX FR1500 acrylic sheets in a heated press with temperature, pressure, and atmosphere control.

Though a single-step lamination process has been demonstrated, a process with two sequential lamination steps may be preferred in various embodiments because it provides a third technique for altering layering composition and because it may ease the problem of chip removal. A separate printed-circuit micro- electromechanical-system (PC-MEMS) structure called a "midplate" can be included to alter the layer stack underneath a lead-zirconate-titanate (PZT) piezoelectric plate during initial lamination and then removed, allowing precise accounting for the thickness of the piezoelectric plate. The midplate can be in the form of a simple, reusable PC-MEMS laminate of a flat carbon-fiber plate containing alignment holes and a central polyimide boss designed to support the lower PZT plate. This initial lamination results in two sub-laminates, each with a layered structure including a sequence of carbon, adhesive, polyimide, adhesive, and carbon. The midplate replaces adhesive layer on top of the lower sub-laminate. The upper sub-laminate also includes the two PZT plates.

An adhesive layer 34 is tacked to the lower sub-laminate and micro-machined, while the upper sub-laminate is micro-machined to sever mechanical bridges on the central carbon spacer layer. After chips are removed from the central carbon spacer layer, these two sub-laminates are stacked and laminated together to produce the laminate structure.

The corresponding single-step process utilizes discrete shims underneath the lower PZT plate for support. Additionally, machining steps often create unwanted material regions, or "chips," which are physically removed. When the spacer layer is micro-machined after initial lamination, all chips from micro-machining can easily be removed from the exposed surface. Post-lamination machining in a single-step process results in trapped chips that must be highly engineered to enable physical removal from the internal spacer layer.

Balloon-Actuated Laminated Mechanisms

The layering and lamination steps shown in FIG. 1 can be used to fabricate flexible and/ or stretchable hermetically sealed balloon structures that define interconnected inflatable chambers 28 {i.e., with fluid communication between chambers 22 provided by linking conduits) within the pop-up MEMS laminate; and the above-disclosed materials {e.g., for rigid parts 30, flexible layers 24, and adhesives 34) can be used for the balloon structures 26 described herein. By selectively patterning the appropriate structural {e.g., polyimide or polyester) and connective {e.g., b-staged sheet adhesive) layers, hermetic chambers 28 can be formed within the laminate 22, and these chambers 28 can be selectively bonded to other components of the laminate 22. After the release of the laminate assembly from its supporting structures, inflating the chambers 28 with a gas or liquid fluid can produce useful motion in the pop-up MEMS device. This actuation method may be particularly useful in medical applications where other types of actuators may be undesirable due to toxicity of constituent materials, such as lead zirconate titanate (PZT).

In particular embodiments, the laminate structure 22 can also include spring returns attached to the balloon structures 26 or to structural components {e.g., rigid parts 30) attached to the balloon structures 26 to return the mechanism to its original configuration after actuation. In these embodiments, the springs can be put in, e.g., tension or compression when the chambers 28 are actuated by

pressurization; and when that pressure is removed, the tension/ compression in the springs can be released and the resulting expansion or compression of the spring can push or pull the mechanism back to its original configuration.

Laminated balloon actuators in the context of pop-up MEMS represent a very large design space; here, we describe several representative examples. FIGS. 2 and 3 show steps in the fabrication process and the resulting device for a simple

embodiment of a balloon actuator that includes several balloon pouches 26 connected in series. In the embodiment of FIG. 2, the interconnected actuator pouches 26 are formed of two flexible layers 24 in the form of 25-micron-thick polyimide film {e.g., KAPTON film from DuPont), wherein each balloon pouch 26 is 2.5 x 4.0 mm in length and width; and those flexible layers 24 are subjected to a weight stack press cure cycle. When pressurized (here, using an air-filled syringe, as shown in FIG. 4), the resulting balloon pouches 26 inflate, while the overall length of the chain is reduced, similar to a McKibben actuator, as shown by the sectional illustrations of the depressurized and pressurized actuators, shown respectively in FIGS. 5 and 6.

As shown in FIGS. 5 and 6, the balloon actuator 26 exerts force primarily when contracting. When depressurized, the balloon actuator 26 will generally return to its original length but will not exert significant force on a load in the process. A laminate structure 22 in the form of an electrode paddle designed to be inserted percutaneously into the spine for pain management is shown in FIGS. 7 and 8. As shown in the exploded view of FIG. 8, the laminate structure 22 of the electrode paddle comprises (from the top of the drawing) flexible balloon polyimide layers 24 {e.g., KAPTON polyimide film from DuPont); an adhesive trace 34 (formed of, e.g., PYRALUX B-staged modified acrylic adhesive from DuPont) that joins the flexible balloon layers 24 via a thin perimeter band {e.g., extending from the edge of the flexible balloon layers 24 with a width of ~1 mm or less), leaving the central region between the flexible layers 24 unbonded; the second flexible balloon polyimide layer 24; balloon adhesive patch layers 34, an insulating substrate sheet 30 formed, e.g., of steel; another adhesive layer 34 (formed, e.g., of the PYRALUX adhesive); a flexible electrically conductive layer 36 [formed, e.g., of KAPTON polyimide layer with electrically conductive traces (formed, e.g., of copper) printed thereon or of FR4 fiberglass (woven fiberglass cloth with an epoxy resin binder)] that operates as a hinge; another adhesive layer 34 (formed, e.g., of the PYRALUX adhesive); and a top rigid layer 30 {e.g., formed of steel) at the bottom of the drawng. The paddle is inserted through a needle {e.g., through the skin and into the body) in a folded configuration. After the paddle exits the needle, pumping fluid {e.g., air or liquid) into the integrated balloon actuators forces the paddle into an unfolded, flat configuration designed to rest over the spinal cord.

The structure of an exemplary pop-up MEMS device 22 and integrated balloons 26, including all constituent layers, is shown via a top-side view (at the top) in FIG. 7, via a bottom-side view with the balloons 26 deflated (in the middle image), and via a bottom-side view with the balloons 26 inflated (in the bottom image). The sectional views of FIGS. 9-11 illustrate the operating principle of the balloon actuators 26, wherein the depressurized balloons 26 are shown in FIG. 9. The hinge structure 22 begins to open as the chambers 28 defined by the balloons 26 are partially pressurized {e.g., via a pump), as shown in FIG. 10. When the balloons 26 are fully pressurized, the hinge is fully opened, as shown in FIG. 11. The unfolding process is unidirectional; and a separate, external device {e.g., a constricted channel through which the panel can be pulled through) can be used to collapse the paddle 22 back into the folded position for removal or repositioning.

Finally, FIGS. 12 and 13 show the operating principle of an integrated balloon actuator 26 bonded to two rigid pop-up MEMS parts 30 connected by an inextensible flexural layer 36 (a standard feature of popup MEMS). When the balloon 26 is inflated, as shown in FIG. 13, the two rigid parts 30 are forced apart by the balloon actuator 26 but constrained by the inextensible flexural layer 36. In this case, depressurizing the balloon 26 brings the rigid parts 30 back together, as shown in FIG. 12, enabling bidirectional actuation. In FIG. 13, the maximum angle between the surfaces of the rigid parts 30 is limited by the conformational change of the balloon 26. If several balloons 26 are attached in series between the two rigid parts 30, the angle can be 180 degrees or more.

The configurations described above represent a limited subset of the potential embodiments of this technology. Relevant design choices include the following:

1) the balloon actuator 26 may be composed of flexible materials that can either be extensible or inextensible;

2) the balloon actuator 26 may be inflated either pneumatically or

hydraulically;

3) the balloon actuator 26 may work unidirectionally {e.g., inflation causes a device 22 to unfold, but a separate restoring force is used to close it) or bidirectionally {e.g., increasing the pressure in the balloon 26 causes the device 22 to unfold, while lowering the pressure in the balloon 26 causes the device 22 to fold);

4) the balloon actuator 26 can be structured as a single large chamber or as a network of smaller connected chambers; actuator geometry is highly specific to the structure and desired kinematics of a particular pop-up MEMS device;

5) the balloon 26 can be attached to an exterior or interior surface of the popup MEMS device, or it can fully enclose the pop-up MEMS device and, itself, function as the exterior surface; 6) the balloon 26 may be filled with a substance that solidifies {e.g., due to a change in temperature, humidity level, or pH, or due to exposure to UV light, or with time), locking the pop-up MEMS device in a desired configuration; this change may or may not be reversible.

Additional examples consistent with the present teachings are set out in the following numbered clauses:

1. A method of incorporating balloon actuators into a laminated mechanism, comprising:

bonding patterned flexible layers with an adhesive trace to form at least one balloon with a central unbonded region that forms a hermetic chamber; and

bonding at least one of the patterned flexible layers selectively to more- rigid parts of the laminated mechanism in a configuration such that pressurization of the hermetic chamber(s) produces relative linear or rotational displacement of at least one of the more-rigid parts with respect to another of the more-rigid parts.

2. The method of clause 1, wherein the at least one balloon comprises a plurality of interconnected balloons, wherein the hermetic chambers defined by the balloons are joined by passages for fluid communication therebetween.

3. The method of clause 2, wherein the hermetic chambers are joined in series.

4. The method of any of clauses 1-3, wherein the laminated mechanisms further comprises an additional flexible layer bonded to the more-rigid parts.

5. The method of any of clauses 1-4, wherein the patterned flexible layers are bonded with an adhesive trace.

6. The method of clause 4 or 5, wherein the laminated mechanism further

comprises an additional adhesive layer that bonds the additional flexible layer to the more-rigid parts.

7. The method of any of clauses 4-6, wherein the additional flexible layer is

substantially inextensible such that the more-rigid parts (a) unfold when the hermetic chamber(s) is/ are pressurized and (b) return to a folded state when the hermetic chamber(s) is/ are depressurized. 8. The method of any of clauses 1-7, wherein the more-rigid parts and the balloon(s) form a hinge, and wherein pressurization of the hermetic

chamber(s) causes the hinge to pivot open.

9. The method of clause 8, wherein the balloon(s) is/ are folded and stacked

between the more-rigid parts in a laminated structure when the balloon(s) is/ are unpressurized.

10. The method of any of clauses 1-9, wherein pressurization of the hermetic

chamber(s) produces an increase in length of the laminated mechanism.

11. The method of any of clauses 1-10, wherein the patterned flexible layers that form the balloon comprise a polyimide.

12. A balloon actuated laminate mechanism, comprising:

at least two patterned flexible layers bonded along their edges with a central unbounded region that forms a hermetic chamber; and

rigid parts that are more rigid than the patterned flexible layers in a configuration such that pressurization of the hermetic chamber(s) produces relative linear or rotational displacement of at least one of the rigid parts with respect to another of the rigid parts.

13. A method of balloon actuating a laminate mechanism, comprising:

providing a laminate mechanism comprising a balloon actuator including at least two patterned flexible layers bonded along their edges with a central unbounded region that forms a hermetic chamber; and rigid parts that are more rigid than the patterned flexible layers; and

pumping fluid into or out of the hermetic chamber of the balloon actuator to inflate or deflate the balloon, wherein the inflation or deflation of the balloon produces relative linear or rotational displacement of at least one of the rigid parts with respect to another of the rigid parts.

In describing embodiments of the invention, specific terminology is used for the sake of clarity. For the purpose of description, specific terms are intended to include at least technical and functional equivalents that operate in a similar manner to accomplish a similar result. Additionally, in some instances where a particular embodiment of the invention includes a plurality of system elements or method steps, those elements or steps may be replaced with a single element or step.

Likewise, a single element or step may be replaced with a plurality of elements or steps that serve the same purpose. Further, where parameters for various properties or other values are specified herein for embodiments of the invention, those parameters or values can be adjusted up or down by l/100 ^th , l/50 ^th , l/20 ^th , l/10 ^th , l/5 ^th , l/3 ^rd , 1/2, 2/3 ^rd , 3/4 ^th , 4/5 ^th , 9/10 ^th , 19/20 ^th , 49/50 ^th , 99/100 ^th , etc. (or up by a factor of 1, 2, 3, 4, 5, 6, 8, 10, 20, 50, 100, etc.), or by rounded-off approximations thereof, unless otherwise specified. Moreover, while this invention has been shown and described with references to particular embodiments thereof, those skilled in the art will understand that various substitutions and alterations in form and details may be made therein without departing from the scope of the invention. Further still, other aspects, functions, and advantages are also within the scope of the invention; and all embodiments of the invention need not necessarily achieve all of the advantages or possess all of the characteristics described above. Additionally, steps, elements and features discussed herein in connection with one embodiment can likewise be used in conjunction with other embodiments. The contents of references, including reference texts, journal articles, patents, patent applications, etc., cited throughout the text are hereby incorporated by reference in their entirety; and appropriate components, steps, and characterizations from these references may or may not be included in embodiments of this invention. Still further, the components and steps identified in the Background section are integral to this disclosure and can be used in conjunction with or substituted for components and steps described elsewhere in the disclosure within the scope of the invention. In method claims (or where methods are elsewhere recited), where stages are recited in a particular order— with or without sequenced prefacing characters added for ease of reference— the stages are not to be interpreted as being temporally limited to the order in which they are recited unless otherwise specified or implied by the terms and phrasing.