Bio‐Inspired Dynamically Morphing Microelectronics toward High‐Density Energy Applications and Intelligent Biomedical Implants

Choreographing the adaptive shapes of patterned surfaces to exhibit designable mechanical interactions with their environment remains an intricate challenge. Here, a novel category of strain‐engineered dynamic‐shape materials, empowering diverse multi‐dimensional shape modulations that are combined to form fine‐grained adaptive microarchitectures is introduced. Using micro‐origami tessellation technology, heterogeneous materials are provided with strategic creases featuring stimuli‐responsive micro‐hinges that morph precisely upon chemical and electrical cues. Freestanding multifaceted foldable packages, auxetic mesosurfaces, and morphable cages are three of the forms demonstrated herein of these complex 4‐dimensional (4D) metamaterials. These systems are integrated in dual proof‐of‐concept bioelectronic demonstrations: a soft foldable supercapacitor enhancing its power density (≈108 mW cm−2), and a bio‐adaptive device with a dynamic shape that may enable novel smart‐implant technologies. This work demonstrates that intelligent material systems are now ready to support ultra‐flexible 4D microelectronics, which can impart autonomy to devices culminating in the tangible realization of microelectronic morphogenesis.


Introduction
Biological systems autonomously structure and craft their distinctive physical configurations.Living multicellular organisms utilize 3-dimensional (3D) cellular microstructures to form and delimit their body shape, as well as to guide their self-maintenance, regulating nutrient transport and growth, as well as the changes of shape required for self-reproduction.This basic phenomenon of 3D structure formation, termed morphogenesis, encompasses structural composition and organizational intricacies as well as the overall form and is for living organisms the product of natural selection. [1]Natural morphogenesis is governed by a spectrum of genetic and environmental factors, influencing cell proliferation and death as well as the mechanical behaviors of cells including self-assembly and tissue folding, and guiding the establishment of tissues, organs, and the overarching anatomy of organisms. [2]6] Such systems typically require advanced robotics and sophisticated instrumentation which harness a fusion of mechanical, chemical, and electronic interactions. [7,8][17] These components exhibit diverse functionalities, including purposeful reshaping, [18] gripping actions, [19] pattern alternations, [17] tissue envelopment, [20] and locomotion. [21]The driving forces behind these transformations may include manifold interactions modulated by light, [22] electric current, [23] temperature changes, [17] or magnetic fields. [11][26] By utilizing origami-inspired assembly through electrochemically driven redox reactions, a collection of 3D structures has been successfully generated, opening up possibilities for microscale 3D shapememory actuators. [27]Furthermore, by integrating 3D sensors into electronic skin with embedded artificial hairs, a flexible approach for producing active-matrix integrated sensor arrays has been devised, providing critical insights toward the realization of real-time tactile perception in multiple directions. [28]Evidently, the fusion of digital information processing capabilities with these materials systems further enables the spatial and dynamic (viz.4D, short for 4-dimensional) control of electronic device morphability. [6]34] The convergence of electronic information-driven shapechanges (viz.artificial morphogenesis) holds the potential to usher in a new era of synthetic organisms. [35]These entities will embody the information-controlled sustainable traits observed in the natural world capturing the core properties of living organisms. [36]Nevertheless, these techniques face strong constraints when it comes to generating high-performance morphable heterostructures, mainly due to their rigidity and the challenges they pose in flexible shape formation and microelectronics integration.This becomes particularly evident in their inability to seamlessly craft intricate structures like multifaceted mesosurfaces (Figure 1a.1), reversibly morphable cages (Figure 1a.2), and adaptive auxetic tessellations (Figure 1a.3)structures important for enriching artificial organs or intelligent implants with sensing, [37,38] energy storage, [39,40] and communication capabilities. [8,41]Thereby we benefited from thin-film microelectronics and contemporary mass manufacturing processes to deterministically generate micro-origami tessellation assemblies and construct actively morphable 3D electronics.This emergent strategy hinges on shapeable material technologies, [14,42] facilitating the creation of 3D self-assembled components and systems that have already been guided by external stimuli. [43,44]e driving force for swelling and shrinking stimuliresponsive actuators is the uptake and release of molecules in response to physical cues like temperature fluctuation, [17] ionic strength, [45] light irradiation, [22] pH variation, [39] and electrochemical reactions. [30][48] In particular, the integration with microelectronics is prone to culminate in the mass fabrication of 4D heterostructures with electronically-driven morphability -an achievable goal, as this article demonstrates, and one that is broadly appealing for reaching the power-density and ultra-flexibility features required by modern 4D autonomous bioelectronics. [49,50]otential uses for biocompatible electronically morphing sheets encompass the improvement of intelligent biomedical technologies to enable minimally invasive procedures and wireless health monitoring right after device implantation. [51,52]Likely trials include the development of aneurysm embolization smart tissues (Figure 1a.4), intelligent stents for airways and arteries (Figure 1a.5,a.6,respectively), and nerve-regeneration smart scaffolds (Figure 1a.7).These innovations may bring remarkable advances in the field of medical science. [52]Notably, the electronically morphable implants mean to be capable of adapting to the biological shape of the target tissue wirelessly, providing controlled and assisted clot formation to carry on biological healing. [52]Utilizing integrated sensors, actuators, and microantennas, the 4D smart implants mean to monitor the patient's condition after every medical intervention. [37]This will enable medical professionals to detect inflammation or recurring issues even before new symptoms appear.With this technology, medical intervention can be even more effective and efficient in promoting healing, recovery, and overall well-being -providing hope for a better future.
Here, we leverage the prominent advancements in smart materials to create new bio-inspired 4D multifunctional applications.Our approach employs a broad range of materials, including stimuli-responsive hydrogels (HGs), thin films, nanomembranes, flexible substrates, organic mixed ionic-electronic conductors, and electroactive artificial muscles.The distinctive result is the creation of multifaceted morphable metamaterials that serve as actively foldable 4D hosts for microelectronics, just termed here as morphogentronics (Figure 1b).In our scheme, the stimuli-responsive films are patterned and then applied as chemo-and electromechanical actuator hinges of micro-origami tessellations.This method employs 4D fabrication means that start with the integration of photo-patterned structures with a robust foldable host tessellation through standard lithography (Figure 1b.1).The patterning of actuators at the polyimide (PI) flexible substrate (FS) joints allows for hosting electronics in dedicated regions (Figure 1b.2).Following such integration of thinfilm microelectronics the next step is controlled delamination of the host tessellation.Figure 1b.3 illustrates the active mountainand valley hinges (MH and VH, respectively) that can assemble upon external stimuli after delamination.The combination of multiple zig-zag units into a single tessellation (as shown in Figure 1b.4),along with the precise multidimensional control provided by the micro-origami actuator hinges (as illustrated in Figure 1b.5), can enable electronics to undergo complex shape transformations actively.This bears a resemblance to natural 2), and auxetic shell (a.3).Technological advances in this field may benefit energy-and power density, electronic component density, and electronic information processability.Envisioned dynamically morphing devices may be deployed to aid in the rehabilitation and ongoing monitoring of various medical conditions including embolized aneurysms (a.4), endobronchial diseases (a.5), atherosclerosis (a.6), and peripheral nerve injuries (a.7).b) Morphogentronics approach proposed for the creation of dynamically morphing micro-origami tessellations: actuator hinge patterning on flexible joints and substrates (b.1), providing functional space for flexible electronics counterpart integration (b.2), and giving rise to actuator-hinge foldable device units (b.3).The monolithic integration and 4D fabrication enable the manufacture of several subsequent foldable units into the multifaceted tessellation (b.4), giving rise to complex 4D microelectronic tissues (b.5).morphogenesis, which is discussed in detail hereafter.Compared to previously reported structures, [46,47,[53][54][55] our achievements systematize the 4D fabrication of stimuli-responsive microscale multifaceted folded packages, auxetic multi-stable surfaces, and auxetic cages.We succeed in realizing multidimensional control of chemically-and electronically-morphing microstructures where the number of active hinges is significantly higher than the number of faces.Furthermore, our findings show that the micro-origami tessellations' strategic creases can be equipped with: 1) miniaturized energy conversion and storage units to deliver outstanding power density (up to 108 mW cm −2 ) and power the so-called smart-dust technologies, [56] and 2) electroac-tive polymer actuator micro-hinges to mimic morphogenesis in an electronic-information-driven fashion that appeals to the field of intelligent biomedical implants. [52]These achievements showcase the adaptability and scalability of morphogentronics toward ultra-flexible, 4D, and autonomous electronics.

Results and Discussion
The versatility of the chemo-mechanical actuator hinge approach is remarkable and enables the successful assembly of intricate 4D micro-origami tessellations from their planar, photo-patterned counterparts.The active-hinge structure configuration of each tessellation employed here is delineated in Figure 2a, featuring the (a.1)Miura-Ori, (a.2) sharp-angle Miura-Ori, (a.3) Reschtriangle, and (a.4) waterbomb crease patterns.Notably, the HG MHs and VHs are visually indicated by solid-red and solid-blue lines, respectively.For a more detailed view of the intricate intercalation between MHs and VHs along each origami's flat-sheet structure, zoomed-in ovals are also presented in Figure 2a.Subse-quently, Figure 2b depicts the corresponding micro-origami tessellations.The tessellation fabrication procedures are provided in the Experimental Section.Notably, the crease pattern schematic in Figure 2a.1 is similar to the developable micro-origami tessellation introduced in Figure 1b.For a complementary analysis of the Miura-Ori sample, its photo-patterned HG-hinge micro-origami tessellation is shown in Figure S1 (Supporting Information), whereas the additional details about multi-material stack, FS releasing, and 3D self-assembly are presented in Note S1 (Supporting Information).
Following the selective dissolution of the sacrificial layers (SLs) and the release of all micro-origami tessellations from their glass slides, these freestanding materials were immersed in distinct solutions, differing in pH to evaluate and calibrate the chemo-mechanical actuation facilitated by the pH-responsive HG-hinges.The microscopy images in Figure 2c.1-c.4 captured the results of the immersion processes for the four different micro-origami tessellations.Figure S2a.1 (Supporting Information) exhibits the variation in the tessellation's folding level (FL) after alternating immersion in various solutions, cycling pH.Moving from left to right in Figure 2c.1-c.4,the pH levels increase from 3 to 9, correlating with incremental changes in the FLs.The generation of complex 4D shapes is achieved through two distinct means: by modifying the HG-hinge actuator geometry (from the top in c.1 to the bottom in c.4) or by adjusting the pH levels (from left to right).Figure 2d.1-d.4 presents the corresponding maximum-strain distributions calculated along the mostly folded tessellations at steady-state using the Origami Simulator application. [57]The folding dynamics of the HG-hinge micro-origami tessellations are discussed in Supporting Information (Note S2, Supporting Information).In the case of the Miura micro-origami tessellation (Figure 2d.1), we observed a remarkable ≈90% FL accompanied by a 0.10% maximum strain on the rigid facets at pH = 9.The micro-origami tessellation featuring the sharp-angle Miura-Ori geometry (Figure 2d.2) achieved a comparable FL of ≈93% with a maximum strain of only ≈0.01% at the same pH level.Conversely, the Resch-triangle microorigami tessellation (Figure 2d.3) encountered a few limitations, reaching a steady state at ≈72% FL.Notably, the strain transferred to the tessellation's rigid facets reached ≈1.02%.The waterbomb micro-origami tessellation, as depicted in Figure 2d.4,achieved FL ≈ 74% with a maximum strain of ≈0.48% at pH = 9.The tessellation response at pH > 9 is shown in Figure S2a.2 (Supporting Information), whereas the optical microscopy images acquired for Miura-Ori degradation at this alkaline condition are exhibited in Figure S2b (Supporting Information) and discussed in Note S3 (Supporting Information).
To assess quantitatively the chemo-mechanical response of HG hinges, Figure 2e exhibits FL and maximum strain, as well as their interdependence on pH.For simplicity, Figure 2e shows the single-sweep data analyses.The corresponding dual-sweep data are provided in Figure S3 (Supporting Information).The dotted boxes in Figure 2e.1 correspond to the experimental data that align with the strain distribution plots in Figure 2d, while dashed lines serve as visual guides for each sample geometry.In terms of FL, the Miura-like geometries consistently outperformed the others across the entire pH range.Notably, the Sharp-angle Miura tessellation exhibited superior folding performance, achieving FL = 80% at pH = 5 and smoothly increasing to FL = 93% at pH = 9.This gradual behavior was attributed to the well-defined 3D geometry adopted by the Sharpangle Miura tessellation within the pH range of 5 to 9, as evidenced in Figure 2c.2.A comparable trend was observed for the Resch-triangle micro-origami tessellation, with FL increasing smoothly at pH > 4 (Figure 2e.1), owing to its stable quasicylindrical geometry (Figure 2c.3).Turning to Figure 2e.2, which illustrates the maximum strain as a function of FL, the deformations transferred from the HG hinges to the tessellation facets exhibited a tight dependence on the micro-origami geometry.Interestingly, the maximum rigid-facet deformation did not align with the maximum FL.The consistent characteristic among the curves in Figure 2e.2 was the attainment of peak deformation within the FL range of 45% to 70%.For a more precise analysis of pH's role in the deformation of each micro-origami tessellation, FL was correlated with pH based on the data from Figure 2e.1,e.2.Subsequently, Figure 2e.3 presents the maximum strain as a function of pH.Here, we observed that the Miura tessellation has achieved maximum deformation (≈2% maximum strain) at pH = 4.The Sharp-angle Miura sample exhibited a similar trend, albeit with a ≈0.09% maximum strain at pH = 3.In contrast, both the Reschtriangle and waterbomb tessellations displayed ≈1% maximum strain at pH = 7, despite their inherently distinct deformation profiles.A complementary analysis considering both the FL and maximum-strain dual-sweep data is provided in Note S4 (Supporting Information).
The new level of active origami scalability provided by our approach offers a qualitative jump in the realization of soft metamorphous micro-objects, sufficient to provide novel functions from enhanced energy storage and power densities, multiplexed sensor density, mechanical actuation capacity, and microrobotic integration levels.To demonstrate this, we present an energy/power-management concept made possible unequivocally by the dynamically morphing origami tessellations.Drawing inspiration from natural morphing systems like the leaf of the hornbeam Carpinus betulus, [58] found in nature as a tiny compact package (Figure 3a Figure 3c.1 exhibits the bio-inspired tessellation on a glass slide along with the superposition of its folded package, evidencing the footprint area reduction above 90%.The bio-inspired device tessellation is released from the glass slide through the selective removal of the SL, resulting in the formation of the bio-inspired morphogenetic CCs as depicted in Figure S4 (Supporting Information).In Figure 3d, we present the morphogenetic supercapacitor with a profound bio-inspired design.The mass-transportation path throughout the electrolyte is illustrated by the white lines connecting CC + and CC − (Figure 3d), whereas its inset provides a detailed view of the positive and negative supercapacitor plates along with the schematics for the mass-transportation path.The microscopy images of the collector wires at various actuation states are shown in Figure S5 (Supporting Information), whereas the electric-field distribution calculated at the supercapacitor plates is provided in Figure S6 (Supporting Information) for FL = 0, 20%, and 55%. Figure S6 (Supporting Information) also shows the electrochemical examination of the morphogenetic device platform after actuation in various pH solutions.
Figure 4a exhibits the cyclic voltammetry characterization realized for the 55% FL, 20% FL, and the non-released supercapacitor.The optical microscopy images of each shape conformation are shown in Figure 4a.2-a.4.The voltammogram characteristics in Figure 4a.1 demonstrate that devices display capacitive behavior arising from electrochemical double-layer formation. [59]mong the electrochemical characteristics are the absence of charge-transfer reactions, [60] and the curved shapes that resemble parallelograms as evidenced by the remarkable hysteresis loops without peak current signatures. [40]The increased current is due to the increased electrochemically active area of the morphogenetic devices as provided by the additional b-CC in the released states.The apparent elongation displayed by the increasing-FL curves compared to the non-released one is ascribed to the shorter ion drift path provided by the micro-origami folding that also leads to lower solution resistance (R e ).To assess the validity of this hypothesis, we performed electrochemical impedance spectroscopy (EIS).The EIS capacitance-resistance curves are exhibited in Figure 4b for the (b.1) 55% FL, (b.2) 20% FL, and (b.3) non-released devices as a function of the electric field frequency.The complex impedance data are plotted in Figure S7 (Supporting Information).We found that R e decreases from ≈200 to ≈60 Ω upon FL increment from 20% to 55%, confirming our hypothesis.We measured ≈180 μF for the capacitance of the folded supercapacitors at 0.25 Hz (Figure 4b.1,b.2),whereas the non-released device displayed a ≈60 μF capacitance at the same frequency.Notably, the capacitance did not change upon either FL = 20% or 55%.We also assessed the device's FL-dependent cycle stability by successive galvanostatic chargedischarge acquired at different folding configurations for 30 s (Figure 4c.1-c.3) and 40 cycles (Figure S8, Supporting Information).The EIS and cycle stability evaluation have thus corroborated that an increasing FL impacts directly on the R e lowering, whereas electrochemical double-layer formation is barely affected by the different 3D conformations of the device.Additional considerations regarding the supercapacitor measurement conditions are provided in Note S5 and Note S6 (Supporting Information).
high-end scarce metal ion supercapacitors like Ru 2+ .Figure 4d.2 shows that the PEDOT morphogenetic supercapacitor at 90% FL achieves a comparable energy density (viz.3 μWh cm −2 ) and areal capacitance considerably higher (viz.90 mF cm −2 ) than most state-of-the-art supercapacitors.The morphogenetic supercapacitors also reached an FL-dependent power density ranging from ≈14 to ≈108 mW cm −2 upon FL increasing from 20 to 55%.These values figure among the state-of-the-art hall of power density for symmetric supercapacitor systems (viz.≈100 mW cm −2 ). [40]he advantages of morphogentronics are not restricted to static properties of folded structures but increase further when the devices can take control over their folding during deployment.We introduce the hybrid-hinge approach by integrating HG and polypyrrole (PPy) actuators to form a multi-stimuli responsive grid of hinges, as shown in Figure 5.As we now demonstrate, this approach offers precise and independent control over assembly, deployment, and actuation, especially for biomedical device smart technologies such as intelligent implants.Figure 5a exhibits the as-fabricated dynamic shape implant prototype at different pH levels.The prototype is based on the waterbomb microorigami tessellation, which may self-assemble from a wrinkled mesosurface (pH = 2) to curved shells (pH = 4) to auxetic cages (pH = 6), and vice versa, through chemical pre-programming.Figure 5b.1 shows the prototype resting on a forefinger tip, whereas a detailed zoom-in image of the prototype cage is provided in Figure 5b.2.Further considerations about the material's biocompatibility are provided in the Experimental Section along with the PPy-actuator's working principle and fabrication details.The hybrid-hinge stacking structure is provided in Figure S9 (Supporting Information), whereas details about the PPy thin-film actuation are available in Figure S10 and Video S1 (Supporting Information).
Figure 5c presents optical microscopy images acquired during the fabrication of the dynamic-shape implant prototype.In Figure 5c.1, one can see the hybrid-hinge grid, and Figure S11a,b (Supporting Information) displays the complete sample.For a closer examination of the hinge arrangement, refer to the zoomed-in image in Figure 5c.2.Notably, to achieve the suitable folding of the initial cylindrical shell, we employed HG actuators in the "×"-type hinges of the waterbomb crease (Figure 5c.2).They are spatially isolated from the "+"-type hinges, which are based on PPy and intended to provide pH-independent electronic control of deployment and actuation.In this configuration, the PI substrate serves as a passive support for the PPy actuator.To optimize the curvature of the electromechanical hinge relative to the thickness of the PI FS (t PI ), we employed the simple relationship derived from previous literature, [76] where PPy thickness (t PPy ) is estimated as t PPy = 3.6 × t PI + 0.2 μm. [20]Additional details are provided in the Experimental Section and Figure S9 (Supporting Information).
The tessellation's release from the glass slide is performed as described in the Experimental Section.The prototype assembly is performed in a 0.1 m sodium dodecyl benzene sulfonate (NaDBS) solution, as shown in Figure 5d.1-d.3 for increasing assembly time.Figure 5d.4 illustrates the time evolution of FL measured during the assembly of the implant prototype.In contrast to the HG-hinge tessellation, which reached a stable 25-30% FL after stabilization in the pH range of 5 to 6 (Figure 2e.1), the hybrid hinge system demonstrated the ability to maintain a maximum FL of (18 ± 4)% (Figure 5d.4).This is because the hybrid system allocates only ≈44% of its hinges to HG actuators, while the remaining ≈56% are dedicated to PPy actuators.After a 4-minute assembly, as depicted in Figure 5d.5, the waterbomb tessellation unit cell (front view) closely resembles the shape of the nonreleased sample (Figure 5c.2).However, in Figure 5d.6, which shows the same unit cell front view after 40 min of assembly, the triangular faces begin to deviate from their initial coplanar configuration.The yellowish bright spots in the images result from light scattering by the gold (Au) surfaces (only visible from the front of the samples) and indicate that the waterbomb cell in Figure 5d.3 resembles a mountain-like structure defined by the "×"-type HG hinges.Our work with this assembly underscores the robustness of using chemical actuators to ensure consistent foldability in flexible microdevices.Even with a reduced number of chemically active hinges, by ≈56%, the envisioned shapes can still be achieved successfully at moderate pH levels.
Figure 5e illustrates the precise electrochemical shape control facilitated by the hybrid-hinge approach.Various shape conformations achieved during the actuation cycle are displayed in Figure 5e.1-e.5.The FL time-evolution of the tessellation in response to the applied electrical stimuli is presented in Figure 5e.6 (main y-axis), with the applied electrical stimuli shown on the secondary y-axis.The full actuation cycle is available in Video S2 (Supporting Information).Figure 5e.7 displays the compact waterbomb cell after the 80 min folding (FL ≈ 67%), whereas the unfolded waterbomb cell is shown in Figure 5e.8 after the electromechanical folding cycle, with FL ≈ 20%.The pulse-train stimuli applied to the PPy hinges are depicted in Figure S12 (Supporting Information) along with the PPy current acquired during the actuation cycle.These results demonstrate the versatility of hybrid-hinge 4D fabrication, providing access to various dynamic shapes and possibilities for integrating electronic functionalities.
Electronically morphable biotechnologies have the potential to revolutionize the field of intelligent biomedical devices by providing minimally invasive alternatives to common medical procedures.Early potential application niches include the development of adaptive smart tissues for aneurysm embolization, [77] intelligent stents for airways and arteries, [52,78] and compliant smart scaffolds for nerve regeneration, [79] as illustrated previously in Figure 1a.4-a.7.A microcatheter can be used to implant the electronically morphable tissues in specific locations in the human body.The implants would then adapt wirelessly to the biological shape of the target, whether it be the volume of the aneurysm, the inside diameter of the airway or artery, or the nerve surface.Considering aneurism embolization, these morphable implants may replace the usual endovascular coiling, which still presents risks of blood clotting, bleeding, hematoma, rupture, and recurrence of the aneurysm. [80,81]For vascular stenosis and tracheal diseases, [82] the electronically morphable tissues are expected to offer exceptional control over the implant shrinkage ratios.In all cases, such smarter implants would promote controlled clot formation and assist in monitoring the patient's condition after every medical intervention, providing information about biological healing.They would also inform doctors or patients of the possible occurrence of inflammation or recurring issues, even before new symptoms appear.The utilization of electronically morphable smart devices as operative tools or implants may thus beneficially impact various medical procedures including patient rehabilitation.

Conclusion
The morphogentronics concept was demonstrated for 4 distinct micro-origami tessellation architectures, namely the Miura-Ori, the sharp-angle Miura-Ori, the Resch triangle tessellation, and the waterbomb tessellation (Figure 2a,b).Thereby we extended our investigations to create freestanding multifaceted folded packages, auxetic multi-stable surfaces, and auxetic cages, all chemo-mechanically characterized (Figure 2c,d).These advances offer fresh possibilities for 4D bioelectronics.The structures' multifaceted bends, capable of providing numerous folds beyond their face count, open up new avenues for flexible microelectronic interconnection research and development.For instance, the 93% foldability and the low strain (viz. up to 0.09%), as assessed in the sharp-angle Miura-Ori tessellation (Figure 2c.2), make our 4D manufacturing process attractive for enhancing the density of functional materials in high-end energy applications.Our micro-origami waterbomb tessellation also attests to the successful fabrication of dynamic-shape auxetic structures with submicrometer-sized cylindrical curvatures.This achievement holds great potential for applications in the packaging and delivery of small objects or drugs within intricate systems and in the emulation of peristalsis in artificial organs as well as in the adaptive hosting of implantable smart biomedical devices.
To validate the adaptability and scalability of our approach in light of the potential applications, we provided two proof-ofconcept demonstrators.First, we presented the morphogenetic supercapacitor, a bio-inspired device that can deliver exceptional areal capacitance (≈90 mF cm −2 ) and may enable highdensity energy conversion and storage applications (Figure 3).The power density of the dynamic shape device was superior to 100 mW cm −2 at FL > 55%, a remarkable outcome attesting to its potential toward ultra-flexible and autonomous bioelectronic applications.As noted, the future integration of high-end materials (e.g., activated carbon and carbon nanotubes, MXene, graphene, and reduced graphene oxide) within dynamic-shape electronics has the potential markedly to improve the surface en-ergy density, power density, and areal capacitance of the stateof-the-art energy storage technologies.Concerning the second proof-of-concept achievement, we introduced a soft implant prototype whose shape can be controlled either chemically or electronically using the hybrid-hinge actuation principle (Figure 5).Given the significant challenge of designing electronic devices that can manage the constant stress caused by the hemodynamic conditions in the body, we emphasize the hybrid-hinge dynamicshape prototypes stand up as particularly promising candidates for developing new electronically morphable intelligent biomedical implants.Such a 4D bioelectronic technology would be particularly useful in scenarios where there is a need for frequent adjustments to the implant, as this method allows for real-time shape customization.By implementing this technology, medical professionals will be able to address the unique needs and requirements of each patient with greater accuracy and precision, leading to improved patient outcomes.
In summary, by combining micro-origami tessellation assembly strategies and designs, we achieved unconventional 4D microelectronics.Our 4D fabrication approach allowed for integrating several functional materials, including thin films, nanomembranes, flexible substrates, stimuli-responsive hydrogels, organic mixed ionic-electronic conductors, and electroactive artificial muscles.We meticulously designed, fabricated, and characterized active-hinge micro-origami tessellations, monitoring their assembly and dynamic folding behavior while assessing their main figures of merits for flexible electronic integration as well as energy-conversion and biomedical applications.Our method grants precise chemical and electronic control over the shape formation and morphing of these tessellation microstructures.Our findings advance the development of multidimensional, morphable metamaterials seamlessly compatible with biological-and electronic systems, boasting a new vista for tunable topologies in 4D electronics via morphogentronics.

Experimental Section
Host-Substrate Cleaning: Glass slides (23 mm × 23 mm) were employed as host substrates for the fabrication of the flexible micro-origami tessellations.For cleaning, the glass slides were immersed in acetone and isopropyl alcohol for 10 and 5 min, respectively.During this period, the substrates were subjected to an ultrasonic bath.Subsequently, a 5-minute oxygen (O 2 ) plasma cleaning (400 W) was performed using a GIGAbatch Series Microwave Plasma System to remove organic residues from the substrate.
Polymeric Materials Synthesis: The photosensitive SL solution was synthesized using acrylic acid, hydrated lanthanum(III) chloride, and 2-Benzyl-2-(dimethylamino)-4-morpholinobutyrophenone (DBMP). [83]The photosensitive HG solution was synthesized employing (Hydroxyethyl)methacrylate, poly(ethylene-alt-maleic anhydride), N, N-Dimethylacetamide (DMAC), and DBMP. [83]The photosensitive PI solution was synthesized using 3,3′,4,4′-Benzophenonetetracarboxylic dianhydride, 4,4′-Diaminodiphenylmethane, DMAC, dimethyl-aminoethyl methacrylate, and DBMP. [83]reparation of HG Hinges on Flexible Joints and Substrates: After substrate cleaning, a ≈200 nm-thick SL was patterned on the glass slides.The SL solution was deposited by spin-coating at 3000 rpm for 60 s on a clean glass substrate followed by a soft bake at 35 °C for 3 min.The sample then was exposed to 350 nm-UV radiation using a Karl Süss MA6 Mask Aligner.The exposed patterns were developed in deionized water, dried, and then rinsed in propylene glycol monomethyl ether acetate (PGMEA).In addition, the samples were hard baked at 220 °C for 15 min.Subsequently, ≈680 nm-thick HG layers were patterned on the SL to form the microorigami tessellation's VHs.The HG solution was spin-coated at 5000 rpm for 45 s, and exposed to UV using the MA6 Mask Aligner.The developing process was performed in diethylene glycol monoethyl ether (DEGMEE) followed by rinsing in PGMEA.Then, the sample was hard baked at 220 °C for 15 min.Subsequently, the PI FS bearing 500-900 nm thickness was patterned on the as-fabricated structures.The PI FS was designed to hold the micro-origami walls, HG flexible joints, and the tessellation's tetherand anchor structures.The PI solution was deposited on the substrate by spin-coating at 6000 rpm for 60 s.The samples were then exposed to UV and further developed in a solution containing ethanol, DEGMEE, and N-Ethyl-2-pyrrolidone (1:2:4 parts per volume).After exposure, a hard bake procedure was carried out at 220 °C for 15 min.Afterward, ≈4.6 μm-thick SU-8 3005 films were patterned on the micro-origami sample to play the role of rigid walls.The SU-8 photoresist was spin-coated at 5000 rpm for 30 s.The UV exposure was performed using a Heidelberg MLA100 Maskless Aligner, whereas the developing process was performed using mr-DEV 600 solution.O 2 plasma was employed to treat the SU-8 surface before the hinge patterning.Finally, ≈680 nm-thick HG layers were patterned on the PI valley joints, using the aforementioned procedure, to form the micro-origami tessellation's MHs.Finally, the release of the microorigami tessellation from the substrate occurred with the chemical etching of the SL in an ethylene-diamine-tetraacetic acid (EDTA) solution (pH = 4).
Origami Simulation: The micro-origami tessellation FL and maximum strain were calculated using the Origami Simulator application developed by Ghassaei et al., [57] and implemented in an open-source graphics processing unit available online.The Origami Simulator is capable of solving for subsequent small displacements in the geometry of a sheet due to forces exerted by hinges, as required by our HG-actuatorbased micro-origami tessellations.For the simulations, we employed a first-order numerical integration (viz.Euler method), and the optimized parameters were as in the following: axial stiffness = 20 N m −1 , face stiffness = 0.2 N m −1 , fold stiffness = 0.25 N m −1 , facet crease stiffness = 3 N m −1 , and damping ratio = 0.45.The FL-dependent maximum strain distributions were calculated for Miura-Ori, sharp-angle Miura-Ori, Resch-triangle, and waterbomb tessellation geometries.
Chemo-Mechanical Characterization: The chemo-mechanical actuator responsivity was evaluated as a function of pH.For the chemo-mechanical essays, pH-adjusted DEGMEE solutions were prepared using AZ 726 MIF developer as an additive.Additionally, hydrochloric acid (HCl) solutions were prepared and pH-adjusted to provide pH < 3. The as-prepared solutions were then stabilized at pH = 1, 2, 3, 4, 5, 6, 7, 8, and 9, and stored at dark environmental conditions.Before the chemo-mechanical essays, each pH was measured using a universal pH test paper strip.The samples were immersed in the pH-adjusted solutions, and the steady-state deformations were achieved by the micro-origami tessellations after ≈20 min.Steady-state fold images of the micro-origami tessellations in the respective pH-adjusted solutions were captured using a Keyence VHX Digital Microscope.The samples were immersed in deionized water before starting the experiments and after every pH-dependent actuation to avoid crosscontamination of solutions and guarantee similar initial conditions.
Microelectronics Fabrication: Standard photolithography processes, physical vapor deposition, and electrochemical deposition were combined to provide integration of robust electronic counterparts with the microorigami tessellations.AZ5214E photoresist (MicroChemicals) was spincoated at 4500 rpm for 45 s.The exposure was done using a Heidelberg MLA100 Maskless Aligner.Electron-beam evaporation was performed to deposit CC materials, namely a 60 nm thick chromium (Cr) film followed by a 120 nm thick Au film.Lift-off processes were carried out to get the successful metal patterning.Nickel (Ni) and Au micrometer-thick films were electroplated on the CC plates (using Ni-and Au-plating solutions acquired from Tifoo) to play the role of rigid walls in the bio-inspired morphogenetic supercapacitors based on HG hinges.Ni and Au depositions were performed using direct current (viz.6 and 40 mA cm −2 , respectively) and the CCs as working electrodes, whereas a platinum (Pt) wire was employed as the counter-electrode.After the release of the micro-origami tessellation, PEDOT 600-900 nm thick films were electrodeposited on the CCs using chronoamperometry by applying 0.9 V.The electrodeposition was carried out using CC as the working electrode, Ag/AgCl as the reference electrode, and a Pt wire as the counter electrode.For the dynamic-shape implant prototype, the 10 nm thick Cr followed by 50 nm thick Au metal grids were deposited by electron-beam evaporation.The SU-8 rigid facets and the HG MHs, deposited and patterned subsequently, also played the role of passivation layers for the metal grids, allowing the PPy hinges to be electrochemically deposited at the pre-designed regions (Figure S11b, Supporting Information).
Micro-Origami Tessellation's Collector Wires: Nanometer-thick Cr/Au films, whether freestanding or patterned on thin, flexible substrates, are expected to exhibit inherent flexibility, allowing radii of curvature down to the range of a few μm.This malleability has been demonstrated in different scenarios that confirmed that applying these connectors in origami hinges is a generally viable approach.Merces et al. demonstrated that patterned Cr/Au thin films can be applied as external electrodes of a membrane that rolls up and forms a mechanically compliant Swiss roll structure with a radius of ≈3 μm. [15]Such a coiled electrode preserves the electrical and mechanical characteristics of the Cr/Au film, allowing the flexible device to apply with high sensitivity to pressure sensing.Ferro et al. showed that Cr/Au thin films can also be used as electrodes that deform inside the cavity of Swiss-roll microtubes. [18]In this scenario, the Cr/Au thin films were curved into radii of ≈10 μm, maintaining electrical and mechanical characteristics to sense biomarkers in high-gain electrochemical transistors.Here, we attested the mechanical compliance and electrical stability of Cr/Au connectors using them as current collectors in PPy actuators (Figure S10a, Supporting Information).After PPy electrodeposition, the polyimide was released from the glass, and the sample was used as an electromechanical actuator (Figure S10b, Supporting Information).The curvature of the Cr/Au electrode at the hinge changes from centimeters to tens of micrometers in a reproducible manner during several consecutive cycles (Video S1, Supporting Information).When applied to origami hinges, Cr/Au thin films achieved radii of curvature as small as 10 μm.Such a curvature variation represents a reliable working range for the chosen collector materials.
Finite-Element Calculation: We used a model consisting of surface objects to simulate our structure and 3D geometries for the surrounding box and contacting electrodes.Finite conducting boundary conditions were applied to the conductors, with Au having a conductivity of 4.1 × 10 7 S m −1 and a two-sided layer with a thickness of 180 nm.The PI polymer layer was used as a finite conducting boundary condition with a conductivity of 1.0 × 10 −4 S m −1 and a two-sided layer with a thickness of 1 um for the origami.The surrounding box was filled with seawater, with an adjusted conductivity of 5 × 10 −1 S m −1 to represent the PBS (phosphate buffer solution).Copper material was used for the contact pads to our structure without any modifications (physical dimensions: 100 × 20 × 60 μm, with 100 × 60 μm sides contacted to the surrounding box and our structure).A wave port terminal was applied to the same contacting surface of the surrounding box, while differential terminal sources with 1 V, 0°and 180°p hases were applied to the left and right copper contacts.Mesh modification with the maximum length of the element set to 10um was applied on the CCs, and a 1 Hz excitation frequency was used.For the field overlay, we used the electric field magnitude applied to the structural conducting elements, normalizing its minimum and maximum limit scales to the same values for the three origami folded cases.
Supercapacitor Electrochemical Characterization: Galvanostatic charge-discharge, cyclic voltammetry, and EIS were carried out using Autolab PGSTAT204 and μAutolab (Type III) potentiostats (Metrohm).All electrochemical measurements were performed using 0.1 m sodium chloride (NaCl) prepared in 0.1 mm PBS as the electrolyte, whereas polydimethylsiloxane (PDMS) mold was used to contain the excess liquid during the measurements.For the galvanostatic charge-discharge measurements, the operating voltage varied from −0.64 to 0.64 V, whereas the absolute current applied for charge and discharge cycles were in the 20-80 and 20-60 μA ranges, respectively, as summarized in Table S1 (Supporting Information).The cyclic voltammetry measurements were done at 0.3 V s −1 scan rate, within a 0-0.5 V potential window to prevent electrical instabilities.The EIS was carried out at the 1 × 10 −1 -5 × 10 4 Hz range using a 0.01 V signal amplitude.The areal capacitance and energy density were calculated using the sharp-angle Miura-Ori tessellation's FL-dependent footprint area, as shown in Figure 4d.1.
Polymeric Materials Biocompatibility: We argue that our bio-inspired dynamically morphing structures and devices are very attractive candidates for use in biomedical applications.Attesting of the apparent biocompatibility of the as-designed platform, the PI substrates represent a benchmark for high-performance polymers on the basis of a remarkable collection of valuable traits and accessible production pathways.PI FSs have called considerable attention from the biomedical field because they are also suitable for sterilization by robust methods.Recent contributions show that various PIs can accommodate in vivo conditions in which they are able to function for a long time without compromising the living tissue functions. [84]The second-abundant functional material in our dynamically morphing structures is SU-8, which plays the role of rigid walls.SU-8 is an epoxy-based photoresist that has been extensively utilized to fabricate myriads of devices including biomedical devices in recent years.Although SU-8 might not be completely biocompatible, existing surface modification techniques, such as the O 2 plasma treatment used here, might be sufficient to minimize biofouling caused by SU-8. [85]Third, the actuator hinges -responsible for providing the dynamic shape configurations to the micro-origami tessellations -also depict interesting biocompatible properties.HG materials of natural or synthetic origins are very suitable candidates for fabricating biocompatible scaffolds, [86] whereas PPy thin films are excellent runners for achieving high electric conductivities and promising cytocompatibility in future biomedical applications. [87]Py Actuator Working Principle: The smart biomedical implant morphability is provided by integrated PPy electromechanical actuators, which are obtained by oxidative polymerization of pyrrole (Py) on flexible joints.Besides the excellent electrical characteristics displayed by PPy thin films, [88] these structures have been intensively investigated as a biomaterial due to their environmental stability and biocompatibility.[87] Recent research has shown that PPy-based materials are important players in the development of scaffolding materials or interfaces to mediate electrical stimulation to human cells or tissues, such as in cancer therapy or tissue regeneration.[89] Furthermore, as recently demonstrated by Rivkin et al., [20] the actuation performance (viz.curvature as a function of the FSand PPy thicknesses) makes the PPy actuator an appropriate candidate for applications in thin-film and microscale devices.Figure S10 (Supporting Information) exhibits the PPy electromechanical actuation working principle, evidencing the material suitability to be employed as micro-origami hinges.The PPy chemical structure after Py polymerization is shown at the top of Figure S10a (Supporting Information).The Py polymerization takes place at the surface of the working electrode (viz.Cr/Au stripe), which was previously patterned on the PI FS.The PPy thin-film actuation is driven by the redox-induced influx or repulsion of hydrated ions such as Na + , as illustrated at the bottom of Figure S10a (Supporting Information).Such a redox-induced Na + pump can reliably be achieved by controlling the electrical stimulus sweep to guarantee PPy redox (quasi)reversibility. WhenPPy is oxidized, the virtually positively charged chains repulse the Na + species, deflating the PPy thin film and causing the hinge to fold up.The subsequent PPy reduction causes the thin film re-swelling, which recovers the initial volumes of the PPy chains and, consequently, the PPy hinge unfolds.Figure S10b (Supporting Information) exhibits the cyclic voltammetry curve acquired at 0.1 V s −1 during a stable actuation cycle performed in 0.1 m NaDBS solution using the PPy-hinge actuator stripe, whereas its subsequential actuation cycles are shown in the Video S1 (Supporting Information). In Fgure S10b (Supporting Information), the left and right insets respectively show the optical microscopy images of the unfoldedand folded states achieved by the stripe hinges.
Fabrication of PPy Electromechanical Actuator Hinges: Py monomers (99% pure, 67.09 g mol −1 , acquired from Thermo Scientific) were distilled and then employed to prepare a polymerization solution (0.1 m Py, 0.1 m NaDBS aqueous solution).The monomer solution was roll-mixed for 20 min to obtain a homogeneous 0.1 m Py solution.Using Autolab PGSTAT204 potentiostat (Metrohm), +0.8 V versus Ag/AgCl was applied to the samples to polymerize a layer of PPy onto the Cr/Au electrodes.Given t PI ≈ 0.5 μm (Figure S9a, Supporting Information), we adjusted the Py polymerization process to achieve PPy actuator hinges of ≈2 μm thickness to optimize the curvature of the electromechanical hinge.This adjustment is evident in the height profile at the top of Figure 5c.2.Height profiles collected during the hybrid-hinge tessellation fabrication are available in Figure S9b (Supporting Information).After deposition, the sample was removed from the monomer bath, rinsed with deionized water, and immersed in the SL etching solution.
Electromechanical Characterization of PPy Actuator Hinges in the Hybrid-Hinge Prototype: After SL etching, the freestanding samples were rinsed in isopropyl alcohol and then immersed in 0.1 m NaDBS solution (5 < pH < 6) for geometry stabilization and assembly.Afterward, the samples were immersed in a three-electrode electrochemical cell with 0.1 M NaDBS solution as the electrolyte, and the actuators were activated with a cycling potential between zero and 1 V versus Ag/AgCl with a 0.1 V s −1 scan rate.Due to the complex grid of PPy actuators interconnected in series and parallel within the hybrid-hinge system (Figure S11c, Supporting Information), each actuator position on the tessellation exhibits varying electrical resistance.To circumvent this issue and enhance the tessellation's actuation reversibility, we employed voltage pulse trains that ensure stepwise redox reactions, ion migration, and actuation as well (Figure S12, Supporting Information).By adjusting the amplitude, duration, and interval of the pulse train, we could access different waterbomb shapes, resulting in FL changes ranging from ≈18% to ≈67%, as demonstrated in Figure 5e.1-e.6.Actuators were successfully operated in 0.1 m NaDBS (pH between 5 and 6) by cyclic voltammetry (stripe electrode, Figure S10, Supporting Information) and pulse trains (hybrid-hinge prototype, Figure 5).A pulse train with a −1 V amplitude, 20 s width, and 40 s interval drove the stepwise oxidation of PPy along the tessellation surface during the initial 80 minutes (Figure 5e; Figure S12a,b, Supporting Information), leading to the effective folding of the hybrid-hinge tessellation to FL = (67 ± 7)%.In the subsequent 60 min, a second pulse train with a −1.2 V amplitude, 114 s width, and 6 s interval facilitated the stepwise reduction of PPy hinges (Figure S12a,c, Supporting Information), effectively unfolding the hybrid-hinge tessellation back to FL = (20 ± 3)%, nearly equal to the initial value of ≈18%.

Figure 1 .
Figure1.Biocompatible dynamically-morphing mesostructures carrying electronic devices.a) State-of-the-art structures, challenges, and promising biomedical applications.Dynamically morphing behavior enabled by micro-origami tessellations: tessellation crease pattern (a.1), dynamically shaped cylindrical tube (a.2), and auxetic shell (a.3).Technological advances in this field may benefit energy-and power density, electronic component density, and electronic information processability.Envisioned dynamically morphing devices may be deployed to aid in the rehabilitation and ongoing monitoring of various medical conditions including embolized aneurysms (a.4), endobronchial diseases (a.5), atherosclerosis (a.6), and peripheral nerve injuries (a.7).b) Morphogentronics approach proposed for the creation of dynamically morphing micro-origami tessellations: actuator hinge patterning on flexible joints and substrates (b.1), providing functional space for flexible electronics counterpart integration (b.2), and giving rise to actuator-hinge foldable device units (b.3).The monolithic integration and 4D fabrication enable the manufacture of several subsequent foldable units into the multifaceted tessellation (b.4), giving rise to complex 4D microelectronic tissues (b.5).

Figure 2 .
Figure 2. Dynamic shape micro-origami tessellations based on stimuli-responsive hinges.a) Architectures and HG-hinge micro-origami tessellation structures: Miura-Ori (a.1), sharp-angle Miura-Ori (a.2), Resch-triangle (a.3), and waterbomb (a.4).b) Optical microscopy images of the 4 micro-origami tessellations as-fabricated (b.1-b.4,respectively).c) Confocal microscopy images of the micro-origami tessellations (c.1-c.4,respectively) at different folding configurations driven by pH, which increased from left to right.Scale bars in panels b and c: 500 μm.d) FL and maximum strain distribution calculated for the micro-origami tessellations (d.1-d.4,respectively).e) Quantitative evaluation of FL and maximum strain: FL as a function of pH (e.1), maximum strain as a function of FL (e.2), and maximum strain as a function of pH (e.3).The symbols correspond to experimental data, whereas the dotted rectangles point out FLs as shown in panel d.The dashed lines in (e.1) are eye guides, whereas the statistical errors arise from the evaluation of 4 samples at the experimental condition.Error bars in panels (e.2,e.3) were propagated from FL.

. 1 )
or an expanded leaf (Figure 3a.2), the exploded view in Figure 3b introduces the concept of the highdensity, bio-inspired morphogenetic supercapacitor.The supercapacitor architecture (Figure 3b.1) incorporates a current collector (CC) array patterned on the flexible substrate.An extra backside array (b-CC), designed to enhance the device's electrochemically active area immediately after the supercapacitor's release, is directly patterned on the SL.For clarity, top and bottom views of the patterned supercapacitor are presented in Figure 3b.2,b.3,whereas the 30°-50°HG-hinge veins (as inspired by the deployable hornbeam leaves) are indicated inset.An optimized spatial arrangement is proposed for the supercapacitor's positive and negative plates, distinguished by cyan (CC + and b-CC + ) and yellow (CC − and b-CC − ) colors, respectively (Figure 3b.2,b.3).This design serves two critical purposes: 1) minimizing leakage current across the flexible substrate and 2) facilitating the observation of capacitive current.

Figure 3 .
Figure 3. Bio-inspired morphogenetic supercapacitor based on chemo-mechanical hinges.a) Origami-based functional implementation observed in nature (viz.the hornbeam Carpinus betulus' leaf): compact developable leaf (a.1), and deployed leaf after shape expansion (a.2). b) Sharp-angle Miura micro-origami device realization: exploded view of the supercapacitor component layers (b.1), top-view exhibiting the CCs and MHs (b.2), and backview exhibiting b-CCs and VHs (b.3).c) Optical microscopy images of the morphogenetic supercapacitor: expanded-and folded sharp-angle Miura tessellation (c.1), and supercapacitor front and back views (c.2 and c.3, respectively).The tessellation folded package in (c.1) was artificially colored to improve the visualization.d) Multifocal composition shows the bio-inspired veins of the device.The mass-transportation path along the electrolyte, due to CC + (cyan) and CC − (yellow), is also illustrated in panel (d), whereas the detailed sketch (cation-drift oriented) is depicted in the top inset.Scale bars in panels c and d: 500 μm.