Daniil Karnaushenko

The integration of rigid microscale electronics onto soft and flexible polymer substrates remains a key challenge for flexible electronics, biointegrated systems, and body‐first microrobotics, where the mechanical body, material architecture, morphology, and primary functions are designed first, while the electronic processing unit (e.g., a Si CMOS chiplet), acting as the brain to control the robot´s functionalities, is integrated later. Existing approaches, including anisotropically conductive adhesives and transfer printing, rely on non‐patternable or particle‐based interconnects, thick bonding layers, or complex processing, constraining interconnect density, scalability, and compatibility with mechanical transformations such as bending, rolling, or folding. Here, we present a patterned solid–liquid interdiffusion (SLID) bonding approach enabling deterministic, fine‐pitch heterogeneous integration on ultrathin polymer substrates compatible with standard microfabrication. Electroplated Cu/Sn pillar bumps fabricated on 5 µm polyimide are systematically characterized to define geometric, electrical, and mechanical process window for reliable SLID bonding. The resulting interconnects exhibit controlled solder reflow, low electrical resistance, high mechanical robustness, and minimum inter‐pillar spacings of 10 µm without adhesives or conductive particles. Microscale light‐emitting diodes bonded by SLID remain functional during self‐rolling, bending and folding‐driven three‐dimensional assembly with integrated silicon microchips. This work provides a scalable framework for mechanically reconfigurable microrobotic and flexible microsystems.

Thin-film self-assembly of three-dimensional (3D) microsystems presents a compelling route to integrate complex functionalities into ultra-compact volumes; yet, strategies for incorporating tunable ion-conducting elements remain limited. Here, we introduce a strain-induced self-assembly platform that transforms lithographically patterned multilayer thin films into functional 3D coaxial Swiss-roll microtubes with total active volumes below 1 µL. A key innovation is the monolithic integration of a chemically tunable polyimide proton exchange membrane, enabling post-fabrication optimization of ionic transport that balances proton transport with mediator blocking. We further implement a dual-mode operational scheme that decouples microbial metabolism from electrochemical power generation, revealing biofouling, not chemical fouling or membrane degradation, as the dominant failure mechanism in conventional architectures. Critically, optimally treated polyimide membranes exhibit excellent recoverability after fouling, while cell-free mode operation maintains stable performance by physically excluding microorganisms from the microelectronic environment. This integrated bio-electronic microsystem achieves a volumetric power density of ~ 3.1 mW cm⁻ ³ within an ultra-compact footprint of 4.16 mm ² . Our work establishes a scalable thin-film engineering approach to create tunable, 3D bioelectronic power sources for autonomous microsystems. Graphical Abstract

True microrobots, in contrast with externally controlled microparticles, must harvest or carry their own source of energy, as well as their own (preferably programmable) microcontroller of actuators for locomotion, using information acquired from their own sensors. We demonstrate here, for the first time, that microrobotic smartlets, hitherto buoyancy divers, can also be equipped to navigate in 2D on surfaces, with onboard control responding to both sensor information and their internal electronic program. Fabricating modular microrobots, with all dimensions of 1 mm and below, has been difficult to achieve because of competing demands for the limited surface area and the challenges of integrating and interconnecting the diverse functionalities of energy harvesting, actuation, sensing, communication, docking, and control. A novel high‐density heterogeneous integration, via soft‐substrate micro flip‐chip bonding of custom CMOS and LED microchiplets onto fold‐up polymer surfaces, compatible with roll‐up isotropic ambient light harvesting, now makes this possible. Fabricating electrolytic bubble actuators on multiple cube faces and connecting them to a custom sensor‐controlled onboard microchiplet (lablet) allow the smartlets to locomote on wet surfaces, changing direction in response to both timed programmed control as well as programmed response to locally sensed signals. Such locomoted robotic microcubes can also move to and selectively dock with other modules via patterned surfaces. This is powered by ambient light in natural aqueous media on smooth surfaces.

Biological systems seamlessly integrate energy storage and actuation within compact architectures, whereas synthetic approaches largely implement these functions as separate components. Conjugated polymers can couple both, yet their operation relies on ion insertion accompanied by hydration water within the polymer backbone, creating an intrinsic trade-off between performance and stability. Here we show that anion hydration governs this trade-off. In-operando Raman spectroscopy and time-resolved mass measurements reveal that reducing anion hydration suppresses water ingress, mitigates backbone degradation and converts the polymer response from a two-step swelling process into a single, rapid volumetric relaxation. Leveraging this principle, we realize a sub-millimetre monolithic device that integrates energy storage and actuation within a 0.56 mm ² footprint. A centrally configured dual-cell microbattery delivers 161 mAh cm ^-2 and reduces the energy consumption of surrounding actuators by fourfold. Hydration control, as the governing design parameter for multifunctional devices, holds translational promise for integrated energy–motion architectures at the microscale.

Modular microrobotics can potentially address many information-intensive microtasks in medicine, manufacturing, and the environment. However, surface area has limited the natural powering, communication, functional integration, and self-assembly of smart mass-fabricated modular robotic devices at small scales. We demonstrate the integrated self-folding and self-rolling of functionalized patterned interior and exterior membrane surfaces resulting in programmable, self-assembling, intercommunicating, and self-locomoting micromodules (smartlets ≤ 1 cubic millimeter) with interior chambers for onboard buoyancy control. The microrobotic divers, with 360° solar harvesting rolls, functioned with sufficient ambient power for communication and programmed locomotion in water via electrolysis. The interior folding faces carried rigid microcomponents, including silicon chiplets (Si chiplets) as microprocessors and micro–light-emitting diodes (LEDs) for communication. The exterior faces were able to engage in specific patterned docking interactions between smartlets. The heterogeneous integration is mass producible and affordable through two-dimensional (2D)–automated lithography and microchiplet bump-bonding processes, here shown to be compatible with subsequent autonomous 3D folding and rolling. The robotic modules functioned in natural aqueous environments, and the technology was analyzed as scalable down to microscopic dimensions. Selectively addressed communication with individual smartlets was enhanced via frequency-specific optical signals and enabled precise control, allowing each smartlet to be activated independently within a collective system. The work remodels modular microrobotics closer to the surface-rich modular autonomy of biological cells and provides an economical platform for microscopic applications.

Active sensing matrices play a pivotal role in various electronic devices, including optical and X‐ray imaging arrays, electronic skins, and artificial tactile arrays, among others. These matrices function through a thin‐film active switching mechanism, allowing for the scanning of rows and columns by external circuitry to read the sensory signals of individual pixels. Recently, indium–gallium‐zinc oxide thin‐film transistors (IGZO TFTs) have emerged as highly promising technology in the realm of flexible electronics. They enable the large‐scale integration of functional circuits on flexible substrates. Shift registers are commonly employed as peripheral scanning circuits to sequentially address active‐matrix arrays. To enhance system compactness and minimize external electrical connections, it is imperative to seamlessly integrate shift registers within the active matrices. However, contemporary flexible IGZO‐based shift registers suffer from high operating voltages and low frequencies, which constrain their applicability in high‐performance flexible sensors and displays. In response to this challenge, a breakthrough is presented in the form of low‐voltage, high‐frequency bootstrap shift registers implemented with flexible IGZO technology. The approach involves utilizing SU‐8 buffered polyimide (PI) polymer foils as substrates. These foils boast an exceptional level of surface smoothness, significantly increasing the yield and performance of electronic components, including vias, IGZO TFTs, and capacitors used in the shift register circuitry. Additionally, HfO₂/Al₂O₃/HfO₂ sandwich structures are employed as high‐k dielectric layers to reduce the operational voltage. Thanks to the innovative circuit design and optimized fabrication methods, the 16‐stage shift register can operate at just 1.8 V with a frequency of 15 kHz. This breakthrough promises to have a profound impact on a wide range of applications for driving flexible active‐matrix electronic systems.

Modification of the magnetic properties under the induced strain and curvature is a promising avenue to build three-dimensional magnetic devices, based on the domain wall motion. So far, most of the studies with 3D magnetic structures were performed in the helixes and nanowires, mainly with stationary domain walls. In this study, we demonstrate the impact of 3D geometry, strain and curvature on the current-induced domain wall motion and spin-orbital torque efficiency in the heterostructure, realized via a self-assembly rolling technique on a polymeric platform. We introduce a complete 3D memory unit with write, read and store functionality, all based on the field-free domain wall motion. Additionally, we conducted a comparative analysis between 2D and 3D structures, particularly addressing the influence of heat during the electric current pulse sequences. Finally, we demonstrated a remarkable increase of 30% in spin-torque efficiency in 3D configuration.