Highly flexible, foldable, and rollable microsupercapacitors on an ultrathin polyimide substrate with high power density.

The design and functionality of extremely flexible, foldable, and rollable microsupercapacitors (MSCs) with in-plane interdigital electrodes that consist of single-walled carbon nanotube (SWCNT) networks on an ultrathin polyimide substrate are demonstrated through experiments and finite element simulations. The all-solid-state MSCs can be reversibly bent, folded, and rolled purely elastically without degradation of their electrical performance. The simulation results confirm that the deformation in bent, folded, and rolled MSCs is purely elastic. The high power density (1125 W cm-3) and small time constant (1 ms) of the present MSCs are comparable to those of aluminum electrolytic capacitors. The MSCs operate at scan rates of up to 1000 V s-1, are characterized by a volumetric capacitance of 18 F cm-3 and an energy density of 1.6 mWh cm-3, and exhibit superior electrochemical stability with 96% capacity retention even after 100,000 charge/discharge cycles. The developed MSCs demonstrate high potential for integration in flexible and wearable electronic systems

Ultrafast Biomimetic Untethered Soft Actuators with Bone‐In‐Flesh Constructs Actuated by Magnetic Field

Soft actuators with unique mechanics have gained significant interests for unique capabilities and versatile applications. However, their actuation mechanisms (usually driven by light, heat, or chemical reactions) result in long actuation times. Reported magnetically actuated soft actuators can produce rapid and precise motions, yet their complex manufacturing processes may constrain their range of applications. Here, the “bone-in-flesh” is proposed that constructs combining rigid magnetic structures encapsulated within soft polymers to create untethered magnetic soft actuators. This approach enables these soft, impact-resistant, agile actuators with a significantly simplified fabrication process. As demonstration examples, multiple soft actuators are fabricated and tested, including actuators for auxetic properties, 2D–3D transformations, and multi-stable states. As such, this work offers a promising solution to challenges associated with soft actuators to potentially expand their applications in various domains

Kirigami-inspired, highly stretchable micro-supercapacitor patches fabricated by laser conversion and cutting.

The recent developments in material sciences and rational structural designs have advanced the field of compliant and deformable electronics systems. However, many of these systems are limited in either overall stretchability or areal coverage of functional components. Here, we design a construct inspired by Kirigami for highly deformable micro-supercapacitor patches with high areal coverages of electrode and electrolyte materials. These patches can be fabricated in simple and efficient steps by laser-assisted graphitic conversion and cutting. Because the Kirigami cuts significantly increase structural compliance, segments in the patches can buckle, rotate, bend and twist to accommodate large overall deformations with only a small strain (<3%) in active electrode areas. Electrochemical testing results have proved that electrical and electrochemical performances are preserved under large deformation, with less than 2% change in capacitance when the patch is elongated to 382.5% of its initial length. The high design flexibility can enable various types of electrical connections among an array of supercapacitors residing in one patch, by using different Kirigami designs

Mechanics Design for Stretchable, High Areal Coverage GaAs Solar Module on an Ultrathin Substrate,”

The trench design of substrate together with curvy interconnect formed from buckling provides a solution to stretchable electronics with high areal coverage on an ultrathin substrate, which are critically important for stretchable photovoltaics. In this paper, an improved trench design is proposed and verified by finite element analysis (FEA), through use of a heterogeneous design, to facilitate strain isolation and avoid possible fracture/delamination issue. A serpentine design of interconnect is also devised to offer $440$90%

Moisture self-regulating ionic skins with ultra-long ambient stability for self-healing energy and sensing systems

Dehydration has been a key limiting factor for the operation of conductive hydrogels in practical application. Here, we report self-healable ionic skins that can self-regulate their internal moisture level by capturing extenral moistures via hygroscopic ion-coordinated polymer backbones through antipolyelectrolyte effect. Results show the ionic skin can maintain its mechanical and electrical functions over 16 months in the ambient environment with high stretchability (fracture stretch ∼2216 %) and conductivity (23.5 mS/cm). The moisture self-regulating capability is further demonstrated by repeated exposures to harsh environments such as 200°C heating, freezing, and vacuum drying with recovered conductivity and stretchability. Their reversible ionic and hydrogen bonds also enable self-healing feature as a sample with the fully cut-through damage can restore its conductivity after 24 h at 40 % relative humidity. Utilizing the ionic skin as a building block, self-healing flexible piezoelecret sensors have been constructed to monitor physiological signals. Together with a facile transfer-printing process, a self-powered sensing system with a self-healable supercapacitor and humidity sensor has been successfully demonstrated. These results illustrate broad-ranging possibilities for the ionic skins in applications such as energy storage, wearable sensors, and human-machine interfaces

Stretchable Electronics and Soft Actuators via Elastic Instability Design and Facile Fabrication

Soft and deformable electronics and actuators have attracted high research interests toward practical applications. This work focuses on two goals: (1) applying the concept of elastic instability in the structural design for soft systems; and (2) exploring rapid and low-cost schemes for their facile fabrications. Specifically, Kirigami, curved serpentines, auxetics, bistable and multistable structures, have all been utilized in different electronics and actuator systems to obtain unique and desirable properties, such as ultrahigh deformability, omnidirectional stretchability, and impact-resistant mechanics in this work.First, a construct inspired by Kirigami designs has been developed to make highly deformable micro-supercapacitor patches with high areal coverages of electrode and electrolyte materials. These patches are fabricated in simple and efficient steps by a laser assisted graphitic conversion and cutting process, utilizing different laser power and scanning speeds on a laser cutter. The Kirigami cuts significantly increase the structural compliance such that individual segments in the patches can buckle, rotate, bend and twist to accommodate large overall deformations with only a small strain in active electrode areas. Electrochemical testing results have proved that electrochemical performances are preserved under large deformations up to 282.5% of overall structural elongations.A time- and cost-effective fabrication approach to construct stretchable electronics with the “island-bridge” constructs has been established without using photomasks. A low-cost commercially available vinyl cutter is used to define patterns by adjusting the cutting force and depth on the blade. Metal interconnects and pads can be patterned via the “tunnel cut” process and the flexible overall structure can be defined via the “through cut” process. The capabilities of the proposed method is shown by two demonstration devices, a skin-mounted module for monitoring breathing and a water-resistant supercapacitor array with omni-directionally stretchable capability. These devices can accommodate large deformations through the buckling and post-buckling instability without affecting their functions.Finally, a class of magnetically powered, untethered soft actuators has been built based on a bioinspired “flesh-and-bone” construct. This construct has both key attributes of fast actuation and compliant impact-resistant mechanics and it also renders a simple fabrication process using generic 3D printers and off-the-shelf neodymium magnets as well as silicone elastomers. Actuators of diverse shapes of elastomeric “fleshes” and different placements of magnetic “bones” have displayed several distinct types of tasks, including auxetic expansion and shrinking, out-of-plane transformations, transition among multiple stable states, and manipulation of small objects

Mechanical designs employing buckling physics for reversible and omnidirectional stretchability in microsupercapacitor arrays

Stretchable electronics draw widespread attention with reported applications in various sectors, including health care, optoelectronics, and energy. However, irreversible interconnect deformation and direction-dependent stretchability may greatly limit the longevity and functionality of many stretchable systems operating under multidirectional, repetitive loading and unloading conditions. In this work, we introduce mechanical designs that can significantly enhance reversible, omnidirectional stretchability in a typical microsupercapacitor array. Simulation results from a series of computational studies demonstrate that structural buckling followed by out-of-plane deformation of interconnects are the fundamental physical mechanisms responsible for the increased stretchability. The present analytical methodology provides a computational framework for the effective design of other electronic systems with demanding deformability requirements

Highly flexible, foldable, and rollable microsupercapacitors on an ultrathin polyimide substrate with high power density.

The design and functionality of extremely flexible, foldable, and rollable microsupercapacitors (MSCs) with in-plane interdigital electrodes that consist of single-walled carbon nanotube (SWCNT) networks on an ultrathin polyimide substrate are demonstrated through experiments and finite element simulations. The all-solid-state MSCs can be reversibly bent, folded, and rolled purely elastically without degradation of their electrical performance. The simulation results confirm that the deformation in bent, folded, and rolled MSCs is purely elastic. The high power density (1125 W cm-3) and small time constant (1 ms) of the present MSCs are comparable to those of aluminum electrolytic capacitors. The MSCs operate at scan rates of up to 1000 V s-1, are characterized by a volumetric capacitance of 18 F cm-3 and an energy density of 1.6 mWh cm-3, and exhibit superior electrochemical stability with 96% capacity retention even after 100,000 charge/discharge cycles. The developed MSCs demonstrate high potential for integration in flexible and wearable electronic systems

The structural basis of Erwinia rhapontici isomaltulose synthase.

Sucrose isomerase NX-5 from Erwiniarhapontici efficiently catalyzes the isomerization of sucrose to isomaltulose (main product) and trehalulose (by-product). To investigate the molecular mechanism controlling sucrose isomer formation, we determined the crystal structures of native NX-5 and its mutant complexes E295Q/sucrose and D241A/glucose at 1.70 Å, 1.70 Å and 2.00 Å, respectively. The overall structure and active site architecture of NX-5 resemble those of other reported sucrose isomerases. Strikingly, the substrate binding mode of NX-5 is also similar to that of trehalulose synthase from Pseudomonasmesoacidophila MX-45 (MutB). Detailed structural analysis revealed the catalytic RXDRX motif and the adjacent 10-residue loop of NX-5 and isomaltulose synthase PalI from Klebsiella sp. LX3 adopt a distinct orientation from those of trehalulose synthases. Mutations of the loop region of NX-5 resulted in significant changes of the product ratio between isomaltulose and trehalulose. The molecular dynamics simulation data supported the product specificity of NX-5 towards isomaltulose and the role of the loop(330-339) in NX-5 catalysis. This work should prove useful for the engineering of sucrose isomerase for industrial carbohydrate biotransformations