Bioinspired design and optimization for thin film wearable and building cooling systems.

In this work, we report a paradigmatic shift in bioinspired microchannel heat exchanger design toward its integration into thin film wearable devices, thermally active surfaces in buildings, photovoltaic devices, and other thermoregulating devices whose typical cooling fluxes are below 1 kW m. The transparent thermoregulation device is fabricated by bonding a thin corrugated elastomeric film to the surface of a substrate to form a microchannel water-circuit with bioinspired unit cell geometry. Inspired by the dynamic scaling of flow systems in nature, we introduce empirically derived sizing rules and a novel numerical optimization method to maximize the thermoregulation performance of the microchannel network by enhancing the uniformity of flow distribution.

Silver-Coated Poly(dimethylsiloxane) Beads for Soft, Stretchable, and Thermally Stable Conductive Elastomer Composites.

We introduce an elastomer composite filled with silver (Ag) flakes and Ag-coated poly(dimethylsiloxane) (PDMS) beads that exhibits electrical conductivity that is 2 orders of magnitude greater than that of elastomers in which the same concentration of Ag filler is uniformly dispersed. In addition to the dramatic enhancement in conductivity, these composites exhibit high mechanical compliance (strain limit, >100%) and robust thermal stability (conductivity change, <10% at 150 °C). The incorporation of Ag-coated PDMS beads introduces an effective phase segregation in which Ag flakes are confined to the "grain boundaries" between the embedded beads.

Chasing biomimetic locomotion speeds: Creating untethered soft robots with shape memory alloy actuators.

By using compliant lightweight actuators with shape memory alloy, we created untethered soft robots that are capable of dynamic locomotion at biologically relevant speeds.

Visually Imperceptible Liquid-Metal Circuits for Transparent, Stretchable Electronics with Direct Laser Writing.

A material architecture and laser-based microfabrication technique is introduced to produce electrically conductive films (sheet resistance = 2.95 Ω sq ; resistivity = 1.77 × 10 Ω m) that are soft, elastic (strain limit >100%), and optically transparent.

A Biologically Inspired, Functionally Graded End Effector for Soft Robotics Applications.

Soft robotic actuators offer many advantages over their rigid counterparts, but they often are unable to apply highly localized point loads. In contrast, many invertebrates have not only evolved extremely strong "hybrid appendages" that are composed of rigid ends that can grasp, puncture, and anchor into solid substrates, but they also are compliant and resilient, owing to the functionally graded architecture that integrates rigid termini with their flexible and highly extensible soft musculatures. Inspired by the design principles of these natural hybrid appendages, we demonstrate a synthetic hybrid end effector for soft-bodied robots that exhibits excellent piercing abilities.

Orientationally correlated colloidal polycrystals without long-range positional order.

We probe the local and global structure of spin-coated colloidal crystals via laser diffraction measurements and scanning electron and atomic force microscopies, and find that they are unique three-dimensional orientationally correlated polycrystals, exhibiting short-range positional order but long-range radial orientational correlations, reminiscent of-but distinct from-two-dimensional colloidal hexatic phases. Thickness and symmetries are controllable by solvent choice and spin speed. While the polycrystallinity of these colloidal films limits their applicability to photonics, we demonstrate their feasibility as templates to make crack-free magnetic patterns.