Towards enduring autonomous robots via embodied energy.

Autonomous robots comprise actuation, energy, sensory and control systems built from materials and structures that are not necessarily designed and integrated for multifunctionality. Yet, animals and other organisms that robots strive to emulate contain highly sophisticated and interconnected systems at all organizational levels, which allow multiple functions to be performed simultaneously. Herein, we examine how system integration and multifunctionality in nature inspires a new paradigm for autonomous robots that we call Embodied Energy. Whereas most untethered robots use batteries to store energy and power their operation, recent advancements in energy-storage techniques enable chemical or electrical energy sources to be embodied directly within the structures and materials used to create robots, rather than requiring separate battery packs. This perspective highlights emerging examples of Embodied Energy in the context of developing autonomous robots

Laser writing of electronic circuitry in thin film molybdenum disulfide: A transformative manufacturing approach

Electronic circuits, the backbone of modern electronic devices, require precise integration of conducting, insulating, and semiconducting materials in two- and three-dimensional space to control the flow of electric current. Alternative strategies to pattern these materials outside of a cleanroom environment, such as additive manufacturing, have enabled rapid prototyping and eliminated design constraints imposed by traditional fabrication. In this work, a transformative manufacturing approach using laser processing is implemented to directly realize conducting, insulating, and semiconducting phases within an amorphous molybdenum disulfide thin film precursor. This is achieved by varying the incident visible (514 nm) laser intensity and raster-scanning the thin film a-MoS2 sample (900 nm thick) at different speeds for micro-scale control of the crystallization and reaction kinetics. The overall result is the transformation of select regions of the a-MoS2 film into MoO2, MoO3, and 2H-MoS2 phases, exhibiting conducting, insulating, and semiconducting properties, respectively. A mechanism for this precursor transformation based on crystallization and oxidation is developed using a thermal model paired with a description of the reaction kinetics. Finally, by engineering the architecture of the three crystalline phases, electrical devices such as a resistor, capacitor, and chemical sensor were laser-written directly within the precursor film, representing an entirely transformative manufacturing approach for the fabrication of electronic circuitry

Synchronicity in Composite Hydrogels: Belousov–Zhabotinsky (BZ) Active Nodes in Gelatin

Synchronization of motion, task, or communication is responsible for the successful function of many living systems. Composite Belousov–Zhabotinsky (BZ) self-oscillating hydrogels exhibit a sufficiently complex chemical-mechanical feedback to develop synchrony and other dynamical behaviors. In the context of BZ gels, synchrony is the sustained, oscillating oxidation with constant phase of two or more catalyst-immobilized gel segments. However, design criteria to control chemical-mechanical synchronization through patterning of the reaction catalyst are lacking. To characterize the fundamental units of composite device design, the periodic oxidation behavior of isolated nodes, node pairs, and multinode systems were investigated. Isolated nodes of Ru-immobilized gelatin exhibited three distinct, volume-dependent, regimes of oscillation: (i) long period (10–40 min), (ii) biperiod (mix of long and short), and (iii) short period (2.5 min). Node pairs and multinode grids of Ru gelatin were embedded in plain gelatin through a film stacking or 3D printing technique. The fraction of synchronized node pairs decreased with increasing interspace distance. Embedment increased the probability of synchronization, with 100% synchronization for interspace distances of less than 10 times the characteristic length of the reaction–diffusion process. The phase difference between synchronized node pairs transitioned from in-phase at small interspace distances to antiphase at large distances, providing the first experimental verification of antiphase synchrony in composite BZ gels. From these design criteria and fabrication techniques, the chemical-mechanical feedback of BZ composites can be programmed through strategic patterning of the catalyst to build BZ devices for sensor, trigger, or chemical computing applications

Serotonin Potentiates Transforming Growth Factor-beta3 Induced Biomechanical Remodeling in Avian Embryonic Atrioventricular Valves

<div><p>Embryonic heart valve primordia (cushions) maintain unidirectional blood flow during development despite an increasingly demanding mechanical environment. Recent studies demonstrate that atrioventricular (AV) cushions stiffen over gestation, but the molecular mechanisms of this process are unknown. Transforming growth factor-beta (TGFβ) and serotonin (5-HT) signaling modulate tissue biomechanics of postnatal valves, but less is known of their role in the biomechanical remodeling of embryonic valves. In this study, we demonstrate that exogenous TGFβ3 increases AV cushion biomechanical stiffness and residual stress, but paradoxically reduces matrix compaction. We then show that TGFβ3 induces contractile gene expression (RhoA, aSMA) and extracellular matrix expression (col1α2) in cushion mesenchyme, while simultaneously stimulating a two-fold increase in proliferation. Local compaction increased due to an elevated contractile phenotype, but global compaction appeared reduced due to proliferation and ECM synthesis. Blockade of TGFβ type I receptors via SB431542 inhibited the TGFβ3 effects. We next showed that exogenous 5-HT does not influence cushion stiffness by itself, but synergistically increases cushion stiffness with TGFβ3 co-treatment. 5-HT increased TGFβ3 gene expression and also potentiated TGFβ3 induced gene expression in a dose-dependent manner. Blockade of the 5HT2b receptor, but not 5-HT2a receptor or serotonin transporter (SERT), resulted in complete cessation of TGFβ3 induced mechanical strengthening. Finally, systemic 5-HT administration <em>in ovo</em> induced cushion remodeling related defects, including thinned/atretic AV valves, ventricular septal defects, and outflow rotation defects. Elevated 5-HT <em>in ovo</em> resulted in elevated remodeling gene expression and increased TGFβ signaling activity, supporting our <em>ex-vivo</em> findings. Collectively, these results highlight TGFβ/5-HT signaling as a potent mechanism for control of biomechanical remodeling of AV cushions during development.</p> </div

Exogenous 5-HT increases AV cushion stiffness and TGFβ related remodeling genes <i>in ovo</i>.

<p><b>A</b>) The strain energy density (Pa) of HH25 cushions increased 1.4 fold with systemic 5-HT treatment <i>in ovo</i>, mean ± SEM, n = 8–10 cushion, *p<0.05, t-test. <b>B</b>) Gene expression levels of HH25 AV cushions isolated from embryos treated with 5-HT at HH17 (48 hours). mean ± SEM, n = 6–10 samples, each of 8–10 pooled HH25 cushions, *p<0.05, t-test.</p

Remodeling behavior of TGFβ3 treated cushions is a balance of contractile differentiation, proliferation, and matrix synthesis.

<p><b>A</b>) 24 hour TGFβ3 treated cushions upregulate contractile (αSMA, RhoA), proliferation (cyclin b), and extracellular matrix protein (col1α2) encoding genes. TGFβ3 administration also significantly stimulated its own production. mean ± SEM, n = 3–4 pooled samples of 8–10 cushions, *p<0.05, t-test. <b>B</b>) BrdU incorporation data (red) of TGFβ3 treated cushions normalized to DRAQ5 cell nuclei counter stain (blue). BrdU was administered 6 hours prior to completion of 24 hour treatment. Representative confocal images are shown above each bar, with a global view of cushion contained in the inset. mean ± SEM, n = 12, *p<0.0001, t-test.</p