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This paper presents the concept of creating virtual joints in soft robotic structures by modifying the local curvature of non-stretchable thin-walled structures through shape memory alloy (SMA)-based surface actuation. A thin planar flexible material can be stiffened by curving it along one axis, which increases stiffness by increasing the effective thickness. Locally deforming the curved sheet by making a flat region reduces this thickness, creating a defect. The material buckles and bends in a controlled manner at that location under an external force, producing a virtual compliant joint. We use tailored wire placement techniques to embed a continuous SMA wire in a serpentine pattern into denim cloth stiffened by a thin plastic film. When curved, joints can be created in this structure by activating small segments of the SMA wire using Joule heating which induces local curvature, with each of these segments able to exert up to 1.6 N of force. Finally, we present a circuit and algorithm for routing current through any desired SMA wire segment(s). Experimental results show that compliant joints can be created anywhere along the structure, resulting in a reconfigurable system. 

Abstract Aims This study assessed the use of high-energy, visible light on the survival rates of three bacteria commonly found in middle ear infections (i.e. otitis media; Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae). Method and Results Bacteria were cultured and then subjected to a single, 4-h treatment of 405 nm wavelength light at two different intensities. All three bacteria species were susceptible to the light at clinically significant rates (>99.9% reduction). Bacteria were susceptible to the high-energy visible (HEV) light in a dose-dependent manner (lower survival rates with increased intensity and duration of exposure). Conclusions The results suggest that HEV light may provide a non-surgical, non-pharmaceutical approach to the therapeutic treatment of otitis media. Significance an Impact of the Study Given the growing concerns surrounding antibiotic resistance, this study demonstrates a rapid, alternative method for effective inactivation of bacterial pathogens partly responsible for instances of otitis media. 

The sAFAM is a novel mm-size microrobot built using MicroElectroMechanical Systems (MEMS) technology. It consists of a monolithically fabricated microrobotic arm assembled onto four in-plane actuators, capable of moving along four degrees of freedom, including translational movement in X and Y axes as well as pitch and yaw. In this paper, several design modifications were proposed to increase movement precision, stability, and controllability to the sAFAM tip. An interface is developed to assist a human operator accurately position the microrobot tip during nano-object handling. A Python-based graphical user interface (GUI) was programmed to make it intuitive for an operator to use and obtain required tip precision under a microscope. Experimental results demonstrate the functionality of the proposed control solution, and the tip motion resolution using microscope images of the microrobot tip under 20x magnification during operation. The hardware and software requirements for the proposed experimental setup and control platform are discussed in detail. 

The objective of this paper is to demonstrate the flexure properties of ABS plastic in a 3D printed object as a process to enable embedded pressure sensing capabilities. Developing the potential for non-static 3D parts broadens the scope of the fused deposition modeling (FDM) process to include printing ‘smart’ objects that utilize intrinsic material properties to act as microphones, load sensors, accelerometers, etc. In order to demonstrate a strain-based pressure transducer, strain gauges were embedded either directly on top or in the middle of a flexible ABS diaphragm. Securing a strain gage directly on top of the diaphragm traced a reference pressure more closely than diaphragms with the strain gage embedded halfway into the diaphragm. To prevent temperature-related drift, an additional strain gage was suspended above the secured gage, inside the 3D printed cavity. The additional gage allowed for a half-bridge circuit in lieu of a quarter-bridge circuit, which minimized drift due to temperature change. The ABS diaphragm showed no significant signs of elastic hysteresis or nonlinear buckling. When sealed with 100% acetone, the diaphragm leaked ∼50x slower than as-printed sensors. After pressurizing and depressurizing the devices multiple times, they output pressure readouts that were consistent and repeatable for any given pressure within the operational range of 0 to 7psi. The repeatability of each of the final generation sensors indicates that ‘smart’ objects printed using an FDM process could be individually calibrated to make repeatable recordings. This work demonstrates a concept overlooked previous to now — FDM printed objects are not limited to static models, which lack dynamic motion of the part as an element of design. Altering FDM’s bottom-up process can allow for easily embedding sensing elements that result in printed objects which are functional on the mesoscale. 

Abstract Whether an ecological community is controlled from above or below remains a popular framework that continues generating interesting research questions and takes on especially important meaning in agroecosystems. We describe the regulation from above of three coffee herbivores, a leaf herbivore (the green coffee scale, Coccus viridis), a seed predator (the coffee berry borer, Hypothenemus hampei), and a plant pathogen (the coffee rust disease, caused by Hemelia vastatrix) by various natural enemies, emphasizing the remarkable complexity involved. We emphasize the intersection of this classical question of ecology with the burgeoning field of complex systems, including references to chaos, critical transitions, hysteresis, basin or boundary collision, and spatial self-organization, all aimed at the applied question of pest control in the coffee agroecosystem.