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Abstract Microfluidics has enabled the miniaturization of fluidic systems for various biomedical and industrial applications, including small-scale robotic propulsion. One mechanism for generating propulsive force through microfluidics is by exploiting the solutal Marangoni effect via releasing surfactant on the air-water interface. Surfactants locally reduce the surface tension, which leads to a surface stress that can propel the floating robot, called Marangoni surfer. However, so far the release of the surfactant is not controllable. In this study, we combine microfluidics-based Marangoni propulsion with a novel untethered magnetic pumping mechanism to enhance its controllability. The proposed magnetic micropump capitalizes on the interaction force between two soft magnets, which can generate a pumping force of 4.64 mN to actuate a membrane, and achieve a deformation of 450 μm. Net flow is achieved using a nozzle/diffuser flow rectifier whose efficacy as a function of the channel geometry is numerically studied. We investigate the flow rate of the pump with regard to the actuation frequency. Finally, we demonstrate its ability to control the motion of the Marangoni surfer.

Continuum manipulators have found several applications in surgical interventions like endoscopy, laparoscopy, and as end‐effectors for surgical robots. Continuum manipulators coupled with magnetic actuation can be precisely maneuvered inside the human body. Recently, variable stiffness manipulators (VSMs) have been introduced for enhanced dexterity and safe navigation. This study presents a new design of a magnetically actuated VSM based on shape memory polymer (SMP) springs. The VSM has a silicone backbone enclosed within a spring made of SMP that can change in length with stiffness change that is triggered by Joule heating. The stiffness and thermal characteristics of the VSM are studied using analytical models and experiments. Subsequently, a one‐segment VSM and a two‐segment VSM having outer diameters of 9 and 10 mm and lengths of 15 and 25 mm, respectively, capable of extending to four times their length are designed. The VSM can be deployed in a compact form and extended to achieve variable bending curvatures in soft and rigid states, which can facilitate instrument insertion and reduce operation invasiveness. Potential clinical applications are demonstrated by incorporating miniature camera, biopsy tool, and laser optical fiber in the working channel of the VSM and coupled with robotic magnetic actuation.

The oxoruthenium(V) complexes K(Ru super V-double bond-O EDTA) and K(Ru super V-double bond-O PDTA) were produced from the oxidation by NaOCl in a water-dioxane medium of the chloro complexes K(Ru super III EDTA-H Cl) and K(Ru super III PDTA-H Cl). The chloro complexes are characterized by pentadentate EDTA and PDTA ligands, configuring four chelate rings with Ru-Cl bond distances equal to 2.358(4) Angstrom (A) and 2.393(2) A, respectively. The oxoruthenium(V) complexes, meanwhile, are quite stable in the solid phase and in aqueous solution for at least one week at room temperature.

Abstract Advances in magnetoresponsive composites and (electro‐)magnetic actuators have led to development of magnetic soft machines (MSMs) as building blocks for small‐scale robotic devices. Near‐field MSMs offer energy efficiency and compactness by bringing the field source and effectors in close proximity. Current challenges of near‐field MSM are limited programmability of effector motion, dimensionality, ability to perform collaborative tasks, and structural flexibility. Herein, a new class of near‐field MSMs is demonstrated that combines microscale thickness flexible planar coils with magnetoresponsive polymer effectors. Ultrathin manufacturing and magnetic programming of effectors is used to tailor their response to the nonhomogeneous near‐field distribution on the coil surface. The MSMs are demonstrated to lift, tilt, pull, or grasp in close proximity to each other. These ultrathin (80 µm) and lightweight (100 gm−2) MSMs can operate at high frequency (25 Hz) and low energy consumption (0.5 W), required for the use of MSMs in portable electronics.

This work investigates the stick–slip phenomenon during sliding motion between solid lubricant-impregnated epoxy polymer-coated steel bars and AISI 52,100 steel balls. An acoustic sensor detected the stick–slip phenomenon during the tribo-pair interaction. The wear characteristics of the workpiece coated with different epoxy coatings were observed and scrutinized. The RMS values of the acoustic sensor were correlated with the frictional coefficient to develop a standard based on the acoustic sensor, leading to the detection of the stick–slip phenomenon. As per the findings, the acoustic waveform remained relatively similar to the friction coefficient observed during the study and can be used effectively in detecting the stick–slip phenomenon between steel and polymer interaction. This work will be highly beneficial in industrial and automotive applications with a significant interaction of polymer and steel surfaces.