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The compliance of continuum robot poses difficulty in designing the controller, as the robot does not have position encoder and could be subject to uncertain external force (UEF). The former can be resolved through external sensors, while the latter issue still needs further investigation. This article presents a novel robot design that embeds eGaIn sensors into the soft material, and the elongation in the robot chamber can lead to different changes in resistance values. The sensors act as a proprioceptive mechanism to sense the presence of the UEF. To locate the UEF, the robot surface is divided into multiple regions, and the column and row positions with the force can be solved using Hidden Markov Model and regularization algorithm. Through the virtual work principle, the force magnitude can be also evaluated. Experimental results confirm that, with possible four columns and five rows, the accuracy of finding the actual column and row positions are, respectively, $ 97\%$ and $ 98.5\%$. The mean error in evaluating the tip position and the force magnitude is about $ \text{4}\;\text{mm}$ and $ \text{0.23}\;\text{N}$. This article offers a new approach to obtain the information of the UEF, allowing continuum robots to work in a constrained environment. [ABSTRACT FROM AUTHOR]

Soft-bodied robotic manipulators have great potential for use in minimally invasive surgery, owing to their advantages of high flexibility with infinite degrees of freedom (DOF). One of the potential applications is to perform blood suctioning, which is inevitable during the surgery. To attain higher efficiency in suctioning, the robotic tip should remain vertical while moving along on the work surface. Motivated by this application, this article presents a novel soft robot design and its control scheme to properly configure the tip of a two-segment soft robot while following a planned trajectory on the work surface. Aiming to reduce the incision size and the possibility of infection, a 3D-printed soft-bodied manipulator utilizing the cable-driven mechanism with a diameter of 9 mm was designed and fabricated. An additional DOF was added through a motorized insertion stage. The robot system was modeled using piecewise constant-curvature assumption, and an RGB-D vision was employed to enhance the accuracy of the kinematic-based controller. Performances of the tip positioning and verticalizing were evaluated via simulation, and further verified through experiments. The results confirm that the manipulator is capable of following different trajectories at various velocities while keeping its tip vertical. Compared to other similar works, our results are satisfactory with an root-mean-square error of trajectory tracking within 7 mm, and a maximum angular deviation of 6 $^\circ$. Fluid suction experiments were conducted to demonstrate its effectiveness for automated 3-D suction. This article offers a new tool to support the surgeons for surgical blood suction. [ABSTRACT FROM AUTHOR]

In this study, a system of automatic microparticle patterning that could enable the separation, trapping, and translation of single microbeads in liquid suspension using negative dielectrophoresis (DEP) tweezers was presented to form a single-bead pattern. A microchip with integrated electrodes was flipped and placed above the substrate through a micromanipulator. Microparticles laying on the substrate could be displaced to different positions relative to the electrodes on the microchip, and only the selected particles would be trapped by the electric fields generated from electrodes. Vision-based approaches were used to evaluate the necessary information, such as the gap distance and the positions of electrodes and microparticles in the image. A strategy for separating nearby particles was proposed to achieve single-bead patterning with high accuracy. A controller was used to guide the microparticles toward the position for trapping while avoiding flow disturbance. Different strategies were simulated to decrease the patterning time and find the minimum traveling distance and the best route of movement. The optimization problem is NP-hard. Hence, global optimization algorithms, such as genetic algorithm, particle swarm optimization, and ant colony optimization (ACO), were simulated, and the results were compared with those of the local optimization method. The comparison results showed that ACO obtained the best performance among the methods. The strategy for constructing high-quality microparticle patterns was also examined through experiments. Orange fluorescent polystyrene beads suspended in 6-aminohexanoic acid solution were considered and successfully patterned on a glass substrate by using the proposed system. Note to Practitioners—Micropatterning is an effective tool for pharmaceutical research and drug discovery. However, the reliability of results depends on the quality of patterns. Existing approaches, such as microfluidic devices, are limited to create a pattern from one chip for single use, and the entire process is sealed and isolated from the environment. In this study, a multielectrode microchip combined with a vision-based micromanipulator is introduced to create a novel noncontact approach for microparticle patterning, which offers high flexibility and guarantees the quality of the constructed patterns. The electrodes on the chip can be selectively energized to determine the shape of the final pattern. A real-time screening is performed so that the micromanipulator will only guide the particles in good condition for selection. An optimization algorithm is implemented to aid the particle selection with the electrodes, allowing high-quality microparticle patterns to be constructed in a short time for various applications. [ABSTRACT FROM AUTHOR]

A soft-bodied robot exhibits prominent dexterity due to the soft nature of its material. However, the softness can become a burden when the robot needs to interact with the environment, given that the targeted object is usually much stiffer than the compliant soft robot. A variable-stiffness soft robot, fusing the merits of softness and stiffness, is in favor of many applications, such as robot-assisted minimally invasive surgeries. In this article, we propose a tendon-tensioning method to adaptively control the stiffness of a dual-segment tendon-driven backboneless soft robot based on depth vision. A depth-vision-based closed-loop controller is designed for stiffness compensation when the manipulator is subjected to the external load. Experiments were conducted to examine the feasibility and performance of the proposed method. The results confirm our control scheme on the robot with controllability of stiffness up to 132%. Based on our method, the manipulator with an external payload can follow designated trajectories with positioning errors reduced up to 50% comparing to that with open-loop control. Without quantifying the instantaneous stiffness, this work contributes a generalized method for tuning the stiffness of the tendon-driven soft robots in the presence of external disturbances without onboard sensing. [ABSTRACT FROM AUTHOR]

Embryo manipulation is a fundamental task in assisted reproductive technology (ART). Nevertheless, conventional pick-place techniques often require proper alignment to avoid causing damage to the embryo and further, the tools have limited capability to orient the embryo being handled. Objective: This paper presents a novel and non-invasive technique that can easily manipulate mouse embryos on a polyvinyl chloride (PVC) Petri dish. Methods: An inverted microchip with quadrupole electrodes was attached to a micromanipulator to become a robotic dielectrophoresis (DEP) tweezers, and a motorized platform provided additional mobility to the embryos lying on a Petri dish. Vision-based algorithms were developed to evaluate relevant information of the embryos from the image, and to provide feedback signals for precise position and orientation control of the embryo. Results: A series of experiments was conducted to examine the system performance, and the embryo can be successfully manipulated to a specified location with the desired orientation for subsequent processing. Conclusion: This system offers a non-contact, low cost, and flexible method for rapid cell handling. Significance: As the DEP tweezers can grasp the embryo without the need for precise alignment, the overall time required to process a large number of embryos can be shortened. [ABSTRACT FROM AUTHOR]

In robot-assisted surgery (RAS), three-dimensional (3-D) position estimation of a surgical suture thread is essential in automating the wound suturing procedure. Nevertheless, accurate suture thread’s segmentation and its 3-D coordinates reconstruction remain challenging because of its flexible property and lacking indistinctive feature points. In this paper, a novel model-free method is proposed to enable the 3-D computation of a suture thread through a calibrated stereo camera system. In this method, only the suture thread’s tip and grasping points need to be indicated on one image with mouse clicks, and their accurate image positions can be detected using computed contour information. Afterward, key points that represent the suture thread are generated on one image, while their matched points on the second camera frame are evaluated through an iterative algorithm for 3-D model reconstruction. Experiments using different backgrounds and environmental conditions were conducted to examine the accuracy and robustness of the 2-D segmentation. The suture threads were then formed in various 3-D shapes, and their respective 3-D models were reconstructed for comparison. The experimental results confirm the feasibility of our method in reducing human intervention in the detection of matched key points on an image pair, thereby guaranteeing an accurate 3-D coordinates computation of a suture thread. [ABSTRACT FROM AUTHOR]

Seeding cells on a planar substrate is the first step to construct artificial tissues in vitro. Cells should be organized into a pattern similar to native tissues and cultured on a favorable substrate to facilitate desirable tissue ingrowth. In this study, a microchip system is designed and fabricated to form cells into a specific pattern on different substrates. The system consists of a microchip with a dot-electrode array for cell trapping and patterning and two motorized platforms for providing relative motions between the microchip and the substrate. AC voltage is supplied to the selected electrodes by using a programmable micro control unit to control relays connected to the dot-electrodes. Nonuniform electric fields for cell manipulation are formed via negative dielectrophoresis (n-DEP). Experiments were conducted to create different patterns by using yeast cells. The effects of different experimental parameters and material properties on the patterning efficiency were evaluated and analyzed. Mechanisms to remove abundant cells surrounding the constructed patterns were also examined. Results show that the microchip system could successfully create cell patterns on different substrates. The use of calcium chloride (CaCl $_2$) enhanced the cell adhesiveness on the substrate. The proposed n-DEP patterning technique offers a new method for constructing artificial tissues with high flexibility on cell patterning and selecting substrate to suit application needs. [ABSTRACT FROM AUTHOR]