As an ideal method to manipulate biological particles, the dielectrophoresis (DEP) technique has been widely used in clinical diagnosis, disease treatment, drug development, immunoassays, cell sorting, etc. This review summarizes the research in the field of bioparticle manipulation based on DEP techniques. Firstly, the basic principle of DEP and its classical theories are introduced in brief; Secondly, a detailed introduction on the DEP technique used for bioparticle manipulation is presented, in which the applications are classified into five fields: capturing bioparticles to specific regions, focusing bioparticles in the sample, characterizing biomolecular interaction and detecting microorganism, pairing cells for electrofusion and separating different kinds of bioparticles; Thirdly, the effect of DEP on bioparticle viability is analyzed; Finally, the DEP techniques are summarized and future trends in bioparticle manipulation are suggested.
Magnetic miniature soft robots have shown great potential for facilitating biomedical applications by minimizing invasiveness and possible physical damage. However, researchers have mainly focused on fixed-size robots, with their active locomotion accessible only when the cross-sectional dimension of these confined spaces is comparable to that of the robot. Here, we realize the scale-reconfigurable miniature ferrofluidic robots (SMFRs) based on ferrofluid droplets and propose a series of control strategies for reconfiguring SMFR’s scale and deformation to achieve trans-scale motion control by designing a multiscale magnetic miniature robot actuation (M 3 RA) system. The results showed that SMFRs, varying from centimeters to a few micrometers, leveraged diverse capabilities, such as locomotion in structured environments, deformation to squeeze through gaps, and even reversible scale reconfiguration for navigating sharply variable spaces. A miniature robot system with these capabilities combined is promising to be applied in future wireless medical robots inside confined regions of the human body.
This article proposed a high-performance triboelectric-electromagnetic hybrid wind energy harvester (WEH). By adopting the revolution and rotation movements of tapered rollers, which serve as both the rotor of the electromagnetic generator (EMG) part and freestanding layers of the triboelectric nanogenerator (TENG) part, the WEH can work as a sustainable power source and a self-powered wind speed sensor. When the wind speed is 12 m/s, super-high open-circuit voltage peaks of 47.4 and 683 V can be achieved by the EMG and TENG, respectively, corresponding to the high-power outputs of 62 and 1.8 mW. It was demonstrated that the WEH can easily light up over 600 red light-emitting diodes and even a 5-W globe light. A self-powered wireless temperature and humidity sensing network was also systematically demonstrated. In summary, the proposed WEH exhibits bright future toward IoT applications, such as in border detection, smart buildings, and so on.
Stretchable superhydrophobic materials are of potential interest for next-generation multi-functional haptic technologies particularly suited for wearable device and artificial skin applications. However, the practical applications of stretchable superhydrophobic materials are hindered by some issues, such as low mechanical robustness, harmful chemicals, etc. Here, we partially embedded perfluorosilane-coated graphene into thermoplastic polyurethane (TPU) by a dissolution and resolidification method. Due to the exceptional physical properties of graphene, the resulting nanocomposites could maintain their superhydrophobicity after toleration of strain up to 400%, man-made destruction by hands or sandpapers, pollution by oil, immersion in various corrosive liquids, and heat treatment at 150 °C for 24 h. It should be noted that even under an ultra-large load of 2 kg (32.5 kPa pressure), this graphene composite could withstand the abrasion by sandpaper for 20.00 m without losing superhydrophobicity. More remarkably, the electrical resistance of this graphene superhydrophobic composite is sensitive to material deformation, and can be directly applied to gloves for real-time detection of human motions.
22 January 2021 in IEEE/ASME Transactions on Mechatronics
This article presents a piezoelectric-actuated microgripper that mainly consists of a three-stage flexure-based amplification mechanism to achieve a large magnification ratio with an excellent linearity, a large operating bandwidth, and a great force output capacity for micromanipulation and assembly. The first two stages are configured as two bridge-type parallelogram amplification mechanisms connected in serial to provide advantages in terms of high structural stiffness and compactness. This configuration is capable of generating large forces to maintain the following connection leverage mechanism and ensure a large displacement output, and also produces a stable amplification ratio insensitive to the input change. The finite element method-based simulation has been performed to investigate both static and dynamic characteristics of the designed microgripper. Simulation-enabled structural optimization design has been implemented to further aid and improve the proposed design. The simulation results indicate that the amplification ratio reaches 30.3 with a maximum clamping force of up to 2.17N. The gripper prototype has been fabricated based on the wire electrodischarge machining technique, and its performances have been validated through pick-and-place of microbeads experiments and dynamic tests. The experimental results have demonstrated the large amplification ratio of 31.88 with excellent linearity, and the motion stroke of 218 μm with a large grasping force up to 1993 mN. They well match the results from both simulation and theoretical calculation in terms of motion range and amplification ratio.
In this study, a flexible tactile sensing array based on a capacitive mechanism was designed, fabricated, and characterized for sensitive robot skin. A device with 8 × 8 sensing units was composed of top and bottom flexible polyethyleneterephthalate (PET) substrates with copper (Cu) electrodes, a polydimethylsiloxane (PDMS) dielectric layer, and a bump contact layer. Four types of microstructures (i.e., pyramids and V-shape grooves) atop a PDMS dielectric layer were well-designed and fabricated to enhance tactile sensitivity. The optimal sensing unit achieved a high sensitivity of 35.9%/N in a force range of 0–1 N. By incorporating a tactile feedback control system, the flexible sensing array as the sensitive skin of a robotic manipulator demonstrated a potential capability of robotic obstacle avoidance.