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This paper presents a novel piezoelectric-actuated microgripper that mainly consists of a three-stage flexure-based amplification mechanism to achieve a large magnification ratio, a high structural stiffness 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 (FEM)-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 30.66 with a maximum clamping force of up to 2.32N. The gripper prototype has been fabricated based on the wire electro discharge machining technique, and its performances have been validated through pack-and-place of microbeads experiments. The experimental results have demonstrated its excellent linear amplification performance and they match well with the outcomes from both simulation and theoretical calculation in terms of motion range and amplification ratio.

The near-field enhancement underneath the AFM tip irradiated by a laser beam is widely utilized in various nanofabrication techniques, such as nano-welding, nano-manipulation, nano-etching and so on. In this paper, a numerical model of near-field enhancement on AFM tip irradiated by annular laser beam is established using COMSOL Multiphysics. The results show that when the AFM tip is irradiated by annular laser beam, strong near-field enhancement is induced at the apex of the tip. The field distribution curve with the substrate presents a saddle shape, which demonstrates that the annular beam irradiated the AFM tip produce an extremely high near-field enhancement between the particle and the tip. In addition, the results indicate that when the AFM tip is irradiated by the annular laser with higher frequency, the near-field enhancement underneath the apex of the tip increases correspondingly. Moreover, when the irradiation angle is 60 Deg and the irradiation distance is 65 nm, the near-field enhancement reaches the peak. Based on the numerical simulation of the near-field enhancement, the system of the AFM tip irradiated by annular laser beam can be anticipated for further application in the field of nanofabrication.

With the rapid growth of multimedia data (e.g., image, audio and video etc.) on the web, learning-based hashing techniques such as Deep Supervised Hashing (DSH) have proven to be very efficient for large-scale multimedia search. The recent successes seen in Learning-based hashing methods are largely due to the success of deep learning-based hashing methods. However, there are some limitations to previous learning-based hashing methods (e.g., the learned hash codes containing repetitive and highly correlated information). In this paper, we propose a novel learning-based hashing method, named Deep Attention-guided Hashing (DAgH). DAgH is implemented using two stream frameworks. The core idea is to use guided hash codes which are generated by the hashing network of the first stream framework (called first hashing network) to guide the training of the hashing network of the second stream framework (called second hashing network). Specifically, in the first network, it leverages an attention network and hashing network to generate the attention-guided hash codes from the original images. The loss function we propose contains two components: the semantic loss and the attention loss. The attention loss is used to punish the attention network to obtain the salient region from pairs of images; in the second network, these attention-guided hash codes are used to guide the training of the second hashing network (i.e., these codes are treated as supervised labels to train the second network). By doing this, DAgH can make full use of the most critical information contained in images to guide the second hashing network in order to learn efficient hash codes in a true end-to-end fashion. Results from our experiments demonstrate that DAgH can generate high quality hash codes and it outperforms current state-of-the-art methods on three benchmark datasets, CIFAR-10, NUS-WIDE, and ImageNet., Comment: Accepted to IEEE ACCESS

Images with resolution beyond the diffraction limit (superresolution) were obtained by combining conventional microscopy with microscale microsphere, which provides a new possibility for real-time optical superresolution imaging. Here, we propose a method to manipulate the microsphere by attaching it to a probe with optical glue. The optical simulation has been performed to demonstrate the influence of probe on superresolution image. The probe was fixed on a translation stage which was regarded as a robotic manipulator with four degrees of freedom. The kinematic analysis of the robotic manipulator was studied for manipulation strategy of microsphere. The force analysis has been carried out to analyze the possibility of microsphere detach from probe. To improve imaging quality, the microsphere was immersed in liquid medium and the resolution of 130 nm (∼λ/4.5) was achieved. In addition, by scanning the microsphere at the speed of 5 μm/s over the sample surface and stitching the recorded images, the superresolution image of large continuous area was achieved. This work had important practical significance for manipulating microsphere and optical superresolution imaging.

Catalytic micro- and nanorobots exhibit self-propulsion in the presence of chemical fuels such as glucose, hydrogen peroxide. Generally, swimmers incorporate a catalyst as a part of their structure for the decomposition of a chemical fuel. Several applications such as active drug delivery, minimally invasive surgery, and water remediation, have been envisaged. In this letter, we investigated the influence of geometric variable of catalytic microrobot to their swimming behaviors in hydrogen peroxide (H2O2) solutions. V-shaped microrobots with various opening angles (45°, 90°, and 135°), and triangle-shaped microrobots that have similar dimensions with V-shaped microrobots, have been fabricated by focused-ion-beam etching on commercial platinum microwires. Swimming tests were performed in 15% and 30% H2O2 solutions. We have found that V-shaped microrobot with 45° opening angle showed a superior swimming speed of 4.3 μm/s in 15% H2O 2 solution, while 90° microrobot exhibits a speed of 1.52 μm/s. The 135° V-shaped microrobot and all triangle-shaped microrobots have not shown any obvious motions in 30% H2O2 solution. Our observation that the swimming performances of various shaped microrobots change in tandem proves the necessity of structural asymmetry in designing catalytic micro- and nanorobots.

Due to the coaction of supply harmonics and the harmonics resulting from the motor structures, the mechanism and distribution characteristics of iron losses become more complicated in inverter-fed induction motors. Therefore, accurate prediction and fine analysis of iron loss are very important at the design stage of high-efficiency inverter-fed induction motors. In order to predict the iron losses accurately, this paper proposes a piecewise iron loss model whose parameters vary with the magnitude and frequency of flux density, and two additional flux density terms are introduced to the classical iron loss model considering the nonlinearity of magnetic material and harmonic fields. With this model, the iron losses are calculated for an inverter-fed 5.5 kW induction motor. The results reveal the distribution characteristics of hysteresis and eddy current losses in stator and rotor cores, and the characteristics of additional iron loss caused by harmonic fields. By the comparison of predicted and measured no-load iron loss under different supply voltages and switching frequencies, the proposed model and the analysis results are validated.

Energy harvesting technique has been identified as an innovative and environment-friendly way for powering micro sensors and electronic devices. In this paper, a hybrid generator based on triboelectric and electromagnetic mechanisms (TMHG), which provides two electrical power outputs at the same time, was proposed. The output performance in time and frequency domains are investigated at different initial gap distances and excitation accelerations. At an acceleration of 1 g and an initial gap distance of 5 mm, the maximum power outputs of electromagnetic and triboelectric parts can be obtained as 0.28 mW and 1.09 mW, respectively. The resonant frequency of the TMHG is as low as 23.5 Hz, making it more suitable to harvest energy from low frequency vibrations of less than 30 Hz. Besides, the operating bandwidth of TMHG can be adjusted by changing the initial gap distance according to the application requirements.

Non-skewed rotors can be used to eliminate the slot harmonic field, as well as, the noise and vibration can also be weakened effectively. However, it is difficult to determine the spatial distribution of the asymmetrical rotor bars and slot combinations, which can affect the loss and air-gap force significantly. Taking a 5.5kW, 4-pole induction motor as an example, this paper studies the influence of the above factors on the loss and air-gap force systematically, by using Finite Element Method (FEM), and the experiment validation on efficiency and no-load noise are also performed on a 5.5 kW prototype.

The ability to pick up a single carbon nanotube (CNT) from a bundle of CNTs is of great importance for nanodevice fabrication. In this study, we propose a nanorobotic manipulation system allowing automated pick-up of CNTs based on visual feedback. We used histogram thresholding for automatic binarization, and it clearly distinguished CNTs from the substrate and other impurities under various image brightnesses and contrasts. Furthermore, the CNT tip was successfully extracted by making use of the geometrical characteristics of the CNT. We designed a segment detection method to separate the CNT and atomic force microscope cantilever during overlapping. The contact detection between them was identified by evaluating the linearity of the fitted CNT curve. We also further analyzed the specific properties of point contact and linear contact, significantly improving the success rate of pick-up. Finally, the experimental results show that our method is highly promising for realistic fabrication of nanodevices.

This paper introduces a novel catalytic mobile micro/nanorobot made only of platinum that realizes nanometer locomotion in hydrogen peroxide solution. The innovative mechanism and principle of the nanorobot are presented. A simple and effective fabrication process by focused ion beam and a stable manipulation method of the nanorobot are demonstrated. The nanorobot can steer or navigate by its finely designed geometry, and keep a stable rotational motion rather than arbitrary and uncertain movement. This paper evaluates the influence of some critical factors on the movement of the nanorobot, such as the concentration and temperature of the hydrogen peroxide solution, and the geometry of a nanorobot. The control of the nanorobot's movement can be realized based on the result of this evaluation. Compared with previous studies, this catalytic platinum nanorobot realizes bidirectional rather than unidirectional movement. The Langevin equation is used to describe the dynamic model of the platinum nanorobot.