Haojian Lu

Vision-based Nano Robotic System for High-throughput Non-embedded Cell Cutting

Cell cutting is a significant task in biology study, but the highly productive non-embedded cell cutting is still a big challenge for current techniques. This paper proposes a vision-based nano robotic system and then realizes automatic non-embedded cell cutting with this system. First, the nano robotic system is developed and integrated with a nanoknife inside an environmental scanning electron microscopy (ESEM). Then, the positions of the nanoknife and the single cell are recognized, and the distance between them is calculated dynamically based on image processing. To guarantee the positioning accuracy and the working efficiency, we propose a distance-regulated speed adapting strategy, in which the moving speed is adjusted intelligently based on the distance between the nanoknife and the target cell. The results indicate that the automatic non-embedded cutting is able to be achieved within 1–2 mins with low invasion benefiting from the high precise nanorobot system and the sharp edge of nanoknife. This research paves a way for the high-throughput cell cutting at cell’s natural condition, which is expected to make significant impact on the biology studies, especially for the in-situ analysis at cellular and subcellular scale, such as cell interaction investigation, neural signal transduction and low invasive cell surgery.

MORPHOLOGY AND MICROSTRUCTURE OF BATIO3/SRTIO3 SUPERLATTICES GROWN ON SRTIO3 BY LASER MOLECULAR-BEAM EPITAXY

The morphology and microstructure of BaTiO3/SrTiO3 (BTO/STO) superlattices grown epitaxially on STO (001) substrates by a computer-controlled laser molecular-beam epitaxy deposition system have been characterized by means of atomic force microscopy and high-resolution transmission electron microscopy (HRTEM). It is found that the HRTEM images taken along the [120] direction of BTO and STO show the maximal contrast difference. It is, therefore, observed that the superlattices consist of a highly oriented and single-crystalline multilayered structure. As identified by HRTEM, the number of unit cells in each BTO or STO layer matches very well with that obtained from reflection high-energy electron diffraction oscillations. The surfaces and interfaces of the superlattices are atomically smooth. In the superlattices, the ratio between the c axis of BTO and STO is about 4% larger than that measured from BTO or STO bulk crystals.

Multidirectional Image Sensing for Microscopy Based on a Rotatable Robot

Image sensing at a small scale is essentially important in many fields, including microsample observation, defect inspection, material characterization and so on. However, nowadays, multi-directional micro object imaging is still very challenging due to the limited field of view (FOV) of microscopes. This paper reports a novel approach for multi-directional image sensing in microscopes by developing a rotatable robot. First, a robot with endless rotation ability is designed and integrated with the microscope. Then, the micro object is aligned to the rotation axis of the robot automatically based on the proposed forward-backward alignment strategy. After that, multi-directional images of the sample can be obtained by rotating the robot within one revolution under the microscope. To demonstrate the versatility of this approach, we view various types of micro samples from multiple directions in both optical microscopy and scanning electron microscopy, and panoramic images of the samples are processed as well. The proposed method paves a new way for the microscopy image sensing, and we believe it could have significant impact in many fields, especially for sample detection, manipulation and characterization at a small scale.

Automatic Sample Alignment Under Microscopy for 360° Imaging Based on the Nanorobotic Manipulation System

Microscopy has been an indispensable tool for micro/nanosample imaging, manipulation, and characterization. However, viewing the micro/nanosample from multidirection is still a big challenge for current microscopy. To address the above issue, this paper proposes a novel nanorobotic manipulation system for the automatic alignment and multidirectional imaging under microscopes. First, a miniature rotation robot with three degrees of freedom is designed and integrated with a microscope. Then, a forward-backward alignment strategy containing three loops, i.e., position shift loop, angle loop, and magnification loop, is proposed to align the sample to the rotation axis of the robot automatically. After that, the sample is imaged from multidirection by rotating the robot with one revolution (360°). Finally, the alignment accuracy is evaluated and multi-directional images of various samples are implemented. This study provides a new way for the microscopic imaging, which is expected to exert a significant impact in multiple fields on a small scale, including microscopy imaging, microdefect detection, micromanipulation, in situ characterization, and so on.

Nanorobotic System iTRo for Controllable 1D Micro/nano Material Twisting Test

In-situ micro/nano characterization is an indispensable methodology for material research. However, the precise in-situ SEM twisting of 1D material with large range is still challenge for current techniques, mainly due to the testing device’s large size and the misalignment between specimen and the rotation axis. Herein, we propose an in-situ twist test robot (iTRo) to address the above challenges and realize the precise in-situ SEM twisting test for the first time. Firstly, we developed the iTRo and designed a series of control strategies, including assembly error initialization, triple-image alignment (TIA) method for rotation axis alignment, deformation-based contact detection (DCD) method for sample assembly, and switch control for robots cooperation. After that, we chose three typical 1D material, i.e., magnetic microwire Fe74B13Si11C2, glass fiber, and human hair, for twisting test and characterized their properties. The results showed that our approach is able to align the sample to the twisting axis accurately, and it can provide large twisting range, heavy load and high controllability. This work fills the blank of current in-situ mechanical characterization methodologies, which is expected to give significant impact in the fundamental nanomaterial research and practical micro/nano characterization.

Less-invasive non-embedded cell cutting by nanomanipulation and vibrating nanoknife

The less-invasive non-embedded cell cutting or slicing technique provides opportunities for a bio-study at subcellular scale, but there are few effective solutions available at the current stage. This paper reports a robot-aided vibrating system for less-invasive non-embedded cell cutting and investigates the role of key vibrating parameters in the cell cutting process. First, a nanoknife with sharp angle 5° is fabricated from a commercial atomic force microscope cantilever by focused ion beam etching and a vibrating system is constructed from a piezo actuator. Then, they are integrated with a self-developed nanorobotic manipulation system inside an environment scanning electron microscope. After that, we choose yeast cells as the sample to implement the vibrating cutting and investigate the effect of vibrating parameters (frequency and amplitude) on cell cutting quality. The results clearly indicate that the vibrating nanoknife is able to reduce the cutting force and improve the cutting quality. It is al...

Microrobotic Manipulation at Time-Varying Air–Liquid Interface for High-Precise Watch-Hand Alignment

Micromanipulation is a core technique in precise manufacturing and mechatronics. However, current researchers mainly focus on the time-invariant normal environment, whereas complex manipulation at time-varying air–liquid interface is rarely studied, such as the watch-hand alignment problem in industry. To address the above challenge, this paper presents a microrobotic system and corresponding control strategy by modeling the watch-hand movement dynamically at time-varying air–liquid interface. In this paper, a microrobotic manipulation system with five degrees of freedom is developed and integrated with an optical microscopy. Then, the dynamic model of watch-hand is built through Lagrange equation, including the viscoelastic force from glue and the lateral capillary force at the air–liquid interface. After that, a proportional–integral–derivative controller is designed to guarantee the accuracy of the alignment process. Lastly, the accuracy and efficiency of the proposed system is verified through both simulation and experiments. This research provides a common solution for the precise micromanipulation at time-varying air–liquid interface, which would greatly promote the micromanufacturing and microfabrication in lab and industry.

360° multiparametric imaging atomic force microscopy: A method for three-dimensional nanomechanical mapping

Atomic Force Microscopy (AFM) has been intensively used for imaging, characterization and manipulation at the micro- and nanoscale. Taking into account that the material is usually anisotropic, it needs to be characterized in various regions and orientations. Although recent advances of AFM techniques have allowed for large area scan of the sample on a two-dimensional plane, mapping a three-dimensional (3D) sample at a full orientation of 360° remains challenge. This paper reports a multiparametric imaging atomic force microscope via robot technique for 360° mapping and 3D reconstruction of the samples topography and nanomechanical properties. The system is developed by integrating a three degrees of freedom (DoFs) high-precision rotation stage and a home positioning approach is proposed to compensate for the eccentric distance between the cross-section center of the sample and the ration center of the stage. With this method, the sample surface can be fully mapped by the force-distance-based AFM via rotating the sample with a complete orientation. 360° multiparametric mapping and 3D reconstruction results (e.g., topography, adhesion, modulus, energy dissipation) of a human hair demonstrate practicability and reliability of the proposed method.

A bioinspired multilegged soft millirobot that functions in both dry and wet conditions

Developing untethered millirobots that can adapt to harsh environments with high locomotion efficiency is of interest for emerging applications in various industrial and biomedical settings. Despite recent success in exploiting soft materials to impart sophisticated functions which are not available in conventional rigid robotics, it remains challenging to achieve superior performances in both wet and dry conditions. Inspired by the flexible, soft, and elastic leg/foot structures of many living organisms, here we report an untethered soft millirobot decorated with multiple tapered soft feet architecture. Such robot design yields superior adaptivity to various harsh environments with ultrafast locomotion speed (>40 limb length/s), ultra-strong carrying capacity (>100 own weight), and excellent obstacle-crossing ability (stand up 90° and across obstacle >10 body height). Our work represents an important advance in the emerging area of bio-inspired robotics and will find a wide spectrum of applications.Despite the enormous potential of magnetically-guided soft robots for various applications, challenges related to inefficient locomotion in harsh environments hinder its development. Here, the authors demonstrate a multi-legged millirobot with excellent locomotion capability in harsh environments.

Specimen's plane misaligned installation solution based on charge fluctuation inside SEM

Precise specimens installation is a sticking point to ensure the characterization accuracy of the in-situ material property test. Although it is common knowledge that specimens plane misaligned installation (PMI) would cause extra force loading during mechanical testing, there are few effective solutions available to deal with it at the current stage, especially during the in-situ scanning electron microscopy (SEM) test. Taking into consideration the charge fluctuation phenomenon under SEM, this paper proposes a highlight area variation (HAV) method for specimen deformation judgment, i.e., the specimen deformation is defined when the highlight area changes greater than 20% of the initial value of the specimen surface. Three types of specimens with different resistivities, i.e., human hair (electrical resistivity ∼3 × 1012 Ω cm), optical fiber (electrical resistivity ∼1017 Ω cm), and magnetic wire (electrical resistivity ∼2 × 10−5 Ω cm), are chosen to verify the effectiveness of the HAV method. Furthermore, combined with the developed robot-aided alignment system, the specimens PMI problem can also be solved. In the demonstration, the human hair specimen is installed across two specimen stages and its in-situ twisting (in 360°) test is implemented. The results clearly indicate that the HAV method and the robot-aided alignment system are practical and reliable, and the specimen can be aligned on the same plane and installed precisely with accuracy up to 3 μm. This method will benefit the in-situ SEM material mechanical property test and has a significant impact in fundamental material research.Precise specimens installation is a sticking point to ensure the characterization accuracy of the in-situ material property test. Although it is common knowledge that specimens plane misaligned installation (PMI) would cause extra force loading during mechanical testing, there are few effective solutions available to deal with it at the current stage, especially during the in-situ scanning electron microscopy (SEM) test. Taking into consideration the charge fluctuation phenomenon under SEM, this paper proposes a highlight area variation (HAV) method for specimen deformation judgment, i.e., the specimen deformation is defined when the highlight area changes greater than 20% of the initial value of the specimen surface. Three types of specimens with different resistivities, i.e., human hair (electrical resistivity ∼3 × 1012 Ω cm), optical fiber (electrical resistivity ∼1017 Ω cm), and magnetic wire (electrical resistivity ∼2 × 10−5 Ω cm), are chosen to verify the effectiveness of the HAV method. Furthermo...