Yan Liang Zhang

University of Toronto, Toronto, Ontario, Canada

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Publications (11)19.03 Total impact

  • Yan Liang Zhang, Yong Zhang, Changhai Ru, B.K. Chen, Yu Sun
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    ABSTRACT: This paper presents a nanomanipulation system for operation inside scanning electron microscopes (SEM). The system is compact, making it capable of being mounted onto and demounted from an SEM through the specimen-exchange chamber (load-lock) without breaking the high vacuum of the SEM. This advance avoids frequent opening of the high-vacuum chamber, thus, incurs less contamination to the SEM, avoids lengthy pumping, and significantly eases the exchange of end effectors (e.g., nanoprobes and nanogrippers). The system consists of two independent 3-DOF Cartesian nanomanipulators driven by piezomotors and piezoactuators. High-resolution optical encoders are integrated into the nanomanipulators to provide position feedback for closed-loop control. The system is characterized, yielding the encoders' resolution of 2 nm and the piezoactuators' resolution of 0.7 nm. A look-then-move control system and a contact-detection algorithm are implemented for horizontal and vertical nanopositioning.
    IEEE/ASME Transactions on Mechatronics 01/2013; 18(1):230-237. · 3.14 Impact Factor
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    ABSTRACT: Nanowire field-effect transistors (nano-FETs) are nanodevices capable of highly sensitive, label-free sensing of molecules. However, significant variations in sensitivity across devices can result from poor control over device parameters, such as nanowire diameter and the number of electrode-bridging nanowires. This paper presents a fabrication approach that uses wafer-scale nanowire contact printing for throughput and uses automated nanomanipulation for precision control of nanowire number and diameter. The process requires only one photolithography mask. Using nanowire contact printing and post-processing (i.e. nanomanipulation inside a scanning electron microscope), we are able to produce devices all with a single-nanowire and similar diameters at a speed of ~1 min/device with a success rate of 95% (n = 500). This technology represents a seamless integration of wafer-scale microfabrication and automated nanorobotic manipulation for producing nano-FET sensors with consistent response across devices.
    Nanotechnology 02/2012; 23(6):065304. · 3.84 Impact Factor
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    ABSTRACT: This paper presents a microelectromechanical systems (MEMS) device for simultaneous electrical and mechanical characterization of individual nanowires. The device consists of an electrostatic actuator and two capacitive sensors, capable of acquiring all measurement data (force and displacement) electronically without relying on electron microscopy imaging. This capability avoids the effect of electron beam (e-beam) irradiation during nanomaterial testing. The bulk-microfabricated devices perform electrical characterization at different mechanical strain levels. To integrate individual nanowires to the MEMS device for testing, a nanomanipulation procedure is developed to transfer individual nanowires from their growth substrate to the device inside a scanning electron microscope. Silicon nanowires are characterized using the MEMS device for their piezoresistive as well as mechanical properties. It is also experimentally verified that e-beam irradiation can significantly alter the characterization results and must be avoided during testing.
    Journal of Microelectromechanical Systems 09/2011; · 2.13 Impact Factor
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    ABSTRACT: This paper presents a microfluidic system for cell type classification using mechanical and electrical measurements on single cells. Cells are aspirated continuously through a constriction channel with cell elongations and impedance profiles measured simultaneously. The cell transit time through the constriction channel and the impedance amplitude ratio are quantified as cell's mechanical and electrical property indicators. The microfluidic device and measurement system were used to characterize osteoblasts (n=206) and osteocytes (n=217), revealing that osteoblasts, compared with osteocytes, have a larger cell elongation length (64.51 ± 14.98 μm vs. 39.78 ± 7.16 μm), a longer transit time (1.84 ± 1.48 s vs. 0.94 ± 1.07 s), and a higher impedance amplitude ratio (1.198 ± 0.071 vs. 1.099 ± 0.038). Pattern recognition using the neural network was applied to cell type classification, resulting in classification success rates of 69.8% (transit time alone), 85.3% (impedance amplitude ratio alone), and 93.7% (both transit time and impedance amplitude ratio as input to neural network) for osteoblasts and osteocytes. The system was also applied to test EMT6 (n=747) and EMT6/AR1.0 cells (n=770, EMT6 treated by doxorubicin) that have a comparable size distribution (cell elongation length: 51.47 ± 11.33 μm vs. 50.09 ± 9.70 μm). The effects of cell size on transit time and impedance amplitude ratio were investigated. Cell classification success rates were 51.3% (cell elongation alone), 57.5% (transit time alone), 59.6% (impedance amplitude ratio alone), and 70.2% (both transit time and impedance amplitude ratio). These preliminary results suggest that biomechanical and bioelectrical parameters, when used in combination, could provide a higher cell classification success rate than using electrical or mechanical parameter alone.
    Lab on a Chip 08/2011; 11(18):3174-81. · 5.70 Impact Factor
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    ABSTRACT: Making changes of cells function by regulating the external mechanical environment is one of the major interests in the mechanobiology field. Based on extensive studies, force at nano-to-micro newton and geometric shape changes at nano to-micrometer are the physical stimuli that can be sensed by cells. It has been postulated that controllable cell responses can be produced by activating diversity of mechanosesory proteins through physical changes of force or shape. In this paper, a real-time machine vision algorithm is proposed to improve the efficiency and robustness of the cell membranes strain calculation. The proposed adaptive image thresholding method with modified numerical implementation is able to apply on all the images captured in the deforming process to extract the deformed cell boundary in real-time. Based on the proposed method, the cell membrane strain is modeled and controlled to deform the cell into a predefined deformation. It enables biologists to study the biochemical changes within the cell by providing a controllable geometric changes. It also expects that a particular cell status or function could be produced by giving a proper deformation.
    Robotics and Automation (ICRA), 2011 IEEE International Conference on; 06/2011
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    ABSTRACT: This paper presents a nanomanipulation system for operation inside scanning electron microscopes (SEM). The system is small in size, capable of being mounted onto and demounted from an SEM through the specimen exchange chamber without breaking the high vacuum of the SEM. This advance eliminates frequent opening of the high-vacuum chamber, thus, incurs less contamination to the SEM, avoids lengthy pumping, and significantly eases the exchange of end-effectors (e.g., nano probes and grippers). The system consists of two independent 3-DOF Cartesian nanomanipulators based on piezo motors and piezo actuators. High-resolution optical encoders are integrated into the nanomanipulators to provide position feedback for closed-loop control. A look-then-move control system and a contact detection algorithm are implemented for horizontal and vertical nanopositioning. The system design, system characterization details, and system performance are described.
    Robotics and Automation (ICRA), 2011 IEEE International Conference on; 06/2011
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    ABSTRACT: Mechanical force sensing is an important and integral component in the study of the viscoelastic properties of biological cells. In this study, a vision-based non-contact force sensing technique for real-time stressing of biological cells by a vision-guided robotic micromanipulation system is introduced. The system is capable of providing real-time external mechanical stressing on biological cells with a predefined profile and estimating the cell membrane deformation using the proposed cell strain model. One of the phenomena manifesting the viscoelastic properties of cells is the gradual reduction of reaction force in the compressive stress under cyclic loading. The applied force with respect to the cell membrane strain and the number of stressing cycles is modelled and validated by different zebrafish embryos. The experimental results show that the proposed force model can estimate the reaction force of cell membrane with the average maximum error of 10.07%.
    Micro & Nano Letters 06/2011; · 0.85 Impact Factor
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    ABSTRACT: This paper presents a microfluidic device for simultaneous mechanical and electrical characterization of single cells. The device performs two types of cellular characterization (impedance spectroscopy and micropipette aspiration) on a single chip to enable cell electrical and mechanical characterization. To investigate the performance of the device design, electrical and mechanical properties of MC-3T3 osteoblast cells were measured. Based on electrical models, membrane capacitance of MC-3T3 cells was determined to be 3.39±1.23 and 2.99±0.82 pF at the aspiration pressure of 50 and 100 Pa, respectively. Cytoplasm resistance values were 110.1±37.7 kΩ (50 Pa) and 145.2±44.3 kΩ (100 Pa). Aspiration length of cells was found to be 0.813±0.351 μm at 50 Pa and 1.771±0.623 μm at 100 Pa. Quantified Young's modulus values were 377±189 Pa at 50 Pa and 344±156 Pa at 100 Pa. Experimental results demonstrate the device's capability for characterizing both electrical and mechanical properties of single cells.
    Biomicrofluidics 01/2011; 5(1):14113. · 3.39 Impact Factor
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    ABSTRACT: This paper presents a microfluidic device for simultaneous electromechanical characterization of single cells. The device performs two types of cellular characterization (impedance spectroscopy and micropipette aspiration) on a single chip to enable cell electrical and mechanical characterization. To investigate the performance of the device design, electrical and mechanical properties of MC-3T3 osteoblast cells were measured. Based on electrical models, membrane capacitance of MC-3T3 cells was determined to be 3.39±1.23 pF and 2.99±0.82 pF at the aspiration pressure of 50 Pa and 100 Pa, respectively. Cytoplasm resistance values were 110.1±37.7 kΩ (50 Pa) and 145.2±44.3 kΩ (100 Pa). Aspiration length of cells was found to be 0.813±0.351 μm at 50 Pa and 1.771±0.623 μm at 100 Pa. Quantified Young’s modulus values were 377±189 Pa at 50 Pa and 344±156 Pa at 100 Pa. Experimental results demonstrate the device’s capability for characterizing both electrical and mechanical properties of single cells.
    01/2011;
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    ABSTRACT: Mechanical force and geometric deformation that are applied on the cell will be transduced into biomedical signals which has been known as mechanotransduction. In turn, we expect that a particular cell function could be realized by giving a specific physical stimulus to the cell. In this work, a novel cell membrane strain model for circular cell membrane under indentation is developed. Based on this model, the deformation of the cell membrane is comprehensively measured. A cell strain modeling and control system is proposed to identify the deformability of the cell membrane and control the membrane to deform into the desired profile. The system employs the visual servoing to realize the feedback control on the cell membrane. An automatic cell boundary detection scheme is utilized to effectively optimize the visual module. With the developed control scheme, cells can be stressed into prescribed deformation without the knowledge of cells mechanical properties which enables the biologist to focus on the physical change of the cell and stimulate a desired activity in the cell by implementing the proposed system.
    Biomedical Robotics and Biomechatronics (BioRob), 2010 3rd IEEE RAS and EMBS International Conference on; 10/2010
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    ABSTRACT: Biological cells possess biochemical modules and physical shapes to maintain appropriate biological function. Different types of force and deformation are applied on cells to investigate the response and mechanical properties. In the biophysics field, studies use indentation deformation on cell membranes to examine the elastic-viscoelastic properties of biological cells. Experiments in different predefined profiles and frequencies are required to test the fidelity and predictive capability of cells creep function. The accuracy and the repeatability of the given stimulus are the significant factor in the experiments to obtain reliable measurements, which are very difficult to realize using manual operations. Automatic micromanipulation systems have substantial advantages over the conventional manual operations in aspects of reliability, accuracy and repeatability. In this paper, an automatic micromanipulation system is introduced and a series of experiments are conducted to stress zebrafish embryo in different sinusoidal profiles. The experimental results show that the system is able to stress the biological cell in desired stimulation and give consistent force outputs in realtime, meanwhile mechanical properties of the zebrafish embryo are also analyzed.
    01/2010;

Publication Stats

56 Citations
19.03 Total Impact Points

Institutions

  • 2011–2013
    • University of Toronto
      • • Department of Mechanical and Industrial Engineering
      • • Institute of Biomaterials and Biomedical Engineering
      Toronto, Ontario, Canada
  • 2010–2011
    • Nanyang Technological University
      • Division of Mechatronics and Design
      Singapore, Singapore