Two-dimensional Manipulation Research Articles

Two-Dimensional Manipulation and Orientation of Actin−Myosin Systems with Dielectrophoresis

Molecular motors, as autonomous transporting and sensing systems, may play an important role in nanoscale technologies such as analytical and electromechanical systems. It is important to establish control of the patterning of deposition and to control the molecular motor-induced transport. Application of electrical signals to control motor motility is necessary for their integration with silicon electronics. We have applied dielectrophoretic (DEP) forces with quadrupole electrodes to pattern actin on a substrate. In addition, DEP torque(s) directed the motion of actin on myosin substrates along electric field lines. These are our first steps toward building an on-chip, integrated, biomotor analytical system.

On the Technology of Acoustic Utility. Acoustic Information and Energy. Two-Dimensional Micromanipulation Using an Ultrasonic Standing Wave Field Generated by Crossing Sound Beams.

As a non-contact maicromanipulation technique, it is possible to trap particles in water at nodes of an ultrasonic standing wave field generated between a transducer and a reflector and to transport them using a frequency-shifting operation. Since there are several problems coming from resonance of the sound field with this scheme, the authors proposed a novel manipulation technique for particles using a standing wave field generated by two transducers whose sound beam axes were crossing to each other and accomplished one-dimensional manipulation of a polystyrene particle. The present paper describes an extension of this method adding one more transducer, which realizes two-dimensional manipulation suppressing unstable motion observed in the one-dimensional operation. Experiments in water using polystyrene particles confirmed the principle of the two-dimensional manipulation and agreed well with a numerical analysis of the sound field.

Two-dimensional manipulation of differentiated Madin-Darby canine kidney (MDCK) cell sheets: the noninvasive harvest from temperature-responsive culture dishes and transfer to other surfaces.

A renal epithelial cell line, Madin-Darby canine kidney (MDCK) cells, adheres, spreads, and proliferates to confluency on our developed temperature-responsive culture dishes grafted with a poly(N-isopropylacrylamide) (PIPAAm) at 37 degrees C. In addition to other cell types, including hepatocytes and endothelial cells, MDCK cell sheets noninvasively were harvested from PIPAAm-grafted dishes merely by reducing the temperature. However, during the early stage of culture (up to 3 weeks), confluent MDCK cell detachment is greatly repressed. In the present study, we succeeded in the rapid harvest of confluent MDCK cell sheets and intact transfer to other culture dishes by utilizing hydrophilically modified poly(vinylidene difluoride) (PVDF) membranes as supporting materials. Immunocytochemistry with anti-beta-catenin antibody revealed that the functional cell-cell junctions were well organized in the transferred MDCK cell sheets. The viability assay showed that the transferred cells were not damaged during the two-dimensional cell-sheet manipulation. By transmission electron microscopy it was confirmed that the harvested MDCK cells retained differentiated phenotypes and had many microvilli and tight junctions at the apical and lateral plasma membranes, respectively. This two-dimensional cell-sheet manipulation technique promises to be useful in tissue engineering as well as in the investigation of epithelial cell sheets.

Control of a Standing Wave Field Using a Line-Focused Transducer for Two-Dimensional Manipulation of Particles

Control of the positions of particles using acoustic radiation pressure in water was studied to develop a noncontact micromanipulation technique. In this paper a method to transport the particles two-dimensionally using an ultrasonic standing wave field between a line-focused transducer with multiple electrodes and a reflector placed at the focal line is described. When alumina suspension of mean diameter 16 µm was poured into the standing wave field of 2.1 MHz, the particles were trapped and agglomerated at sound pressure nodes existing at half wavelength on the sound beam axis near the reflector. Changing the frequency alters the wave-length and hence the interval of agglomeration. Therefore the trapped particles were transported along the sound beam axis. When the next electrodes were driven, the standing wave field shifted laterally and the trapped particles moved to the corresponding nodal points. Thus two-dimensional transportation was realized using the line-focused transducer. A sound field generated by the line-focused transducer was discussed based on numerical calculations to design an optimum shape of a transducer for manipulation.

Two-dimensional manipulation of confluently cultured vascular endothelial cells using temperature-responsive poly(N-isopropylacrylamide)-grafted surfaces

Temperature-responsive hydration/dehydration changes in surface-grafted poly(N-isopropylacrylamide) (PIPAAm) were utilized for hydrophilic/hydrophobic surface property alterations in cell culture. In this report, we utilized PIPAAm-grafted surfaces to recover confluently-cultured vascular endothelial cells as coherent monolayers from this cell culture substrate and to transfer to new cell culture substrates. For this purpose, we used two different methods to recover and transfer cell monolayer cultures: (1) chitin membranes used as an apical side cell support during cultured cell transfer, allowing cell basal side reattachment to new culture substrates after transfer; and (2) a cell culture insert™ (porous PET) used as both a support as well as new substrate, allowing basal surfaces of cultured cells to be exposed to the medium after transfer. In both cases, all cells grown on PIPAAm-grafted surfaces detach completely with maintenance of basement membrane-like structure. Recovered cells attach to the second culture surfaces, covering more than 60% of the new substrate, and retain approximately 90% viability and their original function as judged from tissue-type plasminogen activator secretion. This technique could be utilized to prepare novel bioartificial organs as well as cell co-culture systems by multi-layering different cell types to mimic tissue structures for tissue engineering.

Ultrasonic Micromanipulator Using Visual Feedback

We have proposed ultrasonic micromanipulation (UMM) techniques for micron-sized particles in liquid based on the radiation forces of very-high-frequency (VHF) ultrasound. In this paper, we report new UMM techniques using visual feedback techniques. To generate VHF ultrasound, a beam-width-compression leaky wave transducer with a frequency of 50 MHz is used. The 50-µm-diameter SiO2 glass sphere and the polystyrene sphere are used as test particles. As an example of two-dimensional manipulation, the transportation of particles along circle and character patterns are demonstrated. The selective trapping of a glass sphere is also shown.

Two-dimensional cell manipulation technology. An artificial neural circuit based on surface microphotoprocessing.

The precise regional control of cell adhesion and growth on a substrate may create two-dimensional tissue formation, as in a neural network. To prepare a neural circuit, micropositioning of neural cells and guidance of extending axons in a given region are required. In general, the adhesion of neural cells and their axonal extension are mediated by adhesive proteins found in the extracellular matrix. This paper describes a novel surface photoprocessing that enables the creation and guidance of regionally selective cell adhesion, leading to a neural network. The non-adherent region was created by chemical fixation of a photoreactive hydrophilic co-polymer of azidostyrene and N, N-dimethylacrylamide on a hydrophobic substrate. Ultraviolet irradiation with the use of a photomask placed on a substrate hydrophilically modified the irradiated regions, which was evident in ESCA and contact angle measurements. The addition of a collagen buffer solution resulted in collagen adsorption only on the non-irradiated hydrophobic portions. Seeded neuroblastoma cells adhered only on collagen-adsorbed pathways 130 microns in width. One day after seeding, nerve growth factor was added to the culture medium, resulting in cell differentiation from growth to axonal extension. The axons grew along the collagen-adsorbed pathways. Sooner or later, cells were interconnected with extended axons, which was clearly visible microscopically. Further culturing completed the honeycomb-like patterning, as designed. The surface processing developed here can manipulate fundamental cellular behavior, leading to two-dimensional patterned tissue, which may provide information on the morphogenesis of the neural network and neurotransmission.

Relational-linear quadtree approach for two-dimensional spatial representation and manipulation

An approach called relational-linear quadtree which provides information at multiple resolutions to describe spatial features together with descriptive or propositional information in desired structures is presented. It also provides powerful and flexible spatial analysis and manipulation ability. Its principle is quite clear, and implementation is very easy. It can be modified to fit other database models or structured knowledge representation schemes and can be implemented on most database management systems (DBMS) or expert system tools which support the structured models or schemes. The only extension is a set of quadtree operators which involve arithmetic operations on integers that can be coded as routines in a host language or a system command language. No additional processor is needed. This advantage makes the relational-linear quadtree a very practical approach in making use of the existing DBMSs or expert system tools to develop spatial information processing systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

位置および剛性制御に基づく多指ハンドの操り制御

A position/stiffness-based manipulation control for a multifingered robot hand is proposed. In the proposed method, an object is manipulated by controlling each fingertip trajectory according to the desired trajectory for a manipulated object. Furthermore, the stiffness/damping control is also introduced at each fingertip to achieve the stability and the desired dynamics of the manipulation. Compared with the conventional force-based manipulation, the proposed control method is rather simple in algorithm, and without changing control modes, also enables to make finger motion task plans in constraint and unconstraint environments, since it is based on the position control.The fundamental formulation of proposed control method is described precisely and the dynamics of manipulation is analytically investigated. These considerations are experimentally confirmed on two-dimensional manipulation using a two-fingered robot hand with the stiffness control capability.