In this paper, we have constructed actively perfusable multiple hepatic lobule-like vascular networks in a 3D cellular structure by using magnetic tweezers. Without well-organized channel networks, cells in a large 3D tissue cannot receive nutrients and oxygen from the channel, and therefore, the cells will be dead after few days. To construct well-organized channel networks, we fabricated a hepatic lobule like vascular networks by using magnetic fields in our previous works. However, the size of the hepatic lobule like vascular network was more than five times larger than real hepatic tissue. To improve the previous research, we have proposed several things. First, we have constructed the vascular network having similar size of the real thing in this step. Second, we have cultured the constructed structure for a long-time (more than two weeks) to verify the biocompatible condition. Third, we assemble the constructed hepatic tissues to make a large size of organ, liver. Finally, an actively perfusable system have been adopted to implement a bioreactor system by adding micro pump.

We propose a novel adsorption pad for wall climbing robot and irregular surface object using capillary force and water sealing. We call this adsorption pad as Super Wet Adsorption pad. The SWA pad has a porous part and a capillary part. The porous part is made by salt reaching method. When the SWA pad adsorbs to the wall which some sand and dust are attached, water comes from the porous part to avoid vacuum breaking. The capillary part is connected to the porous part to supply and stock the water. In this paper, we show the design of the porous part and the capillary part, fabrication process of each parts, and perform the evaluation experiment of the capillary force and adsorption of uneven surfaces, demonstration of wall climbing robot and adsorption of irregular surface foods.

In this paper, we have fabricated a multilayered hepatic lobule-like vascular network in a 3D tissue using a heptapole magnetic tweezer. The tissue consists of cell-laden hydrogels with 3D channel networks. To fabricate multilayered channel system, magnetic hydrogel fibers were manipulated by a magnetic tweezer. The hepatic lobule tissue shows a hexagonal structure with different sizes of veins. Six portal veins transfer the blood including nutrients and oxygen to a central vein by sinusoids. The portal and central veins are made by steel rods, whereas the magnetic hydrogel fibers has a role of sinusoids. An important point of this research is to connect two veins - portal and central vein - by magnetic fibers. For this, we used magnetic tweezer with seven poles to magnetize the steel rods. In order to generate high magnetic fields, we design magnetic tweezer with a flat tip and additional lower tweezer based on simulation data. The manipulation was performed in fibrin gel inside rat liver cells. By applying high magnetic fields, we attracted magnetic fibers to the steel rods and constructed 3D channel network in cellular structure. To verify the efficiency of the channel, we supply culture medium to the channel and then analyze the cell viability according to the distance from the channel. As a result, the cells located at close to the channel show higher cell viability than others.

Fabrication of vascular network is an important research for transporting required nutrients and oxygen to the artificial tissues. In this paper, we propose a novel method to construct a hepatic lobule-like vascular network in a 3D cellular structure. The network is simply constructed by three types of veins, central vein, portal vein, and sinusoids. To realize these kinds veins, we utilize two different sizes of steel rods and magnetic fibers for delivering nutrients in 3D cellular structure. Alginate gel fibers embedding ferrite particles are prepared as the same length and are magnetized by magnetizer at 3T. A magnetic tweezer with seven poles is proposed to generate sufficient forces that can manipulate magnetized fibers. Here, two types of rods are magnetized to different magnetic poles in order to attract opposite the end of fibers. This manipulation process is performed in fibrinogen and thrombin solution with liver cells (RLC-18). After solidification of the solution, we deposit solutions with cells and fibers repeatedly, and therefore, a multi-layered structure can be constructed. In addition, we investigate cell a viability in fibrin gel according to the depth of the gel. The result is that the deeper the depth of the gel is, the lower the cell viability is. The cell viability is conducted in several condition. As a result, at the low temperature (here at 22 °C), the viability of cell is increased.

This paper describes a octo-rotor unmanned aerial vehicle (UAV) with one degree of freedom (DoF) manipulator for bridge inspection. The UAV has an ability to contact bridge pier to conduct hammering test. To control contact force applied by the UAV to the bridge pier, one DoF is enough for the manipulator implemented on the UAV. A preliminary experiment shows that the force is proportional to the pitch angle of the UAV when it contacts the bridge pier. A bridge pier contact experiment shows that our developed UAV can control contact force between its end-effector and the bridge pier; mean error of the contact force is 4.27 ± 3.64 [N] against 20[N] desired force.

In this research, we fabricated movable toroidal cell structures inside a microfluidic device for tissue engineering applications. A photo-crosslinkable biodegradable hydrogel gelatin methacrylate (GelMA) was employed to encapsulate biological cells for assembling cell structures. The UV light power and the concentration GelMA hydrogel were optimized to achieve both fabrication of microstructures and live condition of cells. The two-layered toroidal cell structures were fabricated which can mimic the multi-layered structure of blood vessels. The movable microstructures were achieved by the water repellent coating on the substrate surface. Finally, on-chip fabrication of GelMA microstructures and peeling off of the fabricated microstructures were achieved using a microfluidic chip. The results indicate that the fabricated movable GelMA microstructures can be used for further three dimensional assembly to achieve vascular-like tube structures.

In this paper, we propose a new method to assemble microstructures with biological cells towards in vitro 3D cellular structures. The proposed assembly method uses self-assembly process of magnetized toroidal microstructures. Biocompatible toroidal hydrogel microstructures are prepared by electrodeposition method, and ferrite particles are put on the fabricated structures using poly-L-lysine (PLL). The microstructures are magnetized by the magnetic field at 3 T, and assembled by the magnetic self-assembly process. Biological cells were encapsulated in the microstructures and cultured to achieve high density of cells inside structures. The magnetized microstructures were assembled automatically. The magnetic force generated from the ferrite embedded microstructures was estimated and compared to the fluid resistance applied to the microstructures. The proposed method can be applied to achieve 3D in vitro cell structures with vascular networks for tissue engineering applications.

In this paper, we conducted a new method to assemble microstructures inside a droplet named “Lab in a Droplet (LiD)”. The method can realize the assembly of micro-nano structures inside a droplet size. The surface tension is used to assemble microstructures automatically. Micro-scale or nano-scale objects are ejected from an inkjet nozzle. They are gathered at the center of the droplet and assembled by the surface tension. We conducted preliminary experiments to check whether the self-assembly of microstructures can be achieved by LiD. The experimental results show that the self-assembly of microbeads is conducted inside a droplet. The nano-scale objects can be patterned on a substrate depend on their sizes. A microstructure made of photo-crosslinkable resin was prepared, and microbeads were assembled with the microstructure inside a droplet. The method can be used for autonomous assembly of micro-nano structures in high precision.

This paper presents a fabrication method of multi-graphene box structure by a nanomanipulation in a Field Emission Scanning Electron Microscope (FESEM). To bend the multi-graphene in plastic deformation region, the bending stress were measured using a silicon cantilever based on the nanomanipulation. In this study, defects were introduced inside the multi-graphene on the folding line of the multi-graphene by irradiating an electron beam assisted with oxygen gas. From experimental bending stress measurement, the bending stress was dropped with electron beam irradiation in oxygen gas environment. The fabrication of 3D box structure of multi-graphene was demonstrated from a cubic net of multi-graphene which was fabricated by a Focused Ion Beam (FIB) etching process. For bending the one side of the cubic net graphene, a tungsten probe was used after reforming by FIB etching as end-effector of nanomanipulator. The multi graphene was bent to form a box structure in 3D space.

We have developed a highly functional untethered micro-robot that can manipulate cells with high gripping force in a micro-fluidic chip. The robot has gripping mechanism for grasping and transportation of cells with sufficient power. A permanent magnet is attached at the center of the gripping mechanism, and an electrical magnet controls the position of the magnet from the bottom of the micro-fluidic chip. The distance accuracy of the gripper is 3.0 μm, and it can activate about 50 Hz. The robot has four permanent magnets for positioning, and other four permanent magnets control the robot from the bottom of the micro-fluidic chip. The robot is made very thin and small to allow maneuverability in a micro-fluidic chip. We succeeded in high-power handling and cutting of a cell using this micro-robot.

In this study, we present a smooth enucleation process on a microfluidic chip. To improve the success rate of enucleation and increasing the potential viability of the enucleated oocyte, a microfluidic system is specially designed. Magnetically driven MicroTool (MMT) control the flow distribution in the microchamber. Designed microchannel with height difference is for the purpose of confining oocyte with its nucleus located in the withdrawal microchannel to achieve the high precision control in cutting volume. By utilizing these aspects, first, oocytes are sequentially loaded to the operation port; MMT constrains the oocyte location and controls the distribution of micro flow simultaneously letting hydraulic force cut off the nucleus from the oocyte. Enucleated oocyte is smooth in shape and incision is neat. With cutting volume control, this system can achieve high-speed enucleation with less cutting volume while removing the nucleus. Since the flow distribution could be managed by MMT significantly, therefore, the new system is proposed here to show advantages by the means of operation speed, cutting precision and great potentiality on continuous cutting process.

In the field of bioscience, such as regeneration medicine and cloning, the manipulation and analysis for cells are performed by many researchers. However, manual operation for such micro objects is not feasible and practical for beginner operators. As for the problem, we have developed a two-fingered microhand supporting manual operation. Using the microhand, we can manipulate cells i.e., grab, rotate, carry, and so on - like when using chop sticks. The stiffness measurement of a cell is a key approach in single cell analysis techniques. It is important in indicating cell condition, because the stiffness of a cancer cell is lower than that of a normal cell as an example. However, measuring stiffness is very difficult, because deformations of cell are plasticly, and many researches to measure the stiffness of cell don't deal with plastic deformation. So, in this paper, the cell hardness is calculated instead of cell stiffness by measuring the reaction force caused in the process of cell deformation via a micro force sensor attached to the end-effector of the microhand. Our results point out that this can be one efficient measurement method for acquiring cell hardness. In this paper, three topics are discussed. First one is the fabrication of the end-effector with micro force sensor. Second one is the method of measuring hardness of cell. As a last one, the hardness of the fibroblastic cell is measured by proposed method and the effectiveness of the proposal technique is shown.

We have developed a novel technique for fluorescent monitoring of a bovine oocyte nucleus for an automatic cloning device. Animal cells that have been chemically softened by cytochalasin and stained with Hoechst dye are aspirated into a thin microchannel of a microfluidic chip and stretched thin, allowing the nucleus of the expanded oocyte to be monitored. Half the volume of the oocyte is aspirated into the thin microchannel and a high-velocity fluid flow is generated in the wide microchannel to bisect the oocyte. Then, the half-oocytes are monitored to determine which contains the nucleus. To control flow velocity with high accuracy and rapid response, we also developed a syringe pump that is small, has no backlash, and has highly-accurate volume control and a good response for automatic cutting. In this report, we describe the monitoring method and construction of the syringe pump.

We have developed a novel technique for injecting and cutting animal cells for an automatic cloning system. Animal cells that have been chemically softened are aspirated into a narrow teflon tube, which is then inserted into a microfluidic chip. The tube's tip is inserted into a microchannel and releases the aspirated cells in the microchannel. The microfluidic chip contains two orthogonal channels. One is a narrow microchannel that aspirates and fixes a cell; in the other channel, a fluid flows at high velocity for cutting the aspirated cell. The thickness of the aspiration channel can be adjusted to fix the aspirated cell. Half the volume of the cell is aspirated into the narrow microchannel and high-speed flow is then generated to cut the cell into two. In this report, the cutting method and the injection method are described. Then an imaging process is also investigated for an automatic cutting.

Handling of microorganisms is of great interest in biology and biotechnology. Single cell capture technology has been demonstrated in our previous work with thermal gelation material and micro fluidic devise. This paper extends the system by local flow rate control to stabilize the trap with in-situ fabrication by photo-crosslinkable resin. Target cells are captured by gel and enclosed with the micro-structure. The cells, therefore, are protected from high-speed-channel flow or disturbances. This system succeeds in the separation and continuous culture of yeast cells, reaction and monitoring of the cultured cells stably by fluorescence staining in situ on a chip.

Isolation and separation of the target microbe is quite important. We propose a new touch sensor to get contact information that is needed for separation of the target microbe by the pipette. This sensor is sensitive enough to protect the fragile pipette tip from abrupt collision. Using this sensor, we developed a novel screening system for separation of target microorganisms from the randomly distributed samples on the plate by the local viscosity control of the thermosensitive hydro gel.

Reports separation of the target microbe by the laser trapped micro tools for minimum invasion of laser irradiation. The size of a micro tool (MT) is around micrometer. The micro tools are manipulated by the focused lasers under the microscope to manipulate the target microbe. We propose a pinpoint injection method of micro tools at the desired location in the micro chamber, which is filled with liquid. First, we classified the injection method of the micro tools in 4 categories. We employed a new method to install the micro tools inside the micro chamber. We developed a micro tool holding chip to install the micro tools. The micro tools were injected in the micro chamber, and were manipulated successfully by the laser scanning micromanipulator to separate the target microbe. The proposed method is useful for the pinpoint injection of MTs and separation by the indirect micromanipulation.

We developed a new system for random separation of a single microorganism, such as a living cell and a microbe, in a micro fluidic device under the microscope using laser manipulation and microchannel flow. The main flow in the microchannel splits at the exit of the sample chamber. One flow goes to the extraction port with high speed to take out the target. Another flow goes to the drain. The target was transported by laser manipulation from the sample chamber to put on the main flow. Since the force balance of the laser-trapped object is important for stable manipulation of the target, we propose the stagnation point control around the sample chamber exit. Pressure balance was adjusted and the stagnation point was controlled. Some preliminary experiments are conducted to show the effectiveness. The target was trapped by the laser transported to put on the main flow around the split area through the stagnation, and was taken out from the extraction port. Separation time was reduced less than 10 seconds.