Kazuhiro Yoshida

Tokyo Institute of Technology | TITech ·  Precision and Intelligence Laboratory

Organ-on-a-chip is a microdevice to reproduce the functions of organs and has recently attracted attention for their use in preclinical studies for the new drug development. Thanks to the physical stimulation applied to cells by repeatedly stretching a porous membrane across which two layers of living tissues were cultured, the cell-cell communicat...

In the past decades, the robotics community has made great progress in the development of soft robots that are inherently safe in their interaction with their environment. However, the compliance of these robots also comes with drawbacks, such as the fact that soft structures cannot easily exert high forces on their environment. In this work, we pr...

For power microrobots that perform power-needed tasks in narrow spaces, we have proposed an alternating pressure system using ER valves. The ER valve controls an ERF (electro-rheological fluid) flow with its increased viscosity due to an applied electric field. In the alternating pressure system, an alternating flow is rectified with synchronously...

For power microrobots that work in narrow space such as inside of pipes of industrial plants, microactuators using ER microvalves that control ERF (electro-rheological fluid) flow due to the apparent viscosity change in electric fields (ER effect) have been investigated. Higher pressure can realize higher performance due to the decreased cross sect...

For maintenance of pipes in industrial plants and so on, in-pipe microrobots that perform power-needed tasks have been required. We have called this kind of robots the power microrobots and developed them using high density hydraulic power. We have proposed and developed a micropump using fluid inertia as a micro hydraulic power source. The micropu...

UV-LIGA process has manifested its potential in the fabrication of high-aspect-ratio metallic microstructures. However, how to attain the complete, fast, and non-swelling removability of the crosslinked SU-8 micromolds remains a grand challenge. To address this challenge, we propose an effective and efficient removing method utilizing CO2 laser abl...

Because of the power density advantages of fluid power systems, many researchers have developed microactuators using homogeneous electrorheological (ER) fluids (ERFs) for applications to various micromachines. An ER valve, as a critical component of the ER actuator, can control ERF flow by the apparent viscosity increase resulting from the applied...

The traditional power sources for generating droplets are bulky devices such as syringe pumps, constant pressure systems and so on, resulting in difficult integration with other microfluidic components. To overcome this limitation, we propose and develop a droplet generator with its power sources on a chip (22 × 21 × ~ 1 mm). The compact droplet ge...

The previously reported O/O (Oil-in-oil) droplet generators are based on the usage of microfluidics and membrane emulsification techniques powered by external bulky syringe pumps. This configuration brings problems such as dead volume, air contamination, and difficult integration with other microfluidic components. The paper proposes an O/O droplet...

The previously reported unidirectional ECF micropumps are not applicable to some soft actuators, which need inflating and deflating processes. To overcome this limitation, we propose, design, fabricate and characterize an ECF (Electro-Conjugate Fluid) bidirectional micropump. The simply designed bidirectional ECF micropump has five sets of electrod...

The wet etching and physical stripping methods are typical methods to release independent SU-8 structures. However, it is difficult to release SU-8 structures by chemically etching sacrificial layers under the large footprint area especially, while the physical stripping method leads to a large deformation due to soft substrates. To overcome these...

This paper proposes a novel SU-8 adhesive tape by using the dose-controlled UV exposure method, which enables the fast packaging with fluidic interconnections for microfluidic sensors and actuators. The conventional packaging for microfluidic devices demands two complicated steps: (1) to drill the fluidic connections on the glass cover in the first...

The vertically allocated free-standing SU-8 microstructures are typically bonded to a glass cover by the usage of uncrosslinked SU-8 adhesives. Such a phenomenon can easily cause SU-8 protrusion and eventually result in the SU-8 cantilever to be immovable. Traditional methods are sensitive to the bonding conditions and have a short bondable thickne...

This paper proposes and develops a novel fabrication method to realize a micro vertically-allocated SU-8 check valve. The ordinary vertically-allocated SU-8 check valve formed by the photolithography has a limited overlap between an SU-8 cantilever and its valve seat, resulting in the low diodicity (i.e. the ratio of the forward flow to reverse flo...

A common method to release crosslinked SU-8 structures from the substrate is to chemically dissolve a sacrificial layer under the SU-8 structure. It is necessary for the sacrificial layer to tolerate SU-8 solvent or developer during the spin-coating, soft baking, or developing of SU-8 and to selectively be dissolved without any damage on SU-8 struc...

Previously, we have developed ECF micropumps with triangular prism and slit electrode pairs (TPSEs) fabricated by the UV-LIGA. However, the previous KMPR molds have a limit to attain higher-aspect-ratio TPSEs. As a promising substitute, the ultrathick SU-8 molds are preferable for the TPSEs due to higher-aspect-ratio ability, but their difficult re...

This paper describes the fabrication of a vertically-allocated SU-8 cantilever in a closed fluidic channel. The difficulties to fabricate the vertically-allocated SU-8 cantilever inside the closed channel mainly lie in which kinds of sacrificial layers under the cantilever and sealing methods for enclosing the channel are utilized for the movabilit...

The 20th century's robotic systems have been made from stiff materials, and much of the developments have pursued ever more accurate and dynamic robots, which thrive in industrial automation, and will probably continue to do so for decades to come. However, the 21st century's robotic legacy may very well become that of soft robots. This emerging do...

The 20th century’s robotic systems have been made out of stiff materials and much of the developments in the field have pursued ever more accurate and dynamic robots which thrive in industrial automation settings and will probably continue to do so for many decades to come. However, the 21st century’s robotic legacy may very well become that of sof...

This study is to investigate the impact of geometrical parameters on the micro check valves by using FEM (finite element model) and experiments. The micro check valve has two parts: An SU-8 cantilever and the others. Seven groups of cantilevers with different geometrical features, such as the length, the width of the cantilever and top gap, have be...

Developing miniature robots that can carry out versatile clinical procedures inside the body under the remote instructions of medical professionals has been a long time challenge. In his paper, we present origami-based robots that can be ingested into the stomach, locomote to a desired location, patch a wound, remove a foreign body, deliver drugs,...

For maintenance microrobots for small diameter pipes in power plants and so on, a novel microgripper using divided-electrode type flexible electro-rheological valves (DE-FERVs) was proposed and developed. Each bendable finger consisted of the DE-FERV and a hydraulic rubber actuator and was several millimeters long. The DE-FERV had an axially divide...

This paper presents a novel MEMS-based electro-rheological (ER) microfinger system with an alternating pressure source for multiple microactuator systems. Based on rectifying alternating flow by the ER microvalves, the ER microfinger system enables half number and small size of supply and return pipes, which is suitable for multiple microactuator s...

This paper proposes and develops a multiple ER microactuator system using an alternating pressure source for in-pipe working micromachines, medical microrobots, and so on. A hydraulic microactuator is known to have high power density but also has the drawback of requiring large piping space for the supply and return of the working fluid. In this st...

For a micromachine having multiple high-power microactuators such as an inpipe working micromachine, a multiple-microactuator system using a high-frequency pressure source was proposed and developed. The system consists of a high-frequency piezoelectric pressure source, hydraulic microactuator units, and pipes; the hydraulic microactuator unit cons...

The paper presents a 3-DOF microactuator having a Fluid Inertia (FI) micropump and ER microvalves for in-pipe working micromachines of about 10 mm in diameter, and so on. The ER microvalve controls an Electro-Rheological Fluid (ERF) flow due to the apparent viscosity increase in the electric field. The FI micropump generates high-output-fluid power...

This paper presents a novel magneto-theological (MR) valve-integrated cylinder and its use in manipulator operations. Conventional MR valves are flow channels that have magnetic poles and control MR fluid flow by using the apparent viscosity change created by the application of a magnetic field. The proposed MR cylinder consists of an electromagnet...

An electro-conjugate fluid (ECF) generates jet flow in inhomogeneous electric field. Electro-rheological fluid (ERF) and magneto-rheological fluid (MRF) change their apparent viscosities in electric or magnetic field. Such functional fluids are expected to realize new promising actuators with simple and miniaturizable structure without sliding part...

The paper proposed and developed a flexible ER microactuator called FERMA for in pipe working micromachines, medical micro robots, and so on. An ER microvalve has a narrow flow channel with electrodes and controls flow of homogeneous electro-rheological (ER) fluid using the apparent viscosity change in an electric field. A conventional ER microactu...

Fluids with a controllable viscosity gained a lot of interest throughout the last years. One of the advantages of these fluids is that they allow to fabricate hydraulic components such as valves with a very simple structure. Although the properties of these fluids are very interesting for microsystems, their applicability is limited at microscale s...

Fluids with controllable flow properties have gained considerable interest in the past few years. Some of these fluids such as magnetorheologic fluids are now widely applied to active dampers and valves. Although these fluids show promising properties for microsystems, their applicability is limited to the microscale since particles suspended in th...

For millimeter-sized working micromachines using fluid power with high density, a novel microvalve with simple structure using magneto-rheological (MR) fluid is proposed and called the micro MR valve. The micro MR valve utilizes the apparent viscosity controllability of the MR fluid in the magnetic field. To control sufficiently high magnetic flux...

For millimeter-sized fluid-driven micromachines performing power-needed tasks, we proposed a novel micropump using fluid inertia in an outlet pipe. The paper describes the pump structure for higher output power and an application of the micropump to a micro fluid power system. First, a simple nonlinear mathematical model with lumped parameters was...

The paper proposed and developed a piezoelectric micropump using a resonantly-driven active check valve for millimeter-sized powerful micromachines using homogeneous ER fluids. Feasibility of the valve was experimentally confirmed using a pump large model. Then, a micropump was fabricated with Φ9.5mm×9.8mm in size and a part of the characteristics...

As an advanced control component for practical micromachines using fluid power in millimeter size, the authors have proposed and developed a microvalve using homogeneous electro-rheological (ER) fluids called micro ER valve and verified the validity through basic experiments using several micro ER valves fabricated by conventional machining. In thi...

To realize autonomous manipulators which work outdoors, 3-D vision sensors are required to measure objects and environments under severe conditions. The authors have proposed a real-time motion stereo vision which measures 3-D coordinates of objects with simple calculations based on brightness gradient of images captured by a motion camera. In this...

As an advanced control component for practical micromachines using fluid power in millimeter size, the authors have proposed a micro ER valve using homogeneous ER fluids and verified the validity through basic experiments using several micro ER valves fabricated by conventional machining. In this paper, to control micro grippers mounted on micromac...

For micromachines using fluid power with high power density, a novel microvalve using Magneto-Rheological Fluids (MRF) drop is proposed. The MRF drop is supported as a valve by a permanent magnet and is moved by electromagnets to control the opening. The proposed microvalve solves leakage problem caused by the large machining errors compared with i...

To realize autonomous manipulators which work outdoors, 3D vision sensors are required to measure objects and environments under severe conditions. The authors have proposed a real-time motion stereo vision which measures 3D coordinates of objects with simple calculations based on brightness gradient of images captured by a motion camera. In this p...

To realize practical high power micromachines, the authors have proposed a simple microvalve using homogeneous ER fluids and are developing a micropump-mounted in-pipe mobile micromachine with 9mm in diameter. In this paper, firstly, 2-port micro ER valves are fabricated by micro machining and some kinds of homogeneous ER fluids' characteristics ar...

To realize micro maintenance robots for small diameter pipes of nuclear reactors and so on, high power in-pipe mobile micromachines have been required. The authors have proposed the bellows microactuator using fluid power and have tried to apply the actuators to in-pipe mobile micromachines. In the previous papers, some inchworm mobile machine prot...

To realize practical micromachines using fluid power with high power density, a micro fluid control system using homogeneous ER (electrorheological) fluids is proposed and fabricated. Homogeneous ER fluids such as nematic liquid crystals change their viscosity with applied electric field strength and is usable in micro flow channels without dispers...

To realize practical micromachines using fluid power with high power density, a micro fluid control system using homogeneous ER fluid is proposed and developed. Firstly, a new micro ER (electrorheological) valve using homogeneous ER fluid is proposed and fabricated. Its diameter is 9 mm. Static and dynamic characteristics are investigated. With sup...

To realize autonomous manipulators which work outdoors, 3D vision sensors having capability of real-time processing, robustness against sunlight, and compactness are required to measure objects and environments. In this paper a simple real-time motion stereo vision is proposed, which utilizes direct calculation of the integrated gradient constraint...

A novel control valve using MR fluid (MR valve) is proposed for fluid control systems. The MR or Magneto-Rheological fluid is a newly developed functional fluid whose apparent viscosity is controlled by the applied magnetic field intensity wider than that of Electro-Rheological fluid. The MR valve consists of a flow channel between a pair of magnet...

As a power source for practical micromachines such as in-pipe mobile micromachines using fluid power, micropumps having high power density are required. In this paper, a piezoelectric micropump using resonance drive is proposed and developed. It basically consists of a bellows as a flexible pump chamber with an additional mass, a piezoelectric actu...

In this study, a piezoelectric micropump using resonance drive is proposed and fabricated. Fabricated piezoelectric micropump basically consists of a bellows acting as a reciprocating pump chamber, a multilayered PZT actuator for oscillating the bellows and normally closed cantilever type of two check valves. Frequency characteristics of flow rate...

A new-type liquid driving electrostatic micromotor is proposed. One of the authors found that dielectric fluids such as dibutyl decanedionate which have some kind of chemical structure form jet flows in applied electrostatic fields. The proposed motor utilizes a propulsion force due to the jet flows and a simple structure driven by a simple DC powe...

In-pipe mobile micromachines have many applications including micro-maintenance robots for nuclear reactors and are expected to be realized in the near future. To realize practical in-pipe mobile micromachines, microactuators with sufficiently high output power are necessary and we have proposed the bellows microactuator which utilizes fluid power....

Electro-rheological fluids (ER fluids) allow direct interfacing between electric signals and fluid power without moving parts such as servo valves having spools driven by solenoids. In this paper, we apply ER fluids to fluid power control systems, especially to mini flow control valves (mini ER valves). A four-ports mini-ER valve whose size is 22mm...

To realize a small size proportional valve with simple structure, a spool driving actuator using shape memory alloy (SMA) fine wires in arrayed arrangement is proposed and the response is investigated, Firstly, the basic characteristics of the actuator are stated. Secondly, a proportional valve is fabricated and tested with constant cooling oil flo...

To realize a small-size proportional valve, a small-size and sufficiently high-stiffness actuator is required to drive the spool. However, with conventional actuators, such as solenoid actuators, it was difficult to realize such performance. In this study, an actuator using shape-memory-alloy (SMA) fine wires in arrayed arrangement is proposed and...

For more efficient use of micro-machines, micro-actuators using fluid power were investigated. An in-pipe mobile machine is one of practical micro-mechanisms and a simple machine using the bellows actuators was constructed previously. The machine is able to move like an inchworm due to the three actuators, however, it has to pull three power supply...

For realizing practical actuators for micro-mechanisms, actuators using fluid power (called the “fluid actuators”, hereafter) are investigated. First, the miniaturization characteristics of three kinds of fluid actuators are analyzed and the results are compared with those of five typical actuators such as an electro-static actuator and so on. The...

The early detection of minute cancer is very important, but that is difficult when using X-ray, ultrasonic, or an endoscope because of the small size and the disturbance by mucus. However that is said to be easy with direct palpation if possible. Then the paper proposes a new hardness sensor for cancer palpation, which is inserted into a human body...

The adhesive mechanism to flexible surface is more and more important for a medical electrode, the future minute medical machine which moves and inspects in stomach, and so on. In order to investigate the superior adhesive mechanism, the authors take up the suction electrode for electrocardiograph which is now desired to improve and also can be the...

Real-time stereo vision using a multiple arrayed camera system, named MAC vision, is proposed. MAC vision processes the correspondence problem, one of the basic problems in stereo vision, very rapidly by making use of the simple geometric relationship of images on the same-height scanning lines. Several problems involved in MAC vision are discussed...

The fast Fourier transform is very often used when time or spatial signals must be decomposed into their components. Zoom-FFT can be used if the resolving power of frequency should be increased to precisely determine the time or spatial frequencies and the phase angles of the components. However, the zoom-FFT requires many periods of the signals fo...

A new position identification method for mobile robot is proposed. The method is to find out own position and orientation of the robot in wide unknown environment by means of horizontal cross section information measured by the range finder and compare it with pre-registered map information. The map information is expressed by five geometrical char...

The 3D vision is indispensable for realization of an intelligent robot. The stereo vision has been considered as a typical candidate for 3D visions, but it is not yet practically used. The bottleneck in realizing the stereo vision was a corresponding problem which is to correctly identify the same viewing point for each camera. The paper proposes a...

The basic problem in generating terrain maps for a mobile robot using three-dimensional information from a range-finder is considered. The representation of terrain maps is first investigated and a method called torus memory representation is introduced. The method of generating terrain maps is divided into visible and invisible regions, which are...

The authors have developed a laser range finder (LRF) which enables a mobile robot to measure the distance to a natural object located 1-5 m ahead with an error less than 2%. The system uses a laser as weak as 1 mW, a safe level for human eyes, and is workable under bright daytime sunlight of about 100000 lx. This LRF can quickly process data and m...

For better terrain adaptability, a walking robot should be equipped with a visual sensor. This paper defines the visual sensor for a walking robot as a map realization system, abbreviated MARS, and investigates the way to realize a practical 3-D range-finder which forms the major part of a MARS. First, the improvement in the range-finder's performa...