This paper discusses biomimetic water strider robots that have microfabricated hydrophobic legs. Various kinds of supporting legs with hydrophobic microstructures on their surfaces were developed using MEMS (micro electromechanical systems) techniques. The lift and pull-off forces of these supporting legs were analyzed theoretically and then measured. The experimental results were in good agreement with the calculations. Two different mechanisms for autonomous water strider robots were developed. One robot with twelve microfabricated legs driven by a vibration motor successfully moved on a water surface and also made left/right turns by exploiting differences in the resonant frequencies of the legs. The other robot, with six microstructured legs, moved on water through elliptical motion of its middle legs, which is similar to the motion of actual water striders.

This paper describes the development of a multi-DOF (degrees of freedom) flexible robot based on the tongue. The authors focused on the tongue because of its "flexibility" and "soft motion". Motion of this robot is realized mechanically, and flexibility is achieved by covering the mechanism with a flexible structure. This robot consists of three parts: the tip, the body, and the base. In future, it would be applied in medical fields, e.g., for assistance in dysphemia, or in industrial fields, etc.

This paper describes the development and experimental results of a silkworm handling robot. Silkworm handling robot was developed for the purpose of automated breeding of silkworm larvae. The silkworm larvae are soft and amorphous. Therefore, gripping them is extremely difficult, and requires a specialized handling system. The authors succeeded in handling of a silkworm larva.

A method of micromanipulation using a microcoil array is proposed. Active coils drive permanent magnets on a work platform. The magnets can push mechanical parts to perform 2-dimensional assembly. Three-dimensional operation may be achieved from 2D magnet motion when the permanent magnets are part of a closed loop spatial linkage. Manipulation on a 4 cm/spl times/4 cm coil array was tested. Based on this large scale experiment, we fabricated a microcoil array using IC-based processes. A 4/spl times/4 microcoil array with 8 turns per coil was fabricated. The chip area including bonding pads, is 3.6 mm/spl times/3.6 mm. The minimum current necessary to attract a magnet and its speed were evaluated. A 0.6 mm/spl times/0.6 mm/spl times/0.3 mm magnet moved at 79 mm/s. The top speed for a magnet to follow a square trajectory was evaluated, and it was demonstrated that a 1.1 mg magnet could push a 13.4 mg object out of microcoil array.

The purpose of this research is to clarify moth emergent behavior by synthesis with currently developed tools, including living sensors and recurrent neural networks. The antennae on a silkworm moth are very sensitive compared with artificial gas sensors. These living antennae can be used as living gas sensors that can detect pheromone molecules with high sensitivity. Recurrent artificial neural networks are applied for controlling the pheromone tracing. As a result, a mobile robot with living antennae can follow a stream of pheromone like a male silkworm moth. The small numbers of neurons can generate moth-like behavior, including casting, and turning while interacting with the environment.

Two different principles for actuation of microactuators, the Lorentz force and the Coulomb force, are combined on the same device. Microactuators are fabricated using conventional semiconductor technologies. The actuator patterns are etched out from a 1 /spl mu/m Al thin-film on a Si wafer. A simple model of an electrostatic actuator, for parallel electrodes, is introduced. If this actuator performs work against a spring, the displacement versus voltage executes a hysteresis curve. In the present paper the combination of Lorentz force and Coulomb force produces actuation forces in all 3 spatial directions (x, y, and z), and as an application example an xyz-table was built.

Magnetic force is useful for manipulating objects without contact. We propose a method of micromanipulation using this force. The concept is based upon linkage-free end-effectors and different from the concept of serial-link manipulators. Multiple cylindrical permanent magnets work as end-effectors. The permanent magnets on the stage, above an arrangement of solenoids, manipulate objects by pushing. Furthermore, 3D manipulation can be achieved as a link mechanism is used. A prototype of the manipulator has been fabricated. The manipulation field measures 4.5 cm/spl times/4.5 cm and consists of 6/spl times/6 solenoids. The magnets are 6 mm in diameter. The ability of a magnet to follow a control signal and the force for pushing an object have been evaluated. Furthermore, a prototype of the link mechanism has been fabricated. The vertical force for pushing down and pulling up an object have also been evaluated.

The lift and drag coefficients, C/sub L/ and C/sub D/, were measured for miniature airplane shaped structures, approximately 2 mm in length, made from silicon. The airflow regime surrounding the structures was laminar, similar to that found around comparably sized flying insects. The structures were attached to the tips of finely drawn, 30 /spl mu/m diameter glass rods, which were then placed inside a laminar fluid flow, with Re ranging from 76 to 207. By measuring the forces on the airplane due to lift and drag, C/sub L/ and C/sub D/ can be determined. The drag coefficient was found to be relatively independent of attack angle, increasing by only about 50% between 0/spl deg/ and 90/spl deg/. The experimental results, C/sub L/=0.5-1, and C/sub D/=1-4, were compared to values found using FEM analysis.

Microcoils are less efficient due to the scale effect, but if a permanent magnet is used, the result is a quite scale-independent magnetic field strength. 2D-microstructures of various shapes have been etched out from a 1 /spl mu/m aluminium thin-film. These structures are locally released from the wafer by undercut etching. By sending an electric current through them, a Lorentz force component is induced in some sections, resulting in deformation of the thin-film structure. First, different shapes of 1-turn coils are presented. The arrangement of vertical and parallel magnetic field is discussed. Micromachine fabrication using IC thin-film, lithography and etching technology is presented. An x-y table was built as an application example for the use of Lorentz force in micromachines. For protection and the ease of handling the microactuators are packaged into a standard IC case. As examples of further applications of Lorentz force actuators, a micromirror device, a ciliary motion system and microrelays are discussed.

A male silk moth (Bombyx mori) pursues a female by following a pheromone, called Bombycol. This action is caused by only a few molecules of pheromone which arrive at the antenna of a male silk moth. The antenna has very sharp sensitivity and specificity. In this paper, the use of a biological sensor is discussed as a new type of sensor, in other words "living sensors". The electrical activity of a silk moth antenna, called the electroantennogram (EAG) was obtained using self-made electrodes and amplifier. Two pheromone sensors were attached to a simple mobile robot to determine the direction of a pheromone trace. From this information, we were able to control the direction of the robot. The robot followed the pheromone trace just like a real male silk moth.

An electrostatic actuator which can be applied to the joints of movable parts in a micro system was developed. An elastic plate (length: 105-520 /spl mu/m width: 13 /spl mu/m, thickness: 0.5-1.3 /spl mu/m) is bent by electrostatic force when a voltage of 40-100 V is applied The required voltage depends mainly on the initial curvature of the elastic plate. This curvature can be controlled by changing the thickness ratio of the Al and Ni layers, which are sandwiched together to comprise the elastic plate. It was found that the radius of curvature is mainly proportional to the thickness ratio (Ni thickness/Al thickness) in the range of 0.1 to 0.4, and that the gradient of its proportion is larger when the Al film is thicker. Control of the elastic film curvature also enables the fabrication of three dimensional mechanisms without handling or assembly.

The conventional method for calculating aerodynamic forces generated on objects is based on the aerodynamics in the high Reynolds number flow, like the airflow around the wings of airplanes, because little is known about the low Reynolds number flow. Using this method to calculate the aerodynamic force acting on a flying microrobot, the obtained results may differ from the actual values. For analysis of this difference. The large-scale models of wings for flying microrobots were made, whose wing lengths are 3 cm and 1.5 cm respectively. With these wings the experiments were done in the low Reynolds number flows (Re=385, 752). The drag forces measured in these experiments were compared with the ones from calculations. As a result, in both flows, the measured values were larger than the calculated one. Using semiconductor surface machining technology, we also fabricated a flapping mechanism with the wings that generate the difference of the drag forces during upstroke and downstroke movements.>

In this article, we propose a new analyzing method for self-assembling systems. Its initial purpose was to predict the yield—the final amount of desired product—of our original self-assembling mechanical model. Moreover, the method clarifies the dynamical evolution of the system. In this method, the quantity of each intermediate product is adopted as state variables, and the dynamics that dominates the state variables is derived. The behavior of the system is reduced to a set of difference equations with a small degree of freedom. The concept is the same as in chemical kinetics or in population dynamics. However, it was never applied to self-assembling systems. The mathematical model is highly abstracted so that it is applicable to other self-assembling systems with only small modifications.

The authors describe the concept of making a microrobot with an external skeleton like the structure of an insect, as well as its implementation using rigid plates and elastic joints. A large-scale model consisting of plastic plates, springs, and solenoids is shown to demonstrate this motion. Moreover, several microsized models were built on silicon wafers by using polysilicon as rigid plates and polyimide as elastic joints.>

The authors investigate animal gaits and compare them with robot gaits in order to determine the parameters of the dynamic walk of robots. Several parameters are introduced to analyze gaits. These parameters can be normalized, using the equation of motion of an inverted pendulum. The experimental relations among the parameters give a gait which is efficient.>