We propose a microrobotic platform that stimulates swimming microorganisms in a microfluidic chip with high speed and accuracy. The developed platform comprises (1) high-speed microrobots that can generate a millinewton-level driving force, micrometer-level positioning accuracy, and a millimeter per second level drive speed through the actuation of motorized stages with permanent magnets and (2) high-speed online vision sensor capable of capturing images on the order of 1000 frames per second. The specific design and architecture of the proposed platform are also presented. The proposed platform stimulates and observes swimming microorganisms in a microfluidic chip through a mechanical approach. This platform provides on-chip investigation with high functionality that has been difficult to achieve with previous approaches and contributes towards the discovery of previously unknown functions of swimming microorganisms in the bioscience fields.

Ankle-foot orthoses (AFOs) are orthotic devices that support the movement of the ankles of disabled people, for example, those suffering from hemiplegia or peroneal nerve palsy. We have developed an intelligently controllable AFO (i-AFO) in which the ankle torque is controlled by a compact magnetorheological fluid brake. Gait-control tests with the i-AFO were performed for a patient with flaccid paralysis of the ankles, who has difficulty in voluntary movement of the peripheral part of the inferior limb, and physical limitations on his ankles. By using the i-AFO, his gait control was improved by prevention of drop foot in the swing phase and by forward promotion in the stance phase.

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.