A general purpose measurement system has been developed which can measure very low torques of the order of 10 −7 N m. The new method proposed here uses wind pressure to apply a load to a turbine attached to the output shaft of a device. It can therefore be used for all rotating microdevices. The use of wind pressure reduces the loss during measurements, and makes it possible to measure low levels of torque easily by simply attaching the turbine to the device. In the present study, the measurement principle of the new system has been verified. The static friction torque was measured by the traditional method of using a thread wound around the motor shaft in order to examine the validity of the proposed method, and a comparison of the two methods with the measured data is presented. In addition, a prototype micromotor, 1.6 mm in diameter, has been fabricated and used to demonstrate that the new system is able to measure torques of the order of 10 −7 N m while the motor is in operation.
A hydrodynamic gas bearing able to reduce power losses is selected, and the possibility of reducing its size is examined. The first consideration is how laser-assisted etching can be employed to form spiral grooves on the cylindrical shaft. In a hydrodynamic gas bearing, the shaft and bearing come into contact with each other when the actuator is started and stopped. It is thus necessary to reduce the frictional torque during starting and to ensure a satisfactory level of wear resistance. Next, the grooved shaft surface is modified by ion mixing. Its sliding characteristics are investigated to assess the reduction in friction and improvement in wear resistance. This reveals that it is possible to form a spiral grove 6 Y m in width and 2 , u m in depth on a 0.5"-diameter shaft. It is also established that, by forming a CrN film on the shaft, it is possible to achieve a friction coefficient of approx. 0.2, representing a satisfactory wear resistance. It is thus concluded that the hydrodynamic gas bearing selected can be used as a micro-actuator component.
Current methods of assembling micromachines, for example handling components using a manipulator, require accurate component positioning. In addition, it is difficult to establish electrical connections between the components with thlese methods. To solve these problems, this paper investigates a process for assembling microscopic components using magnetic polarity and attraction. The aim is to conduct basic research into the processes of assembling multiple components in a shorlt time. First, the components are positioned tentatively by generating torque in the components due to magnetic polarity. After being positioned accurately by means of the tapers, the components can be connected mechanically and electrically. To study the validity of this concept, an assembly test was conducted. Bonding elements and assembly test equipment were fabricated for this test in order to examine the positioning accuracy achieved when the components were joined.
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