A micromachined thermal flow sensor applied to a PC mouse device

This paper reports on a new PC mouse device by the use of the micromachined thermal flow sensors. The proposed mouse contains two small flow sensors mounted in two 10-mm-diameter and 3-mm-depth spaces in order to measure its velocity and direction. When the mouse is moved in a direction, air flow is generated because the air tends to stay where it is. Our sensors can detect the wide range flow speed which enables the mouse speed ranging from hundreds to one mm/s. A ball-type mouse is as big as one´s palm because the mouse needs sufficient weight of a rubber ball to provide friction force. An optical mouse is smaller but it needs a patterned indented surface and sufficient light reflection from the surface of the desktop. The present flow mouse is as small as an optical one and it can work even on a smooth transparent glass. The results indicate that displacement can be measured with in an error ratio +/$2% at 10, 50,100 and 150 mm/s. This error ratio is good enough for this application