Fabrication and testing of subminiature multi-sensor hot-wire probes

A method for the fabrication of hot-wire sensors measuring 0.6 micron in diameter and 200 microns in length is described. This method allows accurate control of sensing-element orientation, thus making it possible to produce multisensor probes. Test results obtained with a miniature sensor fabricated by this method, for the outer region of a turbulent boundary layer developing in a zero presure gradient were compared to measurements from a conventional-sized probe made in the same flow, demonstrating that, because of their improved spatial resolution, subminiature sensors can provide more accurate measurements in boundary layers than do the conventional probes.