Volume 9, Number 1 • January/February 2001

Technology Opportunity Showcase highlights some unique technologies that NASA has developed and which we believe have strong potential for commercial application. While the descriptions provided here are brief, they should provide enough information to communicate the potential applications of the technology.or more detailed information, contact the person listed. Please mention that you read about it in Innovation

Thin Film Heat Flux Sensor

NASA Glenn Research Center is seeking partnerships with industry for aerospace and non-aerospace applications for the purpose of transferring the process for fabricating thin film heat flux sensors. Benefits of the sensors include the fact that they can measure heat flux at temperatures up to 1,700 degrees F; can be fabricated directly on parts without cutting into the part; are minimally intrusive in engines; are of small mass, so high frequency measurements can be made; provide accurate knowledge of heat loading on critical propulsion system components; and can measure heat fluxes up to 88 BTU/ft2 sec. The heat flux sensor has now been incorporated into a multi-function sensor that measures strain magnitude and direction, surface temperature, and heat flux. Potential commercial uses include measuring heat flux incidents on ceramic engine parts and rocket engine parts, measuring heat flux in automotive engines and aircraft engines, measuring furnace output, detecting fires, and for calorimetry.

Heat flux is measured by using temperature sensors (thermocouples) to determine the temperature difference across a test material. This is accomplished by fabricating a thermopile (two or more thermocouples connected in series) on the surface of a material. The thermopile is arranged so that the junctions are in concentric circles. The outer set of thermopile junctions is coated with a thin insulator and the inner one with a thick insulator. Heat passing through the insulators produces a different temperature at each set of junctions. The incident heat flux is directly proportional to this temperature difference. The thin film heat flux sensors are fabricated as a plug-type sensor on the surface of a ceramic material. They can also be fabricated directly on the surface of a part such as a turbine blade. Contact pads for the purpose of making connections to a data system are built into the heat flux sensor. Vacuum radio frequency sputtering technology and photolithography are used to fabricate the sensor. All components are thin films, so the total sensor thickness is in the 0.0004- to 0.004-in. range.

For more information, contact Gus Fralick at Glenn Research Center (216/433-3645) Gustave.C.Fralick@grc.nasa.gov. Please mention you read about it in Innovation.

High-Performance, Durable Actuators for Demanding Applications

NASA Langley Research Center is seeking to license a Macro-Fiber Composite (MFC) technology that is a high-performance, cost-competitive, easily manufactured piezoelectric strain actuator. This proven technology produces controlled motion when stimulated by a driving voltage or generates a potential when strained. The MFC actuator may be embedded in or attached to the surface of a flexible structure for distributed deflection, vibration control and strain sensing. Benefits of the technology include that it is made of commercial, off-the-shelf materials; is flexible, durable and damage-tolerant; conforms to surfaces; and is readily embeddable. It features increased strain actuator efficiency; directional actuation/sensing; low-cost, repeatable manufacturing processes; an environmentally-safe sealed package; and demonstrated performance.

Potential applications include use in helicopters for vibration suppression, rotor blade control and noise reduction; aircraft for buffet alleviation on rudders and air foil shaping; spacecraft for vibration suppression; actuators for shape changing, auto-focusing, structural stiffening and micropositioning; sensors for dynamic structural health monitoring, direct mechanical-to-electrical conversion and accelerometers; and automobiles for speakers, interior noise abatement, braking and speed control.

The actuator is made by slicing a wafer of piezoelectric ceramic into closely spaced rectangular segments by using conventional wafer-dicing methods common to the semiconductor industry. The resulting segmented sheet is sandwiched between layers of adhesive and electroded polyimide film. This film contains interdigitated electrodes to transfer the applied voltage to the piezoelements. This assembly enables in-plane poling-alignment of randomly oriented grains found in the material to a desired electric field, actuation and sensing in a sealed, durable, ready-to-use package.

NASA Langley has filed for patent protection on the MFC manufacturing method and actuator, and offers licensing opportunities for this technology.

For more information, contact Marisol Garcia at NASA Langley Research Center (757/864-5355) m.e.garcia@larc.nasa.gov. Please mention you read about it in Innovation.