In high-temperature applications, such as pressure sensing in turbine engines and compressors, high-temperature materials and data retrieval methods are required. The microelectronics packaging infrastructure provides high-temperature ceramic materials, fabrication tools, and well-developed processing techniques that have the potential for applicability in high-temperature sensing. Based on this infrastructure, a completely passive ceramic pressure sensor that uses a wireless telemetry scheme has been developed. The passive nature of the telemetry removes the need for electronics, power supplies, or contacts to withstand the high-temperature environment. The sensor contains a passive LC resonator comprised of a movable diaphragm capacitor and a fixed inductor, thereby causing the sensor resonant frequency to be pressure-dependent. Data is retrieved with an external loop antenna. The sensor has been fabricated and characterized and was compared with an electromechanical model. It was operated up to 400 C in a pressure range from 0 to 7 Bar. The average sensitivity and accuracy of three typical sensors are: 141 kHz Bar 1 and 24 mbar, respectively.

We explore the use of air trenches to achieve compact high efficiency 90 degrees waveguide bends and beamsplitters for waveguide material systems that have low refractive index and low refractive index contrast between the core and clad materials. For a single air interface, simulation results show that the optical efficiency of a waveguide bend can be increased from 78.4% to 99.2% by simply decreasing the bend angle from 90 degrees to 60 degrees . This can be explained by the angular spectrum of the waveguide mode optical field. For 90 degrees bends we use a micro-genetic algorithm (GA) with a 2-D finite difference time domain (FDTD) method to rigorously design high efficiency waveguide bends composed of multiple air trenches. Simulation results show an optical efficiency of 97.2% for an optimized bend composed of three air trenches. Similarly, a single air trench can be designed to function as a 90 degrees beamsplitter with 98.5% total efficiency.

A skin structure exhibiting flexibility, self-healing and damage sensing has been designed, fabricated and tested. The skin is fabricated on a substrate of copper-clad polyimide sheets in a layer-by-layer technique using polyimide sheets and an ultraviolet (UV)-curable epoxy. The UV-curable epoxy is used as both a structural adhesive and as the self-healing fill material. The skin structure is integrated with an array of LC circuits, where each circuit is characterized by a unique resonant frequency. If the skin is damaged, the UV-curable epoxy is released and is cured by ambient sunlight. Further, damage affects one or more of the LC circuits, altering its resonant frequency. An integrated antenna coil is used to detect and locate the damaged portion of the skin. A proof-of-concept skin is presented which includes a 2 × 2 array of LC circuits. Tests indicate good performance with respect to self-healing of the skin and fault isolation.

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