TECHNOLOGY FOCUS - CERAMICS AND GLASS - Preferred Materials: The planar structure is made of glass and/or ceramic.    TECHNOLOGY FOCUS - ELECTRONICS - Preferred Components: The thermally isolating structure comprises at least two layers formed in a manner that minimizes tension in the thermally isolating structure. It may be a folded structure including fold(s). The folded structure may include a first section, a folding section, and a second section folded back and parallel to the first section to form a U-shaped structure. The thermally isolating structure is coupled to the device substrate and support structure at multiple locations. Electrical trace(s) is disposed on the thermally isolating structure and device substrate. Microfluidic channel(s) and/or micro-electromechanical device(s) may be disposed on the device substrate. Active device(s), e.g. transistor(s) may be disposed on the device substrate. A vacuum device comprising an electron emitter may be disposed on the device substrate. The support structure is provided with an aperture, and the device substrate is disposed within the aperture forming a planar structure between the support structure and device substrate. An annular structure is disposed between the device substrate and support structure. The device substrate may be disposed over the support structure. It may be provided with a light reflective surface or a light-absorbing surface. The support structure has a support attachment surface including a support attachment surface normal, and the device substrate has a substrate attachment surface including a substrate attachment surface normal. The thermally isolating structure attaches to the device substrate at a first predetermined angle to the substrate attachment surface normal and to the support at a second predetermined angle to the support attachment surface normal. The support structure, device substrate, and thermally isolating structure are made from the same material. A package (110) encloses the device substrate. The package is sealed at a pressure below atmospheric pressure and reduces convective thermal transfer from the device substrate. It comprises a vacuum portion, a fluid flow portion, and a radiation-reflecting surface. An outer vacuum package encloses a reflecting surface or reflector interposed between the device substrate and a cover or lid. The reflector has a metal surface. The package provides fluid flow. Preferred Dimensions: The thermally isolating structure has a cross-sectional area having uniform thermal coefficient of expansion and uniform composition of matter. The cross-sectional area of thermally isolating structure may vary. The thermally isolating structure has a thickness that varies.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Materials: The planar structure may be made of silicon, gallium arsenide, germanium, indium phosphide, and/or metals.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Materials: The planar structure may be made of silicon, gallium arsenide, germanium, indium phosphide, and/or metals.    TECHNOLOGY FOCUS - POLYMERS - Preferred Materials: The planar structure may be made of polymer(s).