Short Term Innovative Research on Sensors on Flexible Substrates

摘要

This investigation concerns the development of microsensors sensors on flexible substrates such as Kapton (pyromellitic dianhydride and 4,4' diaminodphenyl ether). Microbolometers have been used as the test bed for microsensor development. The results on this investigation will form a basis for the production of other micromachined sensors such as pressure/strain sensors, 'hair-like' touch and flow sensors, and accelerometers on flexible substrates. Flexible substrates can serve as the basis of a sensitive skin for humans and robots where sensors are distributed over skin to provide the sense of touch and feel or monitor the physiology of the wearer. Two techniques have been investigated. One involves attaching a Kapton film to a 4 inch wafer carrier with an adhesive and the other involves using a spin-on polyimide (Kapton-like) to coat a silicon wafer that has been covered with a release layer. The use of 4 inch wafers permits the use of standard microfabrication equipment. Using these techniques, YBaCuO microbolometers have been fabricated. Low temperature fabrication techniques are employed to minimize the thermal cycling of the polyimide substrate. In our preliminary work, the microbolometers displayed a Temperature Coefficient of Resistance of -3.1 %, at room temperature. The microbolometers reached responsivity and detectivity as high as 6x10(exp 3) V/W and 3x10(exp 7) cm.Hz(sup 1/2)/W, respectively, at 1.85 mu alpha of current bias. This detectivity is approximately 40% of the temperature fluctuation limit for these detectors.