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%0 Thesis %A Li, Ji %T Alternative acceleration sensors from polymers %C Aachen %I Publikationsserver der RWTH Aachen University %M RWTH-CONV-126645 %P V, 105 S. : Ill., graph. Darst. %D 2012 %Z Zsfassung in dt. und engl. Sprache %Z Aachen, Techn. Hochsch., Diss., 2012 %X Usually micro machined acceleration sensors are silicon-based. There are two conspicuous advantages of employing silicon technology: firstly, the mechanical element of the sensor can be integrated with the electronics required for signal processing; secondly, silicon-based micromachining technologies are capable of reducing the size of a sensor device to the micrometer. Nowadays, integrating electronics into polymer substrates has been realized, which means that polymer devices in future could be integrated with electronics as well. Therefore, the feasibility of fabricating acceleration sensors from polymer is investigated in this dissertation. The fabrication of micro systems from polymer is expected to be even more economic than from silicon. Since polymers tend to creep and their properties are a strong function of temperature, polymer components appear to be not suitable functional elements in a sensor. Accordingly, two methods were proposed to avoid this disadvantage: on the one hand, the principles of thermal flow sensors can be adopted to design acceleration sensors, which apply thermal components instead of a proof mass and a suspending system as the sensing elements; on the other hand, applying a closed feedback loop balancing the inertial force such, that the dependence on mechanical properties and temperature of the sensing element is limited significantly. For the thermal method, two designs, an anemometer and a calorimeter, were investigated and fabricated by micro milling and micromachining. Compared with the anemometric design, the calorimetric sensor has three outstanding advantages, such as higher sensitivity, a linear characteristic curve and direction sensing capability, which make it a good choice for an alternative acceleration sensor. In the experiments, the calorimeter achieved a sensitivity of 0.5 V/(m/s²) when the power of the heater is 0.2 W. For the closed loop method three types of driving modes, capacitive, thermo-pneumatic, and electromagnetic, were proposed and tested. In the research, the capacitive and thermo-pneumatic modes showed only theoretical feasibility, but no working sample could be realized due to the available equipments. The magnetic mode successfully fulfilled its function. In this case the acceleration is balanced by an electromagnetic force of a coil in the field of permanent magnets and the electrical current necessary for balancing is a measure of the acceleration. Both micromachining and mechanical manufacturing processes, such as sputtering, photolithography, and ultrasonic hot embossing were employed in the fabrication of the magnetic closed loop acceleration sensor. The sensor was assembled from a polyimide membrane with conductor paths from gold patterned by photolithography and etching, a frame manufactured by ultrasonic hot embossing, and permanent magnets fixed to the frame. Except the conductor path and permanent magnets all components are made of polymers on a planar substrate, and then the frame is kinked forming the desired three-dimensional structure. In tests, a sensitivity of 0.46 V/(m/s²) was achieve, and the cross axis sensitivity error was less than 3 %K Beschleunigungssensor (SWD) %K Polymere (SWD) %F PUB:(DE-HGF)11 %9 Dissertation / PhD Thesis %U https://publications.rwth-aachen.de/record/65386