Partner und Internationale Organisationen
(Englisch)
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Motech GmbH (D), Austria Mikrosysteme International AG (A), COPRECI S. COOP. Ltda (E), GASTAR SRL (RO), Filterwerk Mann & Hummel GmbH (D), Robert Seuffer GmbH & Co (D), University of Barbelona (E), University of Tübingen (D)
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Abstract
(Englisch)
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The general objective of this project is to develop a completely novel generation of miniaturized hybrid gas sensor systems fabricated in industrial CMOS technology. The integrated microsensor system relies on conductivity changes of a semiconducting material upon gas absorption. To that end conductivity measurement configurations are designed on arrays of CMOS micromachined heated membranes (microhotplates). Gas-sensitive nanocrystalline tin dioxide is then deposited on the membranes. For optimum cost-efficiency and reliability, the complete sensor sytem is realized as a one-chip-solution in CMOS technology. This allows for integrating the potentiostats, thermoregulation, signal evaluation and processing units on the same chip in immediate vicinity to the array, and for additionally implementing smart features. In close co-operation with the industry partners, the system will be used in the following key-applications: (1) monitoring of residual oil in compressed air, (2) surveillance of food quality in refrigerators, and (3) monitoring of air quality and workplace safety in households and industry. The target analytes comprise carbon monoxide, hydrogen, nitrogen oxide and other inorganic gases.
ETHZ is in charge of the design of the microtransducers and microelectronics of the single-chip-system. The main activities in this task comprise the design of integrated chemical sensor platforms, which are compatible with the silicon IC technology and meet the application needs. Modeling sensor operation and supports the optimization and characterization procedure. The transducer design comprises a conductivity measurement configuration, temperature sensors, and heating resistors on a membrane. The chip further includes driving circuitry for the heating resistors, potentiostats, current amplifiers, signal processing circuitry and a standard interface (I2C). Depending on the required system functionality, the design will result in a single or an array-type architecture.
The third regular chip design was designed and processed at AMS, the fourth design is under processing at the moment. Main activities included full testing of the second and third design, which constitute the final prototype chip. Novel electrode materials were tested (Au, Pt, Rh) and a deposition strategy on wafer level ewas developed. A novel circular hotplate shape leading to less power consumption was sucessfully tested. Digital interface circuitry was redesigned to allow for bus-type operation of the sensor devices, the tests showed improved results. Gas tests with carbon monoxide revealed, that the sensors are quite stable and exhibit better sensitivity than most commercially available devices.
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