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Andreas Hierlemann

Publications and source records attributed to Andreas Hierlemann.

5 recordsLinked to original sources
PubMed2004

Single-chip mechatronic microsystem for surface imaging and force response studies.

We report on a stand-alone single-chip (7 x 10 mm) atomic force microscopy unit including a fully integrated array of cantilevers, each of which has an individual actuation, detection, and control unit so that standard atomic force microscopy operations can be performed by means of the chip only without any external controller. The system offers drastically reduced overall size and costs as well as increased scanning speed and can be fabricated with standard complementary metal oxide semiconductor technology with some subsequent micromachining steps to form the cantilevers. Full integration of microelectronic and micromechanical components on the same chip allows for the controlling and monitoring of all system functions. The on-chip circuitry, which includes analog signal amplification and filtering stages with offset compensation, analog-to-digital converters, a powerful digital signal processor, and an on-chip digital interface for data transmission, notably improves the overall system performance. The microsystem characterization evidenced a vertical resolution of < 1 nm and a force resolution of < 1 nN as shown in the measurement results. The monolithic system represents a paradigm of a mechatronic microsystem that allows for precise and fully controlled mechanical manipulation in the nanoworld.

Journal Article↗
PubMed2004

Metal oxide-based monolithic complementary metal oxide semiconductor gas sensor microsystem.

A fully integrated gas sensor microsystem is presented, which comprises for the first time a micro hot plate as well as advanced analog and digital circuitry on a single chip. The micro hot plate is coated with a nanocrystalline SnO2 thick film. The sensor chip is produced in an industrial 0.8-microm CMOS process with subsequent micromachining steps. A novel circular micro hot plate, which is 500 x 500 microm(2) in size, features an excellent temperature homogeneity of +/-2% over the heated area (300-microm diameter) and a high thermal efficiency of 6.0 degrees C/mW. A robust prototype package was developed, which relies on standard microelectronic packaging methods. Apart from a microcontroller board for managing chip communication and providing power supply and reference signals, no additional measurement equipment is needed. The on-chip digital temperature controller can accurately adjust the membrane temperature between 170 and 300 degrees C with an error of +/-2 degrees C. The on-chip logarithmic converter covers a wide measurement range between 1 kOmega and 10 MOmega. CO concentrations in the sub-parts-per-million range are detectable, and a resolution of +/-0.1 ppm CO was achieved, which renders the sensor capable of measuring CO concentrations at threshold levels.

Journal Article↗
PubMed2004

Tuning sensitivity and selectivity of complementary metal oxide semiconductor-based capacitive chemical microsensors.

New details on selectivity and sensitivity of fully integrated CMOS-based capacitive chemical microsensor systems are revealed. These microsystems have been developed to detect volatile organics in ambient air and rely on polymeric sensitive layers. The sensitivity and selectivity changes induced by thickness variation of the sensitive polymer layer allow for tuning of the layer parameters to achieve desired sensor features. Cross-sensitivity to interfering agents can be drastically reduced, as is shown for two important cases: (a). rendering the capacitive sensor insensitive to a low-dielectric-constant analyte (lower than that of the polymer) and (b). reducing the influence of a high-dielectric-constant analyte, such as water, on the sensor response. The second case is of vital importance for capacitive sensors, since water is omnipresent and evokes large capacitive sensor signals. The thickness-induced selectivity is explained as a combination of dielectric constant change and swelling and has been confirmed by measurements. Experimentally determined sensitivities qualitatively and quantitatively coincide with the calculated values implying understanding of the sensing mechanism.

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PubMed2002

Complementary metal oxide semiconductor cantilever arrays on a single chip: mass-sensitive detection of volatile organic compounds.

The sensing behavior of polymer-coated resonant cantilevers for mass-sensitive detection of volatile organic compounds was investigated. Industrial complementary metal oxide semiconductor (CMOS) technology combined with subsequent CMOS-compatible micromachining was used to fabricate a single-chip system comprising the transducers and all necessary driving and signal-conditioning circuitry. An analytical model was developed to describe the mass-sensing mechanism of polymer-coated resonant cantilevers. The model was validated by measurements of various gaseous analytes. As an exemplary application, the quantitative analysis of a binary mixture using an array of four cantilevers is described. Experimental results are given for the concentration prediction of a mixture of n-octane and toluene. Finally, it was established that the limit of detection achieved with cantilever sensors is comparable to that of other acoustic wave-based gas sensors.

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