Selected examples of intelligent (micro) sensor systems: state-of-the-art and tendencies

Abstract

The capability of intelligent sensors to have more intelligence built into them continues to drive their application in areas including automotive, aerospace and defense, industrial, intelligent house and wear, medical and homeland security. In principle it is difficult to overestimate the importance of intelligent (micro) sensors or sensor systems within advanced societies but one characteristic feature is the global market for sensors, which is now about $20 billion annually. Therefore sensors or sensor systems play a dominant role in many fields from the macro sensor in manufacturing industry down to the miniaturized sensor for medical applications. The diversity of sensors precludes a complete description of the state-of-the-art; selected examples will illustrate the current situation. MEMS (microelectromechanical systems) devices are of special interest in the context of micro sensor systems. In past the main requirements of a sensor were in terms of metrological performance. The electrical (or optical) signal produced by the sensor needed to match the measure relatively accurately. Such basic functionality is no longer sufficient. Data processing near the sensor, the extraction of more information than just the direct sensor information by signal analysis, system aspects and multi-sensor information are the new demands. A shifting can be observed away from aiming to design perfect single-function transducers and towards the utilization of system-based sensors as system components. In the ideal case such systems contain sensors, actuators and electronics. They can be realized in monolithic, hybrid or discrete form—which kind is used depends on the application. In this article the state-of-the-art of intelligent sensors or sensor systems is reviewed using selected examples. Future trends are deduced.

pH-dependent adsorption of Au nanoparticles on chemically modified Si3N4MEMS devices

“…Microelectromechanical systems (MEMS) devices are defined by the integration of electrical and mechanical components on the micron length scale [1]. Examples of the use of MEMS devices include actuators [2,3] and sensors [4][5][6][7][8][9][10][11][12][13][14]. MEMS devices can be used as chemical sensors via mass detection [7,14], whereby the resonant frequency of a MEMS resonator changes upon the adsorption of chemical species; the resultant change of resonant frequency is proportional to the mass adsorbed on the surface [4,7,15].…”

Overview of Micro-Manufacturing

“…are the new demands [56]. Their applications in micro-manufacturing such as that in equipment and that for online inspection require high levels of accuracy/resolution of the sensors.…”

Solid State Chemical Sensors: Technologies and Applications

“…Although both MOS and conducting polymer sensors can be reversibly responsive to ammonia, the former require elevated temperatures of around 400-550 °C to function correctly, detecting adsorbed decomposition by-products, whilst the latter have a direct response to the analyte of interest, at or near ambient temperature. Recent advances in low power, large scale integrated (LSI) micro-electronics enables "smart-sensor" modules to have a greater degree of autonomy via local signal conditioning and increased data storage capacity (11)(12)(13). Thus, it is now a practical proposition to construct small multi-sensor, data acquisition modules for use in distributed, large area gas sensing systems.…”