Abstract
The development of silicon-based sensor devices has enabled the possibility to pursue novel integrated smart sensor technologies. Under this scenario, capacitive sensor devices are one viable option for implementing different kinds of applications. In this paper, an interdigitated coplanar capacitive device fabricated over a silicon substrate is presented and its potential use as liquid sensor is demonstrated. Additionally, a detailed capacitance model, which includes the parasitic capacitances introduced by the silicon substrate, was developed. The capacitance model has been theoretically validated through finite-element simulations as well as experimentally by comparison with fabricated devices. A polydimethylsiloxane mold has been fabricated and bonded to the sensor device with the aim of defining a cavity to collect the liquid sample into the device’s active region. The active capacitance component correlates to the electric field coupling between adjacent metal lines. Therefore, any change to the dielectric constant of the medium above the coplanar metal lines will produce a change to the device capacitance. Finally, the main guidelines for device performance improvement are depicted.
Highlights
Recent advances in microfabrication technologies have allowed for the possibility to develop novel sensor devices for a variety of applications such as gas sensors, photodetectors, chemical and biological sensors, as well as liquid sensor devices [1,2,3]
Due to the conductivity of the silicon substrate, it will act as a virtual electrode, which will promote an electric coupling with each metal line
These results clearly show that silicon substrate produces an important is improved
Summary
Recent advances in microfabrication technologies have allowed for the possibility to develop novel sensor devices for a variety of applications such as gas sensors, photodetectors, chemical and biological sensors, as well as liquid sensor devices [1,2,3]. The use of coplanar capacitive structures (CCS) has demonstrated the possibility to implement sensor devices [11,12,13,14,15]. The fabrication of Sensors 2021, 21, 5958 standard digital technology remains an important concern. InIn this contribution, an an interdigitated coplanar capacitive sensor device fabricated on on silicon substrate is presented. The potential application as sensor liquid sensor is demonstrated, andsilicon substrate impact isimpact addressed. Schematic structure is shown, and the basic cell of the device is defined; (b) An image of the fabricated device over a silicon substrate with 200 μm metal width; (c) The physical device implantation for liquid sensor applications
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