Print Email Facebook Twitter A Low-Power, Wireless, Capacitive Sensing Frontend Based on a Self-Oscillating Inductive Link Title A Low-Power, Wireless, Capacitive Sensing Frontend Based on a Self-Oscillating Inductive Link Author Schormans, Matthew (University College London (UCL)) Valente, V. (TU Delft Bio-Electronics; University College London (UCL)) Demosthenous, Andreas (University College London (UCL)) Date 2018 Abstract Wireless sensing systems are becoming popular in a range of applications, particularly in the case of biomedical circuits and food monitoring systems. A typical wireless sensing system, however, may require considerable complexity to perform the necessary analog to digital conversion and subsequent wireless transmission. Alternatively, in the case of inductive link based systems, large, manually operated impedance analyzers are required. Based on a detailed analysis of the link impedance, this paper proposes a simple method for wireless capacitive sensing through an inductive link that uses a self-oscillator and a frequency counter. The method enables changes in capacitance to be sensed and wirelessly transmitted simultaneously. In order to test the effectiveness of the method, a self-oscillating circuit was designed and fabricated in 0.18 μm CMOS, and combined with an on-chip humidity sensing capacitor. The system was tested in a humidity chamber across a range of 20-90%rh. Measured results from the system demonstrate that capacitive changes as small as 28 fF, translating to <2%rh, can be resolved, with a power consumption of 1.44 mW. Subject CapacitanceCapacitive sensinghumidity sensingImpedanceinductive linkMonitoringResonant frequencySensorsWireless communicationwireless sensing.Wireless sensor networks To reference this document use: http://resolver.tudelft.nl/uuid:ac4b641a-b515-4441-a475-a035e03f0a51 DOI https://doi.org/10.1109/TCSI.2018.2835148 ISSN 1549-8328 Source IEEE Transactions on Circuits and Systems Part 1: Regular Papers, 65 (9), 2645-2656 Part of collection Institutional Repository Document type journal article Rights © 2018 Matthew Schormans, V. Valente, Andreas Demosthenous Files PDF 45807921_08409449.pdf 3.51 MB Close viewer /islandora/object/uuid:ac4b641a-b515-4441-a475-a035e03f0a51/datastream/OBJ/view