Capacitive sensing at long ranges (10x the plate diameter) for long-term environmental monitoring can be limited by slow but significant measurement drifts from charge induction, which can exceed the small capacitance variations of interest, below 0.01 %. This paper proposes a slope modulation differential capacitance measurement method for single-plate capacitive sensors operating in loading mode that effectively rejects noise from quasi-constant drift currents. It is based on periodical plate capacitance charge-discharge, like the period modulation frontends (astable multivibrators) that were used in past work, but it uses a constant oscillation period and compares the slopes of adjacent plate voltage ramps. Plate capacitance is calculated by averaging the slope magnitudes, which rejects the noise from quasi-constant drift currents. The sensitivity and noise rejection are compared with the period modulation techniques analytically, and the results are validated using simulations and experiments. They show that human body sensing range doubles and the noise floor is substantially lower compared to the state-of-the-art (period modulation).
Drift Rejection Differential Frontend for Single Plate Capacitive Sensors / Subbicini, Giorgia; Lavagno, Luciano; Lazarescu, Mihai T.. - In: IEEE SENSORS JOURNAL. - ISSN 1530-437X. - ELETTRONICO. - 22:16(2022), pp. 16141-16149. [10.1109/JSEN.2022.3189031]
Drift Rejection Differential Frontend for Single Plate Capacitive Sensors
Giorgia Subbicini;Luciano Lavagno;Mihai T. Lazarescu
2022
Abstract
Capacitive sensing at long ranges (10x the plate diameter) for long-term environmental monitoring can be limited by slow but significant measurement drifts from charge induction, which can exceed the small capacitance variations of interest, below 0.01 %. This paper proposes a slope modulation differential capacitance measurement method for single-plate capacitive sensors operating in loading mode that effectively rejects noise from quasi-constant drift currents. It is based on periodical plate capacitance charge-discharge, like the period modulation frontends (astable multivibrators) that were used in past work, but it uses a constant oscillation period and compares the slopes of adjacent plate voltage ramps. Plate capacitance is calculated by averaging the slope magnitudes, which rejects the noise from quasi-constant drift currents. The sensitivity and noise rejection are compared with the period modulation techniques analytically, and the results are validated using simulations and experiments. They show that human body sensing range doubles and the noise floor is substantially lower compared to the state-of-the-art (period modulation).File | Dimensione | Formato | |
---|---|---|---|
Drift_Rejection_Differential_Frontend_for_Single_Plate_Capacitive_Sensors.pdf
accesso aperto
Descrizione: Main Article
Tipologia:
2a Post-print versione editoriale / Version of Record
Licenza:
Creative commons
Dimensione
2.63 MB
Formato
Adobe PDF
|
2.63 MB | Adobe PDF | Visualizza/Apri |
Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/11583/2970213