Sensors 2012, 12(8), 10550-10565; doi:10.3390/s120810550
Article

Numerical Investigations on Electric Field Characteristics with Respect to Capacitive Detection of Free-Flying Droplets

Received: 11 June 2012; in revised form: 17 July 2012 / Accepted: 25 July 2012 / Published: 3 August 2012
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany 2012)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: In this paper a multi-disciplinary simulation of a capacitive droplet sensor based on an open plate capacitor as transducing element is presented. The numerical simulations are based on the finite volume method (FVM), including calculations of an electric field which changes according to the presence of a liquid droplet. The volume of fluid (VOF) method is applied for the simulation of the ejection process of a liquid droplet out of a dispenser nozzle. The simulations were realised using the computational fluid dynamic (CFD) software CFD ACE+. The investigated capacitive sensing principle enables to determine the volume of a micro droplet passing the sensor capacitor due to the induced change in capacity. It could be found that single droplets in the considered volume range of 5 nL < Vdrop < 100 nL lead to a linear change of the capacity up to ΔQ < 30 fC. The sensitivity of the focused capacitor geometry was evaluated to be Si = 0.3 fC/nL. The simulation results are validated by experiments which exhibit good agreement.
Keywords: droplet sensor; CFD simulation; capacitive measurement; multi physics simulation; non-contact sensor; online process control
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MDPI and ACS Style

Ernst, A.; Mutschler, K.; Tanguy, L.; Paust, N.; Zengerle, R.; Koltay, P. Numerical Investigations on Electric Field Characteristics with Respect to Capacitive Detection of Free-Flying Droplets. Sensors 2012, 12, 10550-10565.

AMA Style

Ernst A, Mutschler K, Tanguy L, Paust N, Zengerle R, Koltay P. Numerical Investigations on Electric Field Characteristics with Respect to Capacitive Detection of Free-Flying Droplets. Sensors. 2012; 12(8):10550-10565.

Chicago/Turabian Style

Ernst, Andreas; Mutschler, Klaus; Tanguy, Laurent; Paust, Nils; Zengerle, Roland; Koltay, Peter. 2012. "Numerical Investigations on Electric Field Characteristics with Respect to Capacitive Detection of Free-Flying Droplets." Sensors 12, no. 8: 10550-10565.

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