CPC G01N 27/223 (2013.01) [G01D 5/24 (2013.01); G01N 27/221 (2013.01); G01N 27/226 (2013.01); G01N 27/228 (2013.01)] | 16 Claims |
1. A capacitive sensor comprising
a substrate;
an electrode structure comprising
at least a first electrode and a second electrode; and
a sensing layer arranged between the first electrode and the second electrode; and
a measurement circuit configured to
measure the capacitance of the electrode structure by
applying, at a first measurement stage, a first pair of electrical potentials comprising a first electrical potential of the first electrode applied to the first electrode and a first electrical potential of the second electrode applied to the second electrode; and
applying, at a second measurement stage, a second pair of electrical potentials comprising a second electrical potential of the first electrode applied to the first electrode and a second electrical potential of the second electrode applied to the second electrode;
wherein
the first electrical potential of the second electrode and the second electrical potential of the second electrode are different from each other; wherein
the first pair of electrical potentials and the second pair of electrical potentials are applied such that
0<(VA1−VA2)<=(VB2−VB1)*CBE/CAE; or
(VB2−VB1)*CBE/CAE<=(VA1−VA2)<0
wherein
VA1 is the first electrical potential of the first electrode at the first measurement stage;
VA2 is the second electrical potential of the first electrode at the second measurement stage;
VB1 is the first electrical potential of the second electrode at the first measurement stage;
VB2 is the second electrical potential of the second electrode at the second measurement stage;
CAE is a capacitance between the first electrode and a virtual electrode arranged on the surface of the sensing layer; and
CBE is a capacitance between the second electrode and the virtual electrode arranged on the surface of the sensing layer.
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