US 11,726,052 B2
Capacitive sensor
Marcel Plüss, Stäfa (CH)
Assigned to Sensirion AG, Stäfa (CH)
Appl. No. 17/431,480
Filed by Sensirion AG, Stäfa (CH)
PCT Filed Feb. 19, 2020, PCT No. PCT/EP2020/054379
§ 371(c)(1), (2) Date Aug. 17, 2021,
PCT Pub. No. WO2020/169676, PCT Pub. Date Aug. 27, 2020.
Claims priority of application No. 19158447 (EP), filed on Feb. 21, 2019.
Prior Publication US 2022/0136991 A1, May 5, 2022
Int. Cl. G01R 27/26 (2006.01); G01N 27/22 (2006.01); G01D 5/24 (2006.01)
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
OG exemplary drawing
 
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.