Pressure sensing element including electrode having protrusion
A pressure sensing element according to one aspect of the present disclosure includes a first electrode including at least one protrusion, a second electrode facing the at least one protrusion, and a dielectric disposed between the first electrode and the second electrode. The dielectric includes a first dielectric and a second dielectric. The first dielectric is disposed between a top of the at least one protrusion and the second electrode, and is in contact with each of the top of the at least one protrusion and the second electrode. The second dielectric is disposed between a first portion of the first electrode and the first dielectric. The first portion does not include the at least one protrusion. The at least one protrusion has a higher elastic modulus than the first dielectric.
1. A pressure sensing element comprising:
a first electrode including at least one protrusion;
a second electrode facing the at least one protrusion; and
a dielectric disposed between the first electrode and the second electrode, the dielectric including a first dielectric and a second dielectric, wherein
the first dielectric is disposed between a top of the at least one protrusion and the second electrode, and is in contact with each of the top of the at least one protrusion and the second electrode,
the second dielectric is disposed between a protrusion-free portion of the first electrode and the first dielectric, the protrusion-free portion not including the at least one protrusion,
the at least one protrusion has a higher elastic modulus than the first dielectric,
the pressure sensing element has a capacitance including a first capacitance and a second capacitance,
the first capacitance is a capacitance of a first capacitor including a contact area between the at least one protrusion and the first dielectric, and
the second capacitance is a capacitance of a second capacitor including a contact area between the first dielectric and the second dielectric.
2. The pressure sensing element according to claim 1 , wherein the first dielectric has flexibility.
3. The pressure sensing element according to claim 1 , wherein the second dielectric is configured such that a thickness of the second dielectric decreases when the first dielectric is flexurally deformed by a load applied to the pressure sensing element.
4. The pressure sensing element according to claim 1 , wherein the first dielectric has elasticity.
5. The pressure sensing element according to claim 1 , wherein a capacitance characteristic of the pressure sensing element has a higher linearity than that of the first capacitance and that of the second capacitance.
6. The pressure sensing element according to claim 1 , wherein the first capacitor includes the at least one protrusion, a first section of the second electrode facing the at least one protrusion, and a part of the first dielectric positioned between the at least one protrusion and the first section of the second electrode, and
the second capacitor includes the protrusion-free portion of the first electrode, a second section of the second electrode facing the protrusion-free portion of the first electrode, a part of the first dielectric positioned between the protrusion-free portion of the first electrode and the second section of the second electrode, and the second dielectric.
7. The pressure sensing element according to claim 1 , wherein the at least one protrusion has a tapered shape in which a width of the at least one protrusion gradually decreases toward the second electrode.
8. The pressure sensing element according to claim 1 , wherein at least one selected from the group of the first electrode, the second electrode, the first dielectric, and the second dielectric has light transmissivity.
9. The pressure sensing element according to claim 1 , further comprising a supporting member and a pressing member, wherein
the first electrode has a first main surface facing the second electrode and a second main surface opposite the first main surface,
the second electrode has a third main surface facing the first electrode and a fourth main surface opposite the third main surface,
the supporting member is in contact with the second main surface, and
the pressing member is in contact with the fourth main surface.
10. The pressure sensing element according to claim 1 , further comprising a spacer disposed between the first electrode and the second electrode.
11. The pressure sensing element according to claim 1 , wherein the first dielectric is configured to allow at least one portion of the at least one protrusion to penetrate into the first dielectric and configured to such that a contact area between the at least one protrusion and the first dielectric increases due to the penetration when a load is applied to the pressure sensing element.
12. The pressure sensing element according to claim 11 , wherein the second dielectric is configured such that a thickness of the second dielectric decreases when the at least one portion of the at least one protrusion penetrates into the first dielectric by the application of the load to the pressure sensing element.