Sensor assembly, method, and device for monitoring shear force and pressure on a structure
Shear force and pressure on a structure are simultaneously monitored using signals received from sensors with antennas on the structure. For example, sensors and systems for monitoring shear force and pressure have applications including ulcer prevention associated with structures including shoes, prosthetics, wheel-chairs, and beds of bed-bound patients.
1. An antenna sensor assembly, comprising:
a first structure and a second structure, wherein the first structure is connected to and spaced apart from the second structure by an intermediate structure;
wherein the intermediate structure is configured to allow the first structure to displace laterally relative to the second structure in a first direction in response to a shear force;
the first structure comprising a reflector, wherein the reflector comprises a conductive material and a reflector area; and
the second structure comprising a patch antenna, wherein the patch antenna comprises:
a radiation patch that radiates an electromagnetic wave, the radiation patch comprising an antenna area;
a dielectric substrate; and
a ground plane;
wherein an overlapping area is a portion of the antenna area that is overlapped by the reflector area; and
wherein the patch antenna and the reflector are configured such that resonant frequencies of the antenna sensor assembly are based on a position of the reflector with respect to the patch antenna; and
wherein lateral displacement of the first structure relative to the second structure in response to a shear force shifts a lateral position of the reflector relative to the patch antenna and thereby changes a size of the overlapping area.
2. The antenna sensor assembly of claim 1 , wherein the resonant frequencies of the antenna sensor assembly are based on the overlapping area.
3. The antenna sensor assembly of claim 1 , wherein the intermediate structure is configured to allow the first structure to displace vertically relative to the second structure;
wherein vertical displacement of the second structure relative to the first structure shifts a vertical position of the reflector relative to radiation patch; and
wherein the patch antenna and the reflector are configured such that resonant frequencies of the antenna sensor assembly are further based on a vertical position of the reflector with respect to the patch antenna.
4. The antenna sensor assembly of claim 1 , wherein the reflector is a metallic reflector.
5. The antenna sensor assembly of claim 4 , wherein the metallic reflector is shaped and positioned such that when the first structure is not displaced:
the reflector area overlaps a first edge of the antenna area; and
at least a second edge of the antenna area is at least in part not overlapped by the reflector area.
6. The antenna sensor assembly of claim 5 , wherein the reflector area overlaps a third edge of the patch antenna.
7. The antenna sensor assembly of claim 6 , wherein the reflector area overlaps a fourth edge of the antenna area.
8. The antenna sensor assembly of claim 6 , wherein a fourth edge of the antenna area is at least in part not overlapped by the reflector area.
9. The antenna sensor assembly of claim 1 , wherein the reflector area includes a first strip that extends longitudinally in a second direction, wherein the second direction is perpendicular to the first direction.
10. The antenna sensor assembly of claim 9 , wherein the reflector area includes a second strip that extends longitudinally in the first direction.
11. The antenna sensor assembly of claim 1 , wherein the reflector area has a shape that is one of a strip, an L-shape, an I-shape, a U-shape, and a cross-shape.
12. The antenna sensor assembly of claim 1 , wherein a shape of the reflector area at least partially defines a shape of a non-reflector area of the first structure.
13. The antenna sensor assembly of claim 12 , wherein a non-overlapping area is a portion of the antenna area that is overlapped by the non-reflector area.
14. The antenna sensor assembly of claim 13 , wherein the shape of the non-reflector area has a shape that is one of a slot, a strip, and a cross-shape.
15. The antenna sensor assembly of claim 1 , wherein the intermediate structure is a spacer that is configured to prevent the first structure from displacing laterally relative to the second structure in a second direction in response to a shear force, wherein the first direction is perpendicular to the second direction.
16. The antenna sensor assembly of claim 15 , wherein the first structure includes a first rigid frame and the second structure includes a second rigid frame; and
wherein the first rigid frame includes a first slot that is configured to receive the reflector and the second rigid frame includes a second slot that is configured to receive the patch antenna.
17. The antenna sensor assembly of claim 1 , wherein the intermediate structure is a dielectric substrate.