High sensitivity passive wireless strain sensor
First Claim
1. An apparatus comprising:
- a first layer having a top and a bottom surface, wherein a plurality of conductive digits are formed on the top surface of the first layer;
a second layer positioned on top of the first layer wherein the second layer defines a opening through the second layer and wherein at least a portion of the conductive digits formed on the top surface of the first layer are exposed by the opening; and
a third layer positioned on top of the second layer so that the opening in the second layer forms a cavity having a continuous and uninterrupted perimeter of said opening and bounded on its bottom by the first layer and on its top by the third layer.
2 Assignments
0 Petitions
Accused Products
Abstract
A high sensitivity strain sensor that utilizes a micro-scale cavity built in a multi-layer structure, with a pair of interdigitalized capacitor incorporated on one of the layers, is described in this document. The device'"'"'s capacitance changes produced by unattended deformations of the cavity can be used to measure the associated strain without using any movable electrodes. The sensor can be remotely energized from a radio frequency wave sent by a reader antenna to construct a battery-free wireless instrument. Changes on the sensor'"'"'s resonant frequency are remotely detected so that a strain level is measured from fluctuations in the received signal. This detection method provides a simple, reliable and sensitive technique to measure small strain changes down to the pico-scale. Materials with a highly strain-dependant permittivity are integrated in the sensor to enhance its sensitivity. The proposed sensor consists of a simple planar structure. It can be used as the main component on low-cost, accurate and highly stable strain measuring instruments capable of monitoring very small strain levels. Furthermore, the sensor is passive, may be operated wirelessly, and can, thus, be used for remote long-term embedded strain detection.
43 Citations
17 Claims
-
1. An apparatus comprising:
-
a first layer having a top and a bottom surface, wherein a plurality of conductive digits are formed on the top surface of the first layer; a second layer positioned on top of the first layer wherein the second layer defines a opening through the second layer and wherein at least a portion of the conductive digits formed on the top surface of the first layer are exposed by the opening; and a third layer positioned on top of the second layer so that the opening in the second layer forms a cavity having a continuous and uninterrupted perimeter of said opening and bounded on its bottom by the first layer and on its top by the third layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. An apparatus comprising:
-
a first layer having a top and a bottom surface, wherein a plurality of conductive digits are formed on the top surface of the first layer; a second layer having a continuous top surface and a continuous bottom surface, said second layer being positioned on top of the first layer wherein the second layer comprises a pass-through opening between its continuous top surface and its continuous bottom surface and wherein at least a portion of the conductive digits formed on the top surface of the first layer are exposed by the pass-through opening; and a third layer positioned on top of the second layer so that the pass-through opening in the second layer forms a cavity bounded on its bottom by the first layer and on its top by the third layer. - View Dependent Claims (10, 11)
-
-
12. An apparatus comprising:
-
a first layer having a top and a bottom surface, wherein a plurality of conductive digits are formed on the top surface of the first layer; a second layer positioned on top of the first layer wherein the second layer defines a opening through the second layer and wherein at least a portion of the conductive digits formed on the top surface of the first layer are exposed by the opening; and a third layer positioned on top of the second layer so that the opening in the second layer forms a cavity bounded on its bottom by the first layer and on its top by the third layer, wherein the second layer has outer dimension matching at least one of;
the outer dimension of the first layer and the outer dimension of the third layer. - View Dependent Claims (13, 14)
-
-
15. A wireless strain sensor comprising:
-
a base substrate; a passive LC circuit including an interdigital capacitor and an inductor formed on said substrate; and an enclosing substrate arrangement positioned on top of said base substrate, wherein in combination with said base substrate provides a sealed cavity enclosing at least a portion of said interdigital capacitor. - View Dependent Claims (16, 17)
-
Specification