Pressure sensors for small-scale applications and related methods

Abstract

Certain pressure sensor devices are much smaller than prior art devices, yet are at least as sensitive as the prior art devices. A capacitive pressure sensor can include a flexible substrate that permits bending of a pressure sensing region without significantly affecting operation thereof. The pressure sensor can include a flexible membrane in which an electrode is sandwiched between two layers of polymeric material. The sandwiched electrode can be extremely close to a reference electrode so as to provide for highly sensitive capacitance readings, yet the membrane can be restricted from contacting the reference electrode under high pressure condition.

1 . A capacitive pressure sensor for monitoring fluid pressure within a patient, the pressure sensor comprising:
 a substrate;   a first electrode in abutting contact with the substrate;   a membrane spaced from the first electrode, wherein the membrane comprises:
 a second electrode configured to be displaced toward the first electrode; and 
 at least one flexible layer covering at least a portion of the second electrode; and 
   a dielectric region between the first electrode and the membrane,   wherein the pressure sensor has a sensitivity of no less than about 0.3 fF/mmHg.   
     
     
         2 . The pressure sensor of  claim 1 , wherein the second electrode is thinner than the at least one flexible layer so as to readily bend when the at least one flexible layer is bent toward the substrate. 
     
     
         3 . The pressure sensor of  claim 1 , wherein the second electrode is sandwiched between two flexible layers. 
     
     
         4 . The pressure sensor of  claim 1 , wherein each of the substrate and the at least one flexible layer are polymeric. 
     
     
         5 . The pressure sensor of  claim 1 , wherein the substrate comprises liquid crystal polymer and the at least one flexible layer comprises parylene. 
     
     
         6 . The pressure sensor of  claim 1 , wherein the sensitivity is substantially constant over a range of from about 0 mmHg to about 50 mmHg above atmospheric pressure. 
     
     
         7 . The pressure sensor of  claim 1 , wherein a perimeter of the substrate defines an area of no greater than about 2 millimeters 2 . 
     
     
         8 . The pressure sensor of  claim 1 , further comprising an additional flexible layer covering at least a portion of the first electrode, wherein the additional flexible layer and the at least one flexible layer of the membrane comprise the same material. 
     
     
         9 . The pressure sensor of  claim 1 , wherein the dielectric region comprises a gas. 
     
     
         10 . The capacitive pressure sensor of  claim 1 ,wherein the membrane has a depth of no greater than about 7 microns when the membrane is in an uncompressed position. 
     
     
         11 . The pressure sensor of  claim 1 , wherein the substrate is flexible so as to be able to conform to a curved surface. 
     
     
         12 . The pressure sensor of  claim 1 , wherein the pressure sensor has a sensitivity of no less than about 0.3 fF/mmHg whether the substrate is in a flat orientation or a curved orientation. 
     
     
         13 . The pressure sensor of  claim 1 , wherein the first electrode is configured to bend in conformity with the substrate.