Systems, Methods, and Devices for Using Passive Pressure Sensors to Measure Pressure at an Inaccessible Location

Abstract

In some embodiments, systems, methods and devices for using passive pressure sensors to measure pressure at an inaccessible location are provided. In some embodiments, a system for determining pressure in a ventriculoperitoneal shunt implanted in a subject is provided, the system comprising: an acoustic source emitting signals over a range of frequencies; the ventriculoperitoneal shunt, comprising: a lumen that provides a conduit for cerebrospinal fluid between; and a passive acoustic element in a wall of the ventriculoperitoneal shunt filled with a gas, wherein the passive acoustic element emits a second signal at a resonant frequency that varies based on the pressure on the passive acoustic element; an acoustic receiver that detects the second signal and outputs an electrical signal that represents at least the resonant frequency; and a processor programmed to: receive the electrical signal; determine the pressure using the resonant frequency; and present the pressure using a display.

1 .- 12 . (canceled) 
     
     
         13 . A passive pressure sensor device, comprising:
 a plurality of passive acoustic elements that each emits a response signal at a resonant frequency in response to receiving an applied signal at the resonant frequency, wherein the value of the resonant frequency varies based on the pressure on the passive acoustic element emitting the second signal;   a first material filling each of the plurality of passive acoustic elements; and   a second material surrounding the first material of each of the plurality of passive acoustic elements.   
     
     
         14 . The passive pressure sensor device of  claim 13 , wherein the first material comprises primarily a gas. 
     
     
         15 . The passive pressure sensor device of  claim 14 , wherein the gas comprises primarily nitrogen gas. 
     
     
         16 . The passive pressure sensor device of  claim 14 , wherein the gas comprises primarily sulfur hexafluoride gas. 
     
     
         17 . The passive pressure sensor device of  claim 14 , wherein each of the plurality of passive acoustic elements have substantially the same dimensions, and the value for the second frequency emitted by each of the plurality of passive acoustic elements is substantially the same. 
     
     
         18 . The passive pressure sensor device of  claim 13 , wherein the resonant frequency is in the acoustic range. 
     
     
         19 . The passive pressure sensor device of  claim 13 , wherein the value of the resonant frequency increases as pressure on the passive acoustic element increases. 
     
     
         20 . The passive pressure sensor device of  claim 13 , wherein the surrounding material is a compliant material.