Implantable sensor housing, sensor unit and methods for forming and using the same

Abstract

An in vivo implantable sensor unit includes a glass sensor housing defining an elongated chamber. Sensor electronics are disposed in the chamber. The sensor electronics are adapted to wirelessly transmit data. The sensor unit is configured to wirelessly transmit data from an in vivo position to a remote receiver over a period of at least four weeks and the sensor housing is adapted to provide a hermetic seal about the sensor electronics for a period of at least four weeks. The hermetic seal is such that under a helium mass spectrometer leak detection test the sensor housing has a leak rate that is less than about 10 −8 atm-cc/s.

That which is claimed is:  
     
         1 . An in vivo implantable sensor unit comprising: 
 a) a glass sensor housing defining an elongated chamber; and    b) sensor electronics disposed in the chamber, wherein the sensor electronics are adapted to wirelessly transmit data;    c) wherein the sensor unit is configured to wirelessly transmit data from an in vivo position to a remote receiver over a period of at least four weeks and the sensor housing is adapted to provide a hermetic seal about the sensor electronics for a period of at least four weeks, wherein the hermetic seal is such that under a helium mass spectrometer leak detection test the sensor housing has a leak rate that is less than about 10 −8  atm-cc/s.    
     
     
         2 . The sensor unit of  claim 1  wherein the sensor electronics include a first portion and a second portion joined to the first portion at a junction, the sensor unit further including an epoxy disposed in the chamber and surrounding the junction, wherein the epoxy mechanically stabilizes the first and second portions.  
     
     
         3 . The sensor unit of  claim 2  wherein the sensor housing has a length of no more than 27 mm and an outer diameter of no more than 3.5 mm.  
     
     
         4 . An implantable sensor unit comprising: 
 a) a tube defining a chamber and an opening communicating with the chamber;    b) sensor electronics disposed in the chamber;    c) epoxy disposed in the chamber and surrounding the sensor electronics, the epoxy having an end surface adjacent the opening of the tube; and    d) an end plug mounted in the opening of the tube;    e) wherein the end surface of the epoxy and the end plug define a gap therebetween configured to insulate the sensor electronics.    
     
     
         5 . An implantable sensor unit comprising: 
 a) a tube defining an elongated chamber and an opening communicating with the chamber;    b) sensor electronics disposed in the chamber; and    c) an end plug mounted in the opening of the tube, wherein the end plug is spherically shaped.    
     
     
         6 . The sensor of  claim 5  including epoxy disposed in the chamber and surrounding the sensor electronics, the epoxy having an end surface adjacent the opening of the tube, and wherein the end surface of the epoxy and the end plug define a gap therebetween configured to insulate the sensor electronics.  
     
     
         7 . An implantable sensor unit comprising: 
 a) a tube defining a chamber and an opening communicating with the chamber;    b) sensor electronics disposed in the chamber;    c) epoxy disposed in the chamber and surrounding the sensor electronics, the epoxy having an end surface adjacent the opening of the tube; and    d) a retaining cap including at least one projection extending outwardly from the tube;    e) wherein the retaining cap is secured to the tube by the epoxy.    
     
     
         8 . The sensor unit of  claim 7  configured such that the at least one projection will expand outwardly from the tube when exposed to at least one of heat and moisture.  
     
     
         9 . The sensor unit of  claim 7  including a bio-compatible anti-migration coating disposed on an outer surface of the tube.  
     
     
         10 . The sensor unit of  claim 7  including an anti-migration mesh layer disposed on an outer surface of the tube.  
     
     
         11 . An implantable sensor unit comprising: 
 a) a sensor housing defining an elongated chamber;    b) sensor electronics disposed in the chamber; and    c) a retention device mounted on the sensor housing, the retention device including a band surrounding a portion of the sensor housing and at least one projection secured to and extending from the band.    
     
     
         12 . The sensor unit of  claim 11  wherein the band is formed of an elastomeric material.  
     
     
         13 . An implantable sensor unit comprising: 
 a) a sensor housing having an outer surface and defining a chamber;    b) sensor electronics disposed in the chamber, wherein the sensor electronics are adapted to wirelessly transmit data; and    c) a bio-compatible anti-migration coating disposed on the outer surface, wherein the anti-migration coating is a Parylene C coating.    
     
     
         14 . The sensor unit of  claim 13  wherein the sensor housing is formed of glass.  
     
     
         15 . The sensor unit of  claim 13  wherein the Parylene C coating has a thickness of between about 10,000 and 60,000 Angstroms.  
     
     
         16 . An implantable sensor unit comprising: 
 a) a sensor housing having an outer surface and defining a chamber; and    b) a bio-compatible anti-migration mesh layer disposed on the outer surface.    
     
     
         17 . The sensor unit of  claim 16  wherein the sensor housing is formed of glass.  
     
     
         18 . The sensor unit of  claim 16  wherein the mesh layer is formed of polypropylene.  
     
     
         19 . A method for forming a sensor unit, the method comprising the steps of: 
 a) inserting an uncured epoxy into a tube in a fluid state;    b) inserting sensor electronics into the uncured epoxy in the tube;    c) evacuating air bubbles from the epoxy and the sensor electronics in the tube; and then    d) curing the epoxy.    
     
     
         20 . The method of  claim 19  including the step of mounting and sealing a closure member onto the tube.  
     
     
         21 . The method of  claim 19  including the step of laser sealing an open end of the tube.  
     
     
         22 . A method for forming a sensor unit, the method comprising the steps of: 
 a) inserting an uncured epoxy in a fluid state into a tube through an opening in the tube;    b) inserting sensor electronics into the uncured epoxy;    c) curing the epoxy such that the epoxy stabilizes the sensor electronics; and    d) sealing the opening in the tube to form a hermetically sealed tube.    
     
     
         23 . The method of  claim 22  wherein the step of sealing the opening in the tube includes at least one of flame sealing and laser sealing the tube.  
     
     
         24 . The method of  claim 22  including the step of applying a bio-compatible anti-migration coating to an outer surface of the tube using a plasma polymerization thin film deposition technique.  
     
     
         25 . The method of  claim 22  including the step of applying a bio-compatible anti-migration coating to an outer surface of the tube using vapor deposition polymerization.  
     
     
         26 . The method of  claim 22  including applying an anti-migration mesh layer to an outer surface of the tube.  
     
     
         27 . A method for forming a sensor unit, the method comprising the steps of: 
 a) providing a sensor housing having an outer surface and defining a chamber;    b) providing sensor electronics in the chamber, wherein the sensor electronics are adapted to wirelessly transmit data; and    c) applying a bio-compatible anti-migration coating to the outer surface of the sensor housing using a plasma polymerization thin film deposition technique.    
     
     
         28 . The method of  claim 27  wherein the sensor housing is formed of glass.  
     
     
         29 . The method of  claim 27  wherein the anti-migration coating has a thickness of between about 4,000 and 60,000 Angstroms.  
     
     
         30 . The method of  claim 27  wherein the anti-migration coating is a polypropylene thin film.  
     
     
         31 . A method for forming a sensor unit, the method comprising the step of: 
 a) providing a sensor housing having an outer surface and defining a chamber;    b) providing sensor electronics in the chamber, wherein the sensor electronics are adapted to wirelessly transmit data; and    c) applying a bio-compatible anti-migration coating to the outer surface of the sensor housing, wherein the anti-migration coating is a Parylene C coating.    
     
     
         32 . The method of  claim 31  wherein the Parylene C coating has a thickness of between about 10,000 and 60,000 Angstroms.  
     
     
         33 . The method of  claim 31  including using vapor deposition polymerization to apply the anti-migration coating to the outer surface of the sensor housing.  
     
     
         34 . A method for forming a sensor unit, the method comprising the step of: 
 applying a bio-compatible anti-migration mesh layer to an outer surface of a sensor housing.    
     
     
         35 . An implantable sensor unit comprising: 
 a) a sensor housing having an outer surface; and    b) a bio-compatible anti-migration layer surrounding at least a portion of the outer surface of the sensor housing;    c) wherein the anti-migration layer is formed of a textile material.    
     
     
         36 . The sensor unit of  claim 35  wherein the sensor housing is formed of glass.  
     
     
         37 . The sensor unit of  claim 35  wherein the anti-migration layer is a flexible sleeve.  
     
     
         38 . The sensor unit of  claim 37  wherein the sleeve substantially fully envelops the sensor housing.  
     
     
         39 . The sensor unit of  claim 35  wherein the anti-migration layer comprises a multi-filament textile material.  
     
     
         40 . The sensor unit of  claim 39  wherein the anti-migration layer comprises a multi-filament suture material.  
     
     
         41 . The sensor unit of  claim 39  wherein the anti-migration layer comprises a braided material.  
     
     
         42 . The sensor unit of  claim 39  wherein the anti-migration layer comprises polyester filaments.  
     
     
         43 . The sensor unit of  claim 35  wherein the textile material is substantially non-absorbable and non-degradable in a human body.  
     
     
         44 . The sensor unit of  claim 35  wherein the textile material is absorbable in a human body.  
     
     
         45 . The sensor unit of  claim 35  wherein the anti-migration layer is substantially free of pores having a size greater than 15 microns.  
     
     
         46 . The sensor unit of  claim 35  wherein the anti-migration layer is a mesh having a pore size of at least 25 microns.  
     
     
         47 . The sensor unit of  claim 35  wherein the anti-migration layer includes a holding tab extending beyond an end of the housing.  
     
     
         48 . A method for forming an implantable sensor unit, the method comprising: 
 a) providing a sensor housing; and    b) placing a bio-compatible anti-migration layer over the outer surface of the sensor housing, the anti-migration layer being formed of a textile material.    
     
     
         49 . The method of  claim 48  including forming the anti-migration layer from a multi-filament textile material.  
     
     
         50 . The method of  claim 48  including forming the anti-migration layer from a multi-filament suture material.  
     
     
         51 . The method of  claim 48  including forming the anti-migration layer as a sleeve.  
     
     
         52 . The method of  claim 51  including closing an open end of the sleeve to secure the sleeve about the sensor housing.  
     
     
         53 . The method of  claim 51  including forming the sleeve directly on the outer surface of the sensor housing using a plurality of filaments.  
     
     
         54 . The method of  claim 53  wherein the step of forming the sleeve directly on the outer surface of the housing includes braiding the plurality of filaments about the sensor housing.  
     
     
         55 . The method of  claim 51  including: 
 a) forming the sleeve on a mandrel using a plurality of filaments; and thereafter  
 b) mounting the sleeve on the sensor housing.  
 
     
     
         56 . The method of  claim 55  wherein the step of mounting the sleeve on the sensor housing is executed directly after forming the sleeve on a mandrel.  
     
     
         57 . The method of  claim 55  wherein the step of forming the sleeve on the mandrel includes braiding the plurality of filaments about the mandrel.  
     
     
         58 . The method of  claim 48  including forming a holding tab on the anti-migration layer and mounting the anti-migration layer on the sensor housing such that the holding tab extends beyond an end of the sensor housing.  
     
     
         59 . The method of  claim 58  including: 
 a) forming the anti-migration layer as a sleeve; and  
 b) closing an end of the sleeve to form the holding tab.  
 
     
     
         60 . An implantable sensor unit comprising: 
 a) a sensor housing having an end and defining a chamber;    b) sensor electronics disposed in the chamber; and    c) a holding tab extending from the end of the housing, the holding tab being adapted to facilitate handling of the housing.    
     
     
         61 . The sensor unit of  claim 60  wherein the sensor housing is formed of glass.  
     
     
         62 . The sensor unit of  claim 60  wherein the holding tab is flexible.  
     
     
         63 . The sensor unit of  claim 62  wherein the holding tab is formed of a textile material.  
     
     
         64 . The sensor unit of  claim 60  wherein the holding tab has a length of between about 2 and 10 mm.  
     
     
         65 . The sensor unit of  claim 60  including a sleeve surrounding at least a portion of the sensor housing, wherein the holding tab is integral with the sleeve.  
     
     
         66 . The sensor unit of  claim 65  wherein the sleeve and the holding tab are formed of a textile material.  
     
     
         67 . A method for implanting an implantable sensor unit in a body, the sensor unit including a sensor housing, the method comprising: 
 handling the sensor housing in the body using a holding tab extending from an end of the housing.    
     
     
         68 . The method of  claim 67  wherein the step of handling the sensor housing includes moving the sensor unit within the body while performing a surgical procedure.  
     
     
         69 . The method of  claim 68  wherein the step of handling the sensor housing includes moving the sensor unit within the body using an insertion tool.  
     
     
         70 . The method of  claim 68  wherein the step of handling the sensor housing includes moving the sensor unit within the body during an open surgical procedure.  
     
     
         71 . The method of  claim 67  including securing the holding tab to tissue of the body to thereby secure the implantable sensor unit.  
     
     
         72 . A method for using an implantable sensor unit in a body, the method comprising: 
 a) implanting the sensor unit in the body;    b) conducting an imaging procedure on the body such that the sensor unit in the body serves as a fiducial marker;    c) detecting a parameter using the sensor unit in the body; and    d) transmitting data associated with the detected parameter from the sensor unit to a remote receiver unit.    
     
     
         73 . The method of  claim 72  wherein the imaging procedure includes a radiographic imaging procedure and at least a portion of the sensor unit is radiopaque.  
     
     
         74 . An implantable sensor unit comprising: 
 a) a sensor housing having an outer surface; and    b) a bio-compatible anti-migration layer surrounding at least a portion of the outer surface of the sensor housing;    c) wherein the anti-migration layer is formed of a heat shrinkable thermoplastic material.    
     
     
         75 . A method for forming a sensor unit, the method comprising the step of: 
 a) providing a sensor housing having an outer surface and defining a chamber;    b) providing sensor electronics in the chamber, wherein the sensor electronics are adapted to wirelessly transmit data;    c) placing a bio-compatible anti-migration layer about the sensor housing, wherein the anti-migration layer is formed of a heat shrinkable thermoplastic material; and    d) heating the anti-migration layer to shrink the anti-migration layer about the sensor housing.