Transcutaneous medical device with variable stiffness

Abstract

The present invention relates generally to variable stiffness transcutaneous medical devices including a distal portion designed to be more flexible than a proximal portion. The variable stiffness can be provided by a variable pitch in one or more wires of the device, a variable cross-section in one or more wires of the device, and/or a variable hardening and/or softening in one or more wires of the device.

1 - 20 . (canceled) 
     
     
         21 . A transcutaneous analyte sensor assembly, the assembly comprising:
 a sensor, wherein the sensor includes
 a distal portion, adapted to be inserted through a skin of a host such that in use the distal portion is in vivo, 
 an intermediate portion, and 
 a proximal portion adapted to remain substantially external to the host such that in use the proximal portion is ex vivo when the distal portion is inserted in the host; 
   wherein a stiffness of the sensor is variable along a length of the sensor and wherein the proximal, ex vivo, portion is stiffer than the distal, in vivo, portion; and   a housing configured for mounting on a skin of a host.   
     
     
         22 . The sensor assembly of  claim 21 , further comprising an electronics unit configured to operably connect to the sensor. 
     
     
         23 . The sensor assembly of  claim 22 , wherein the housing comprises electrical contacts configured to operably connect the sensor to the electronics unit. 
     
     
         24 . The sensor assembly of  claim 21 , wherein the sensor is configured to absorb a relative movement between the proximal, ex vivo, portion and the distal, in vivo, portion. 
     
     
         25 . The sensor assembly of  claim 21 , wherein the sensor comprises at least one wire in a helical configuration, and wherein a difference in stiffness of the distal portion and the proximal portion is provided by varying a pitch of the helical configuration. 
     
     
         26 . The sensor assembly of  claim 25 , wherein the sensor comprises at least one wire in a helical configuration, and wherein a difference in flexibility of the distal portion and the proximal portion is provided by varying a cross-section of the wire. 
     
     
         27 . The sensor assembly of  claim 21 , wherein the sensor comprises at least one wire, and wherein a difference in flexibility of the distal portion and the proximal portion is provided by varying a hardness of the wire. 
     
     
         28 . The sensor assembly of  claim 27 , wherein a variation in stiffness of the elongated flexible portion of the sensor is produced by subjecting the wire to an annealing process. 
     
     
         29 . The sensor assembly of  claim 21 , wherein the intermediate portion of the sensor is more flexible than at least one of the distal portion and the proximal portion. 
     
     
         30 . The sensor assembly of  claim 29 , wherein the distal portion of the sensor comprises a distal tip on an end of the sensor that is stiffer than a substantial portion of the sensor. 
     
     
         31 . The sensor assembly of  claim 21 , wherein the ex vivo portion of the sensor has a preselected stiffness to maintain a stable connection between the sensor and the electrical contacts. 
     
     
         32 . The sensor assembly of  claim 21 , wherein the in vivo portion of the sensor has a preselected flexibility to minimize mechanical stresses caused by motion of the host.