Medical devices

Abstract

Medical devices and methods of making the devices are described. In some embodiments, the devices include multiple layers, and one or more layers can include a nanocomposite material.

1 . A co-extruded medical tube, comprising: 
 a first layer; and    a second layer disposed radially inwardly of the first layer,    wherein the first and second layers have different compositions, and one of the layers comprises a nanocomposite material and has a viscosity between 25% and 120% of a viscosity of the other layer as measured at a shear rate of 1 s −1  and a temperature of 220° C.    
     
     
         2 . The medical tube of  claim 1 , wherein the second layer is bonded directly to the first layer.  
     
     
         3 . The medical tube of  claim 1 , wherein the first layer is the outermost layer of the co-extruded tube.  
     
     
         4 . The medical tube of  claim 1 , further comprising a third layer having a different composition than the second layer, the third layer having a viscosity greater than a viscosity of the second layer as measured at a shear rate of 1 s −1  and a temperature of 220° C.  
     
     
         5 . The medical tube of  claim 4 , wherein the composition of the third layer is different that the composition of the first layer.  
     
     
         6 . The medical tube of  claim 5 , wherein the third layer is the innermost layer.  
     
     
         7 . The medical tube of  claim 1 , wherein the composition of the first layer is a nanocomposite.  
     
     
         8 . The medical tube of  claim 1 , wherein the composition of the second layer is a non-nanocomposite.  
     
     
         9 . The medical tube of  claim 1 , wherein the first and second layer has a thickness uniformity of 80% or greater around the circumference of the medical tube.  
     
     
         10 . A co-extruded medical tube comprising: 
 a first layer comprising a nanocomposite material having a first viscosity; and    a second layer comprising a second material and having a second viscosity,    wherein the first viscosity is from about 25% to about 120% of the second viscosity as measured at a shear rate less than about 1 s −1  and a temperature of about 60° C. to about 120° C. above a flow temperature of a highest flow temperature material that is co-extruded.    
     
     
         11 . The medical tube of  claim 10 , wherein the shear rate has a value of about 0.1 s −1 .  
     
     
         12 . The medical tube of  claim 10 , wherein the temperature is 220° C.  
     
     
         13 . The medical tube of  claim 1  further comprising a third co-extruded layer comprising a third material having a third viscosity that varies with shear rate, 
 wherein the second viscosity is from about 5% to about 35% of the third viscosity as measured at a shear rate less than about 1 s −1  and a temperature of about 60° C. to about 120° C. above a flow temperature of a highest flow temperature material that is co-extruded.    
     
     
         14 . The medical tube of  claim 10 , wherein the second material comprises Plexar® PX380, a modified polyolefin.  
     
     
         15 . The medical tube of  claim 13 , wherein the third material comprises Marlex®, a high density polyethylene.  
     
     
         16 . The medical tube of  claim 10 , wherein the first layer comprises at least about 30% of a cross-sectional area of the medical tube.  
     
     
         17 . The medical tube of  claim 10 , wherein the second layer comprises at least about 5% of a cross-sectional area of the medical tube.  
     
     
         18 . The medical tube of  claim 13 , wherein the third layer comprises at least about 10% of the medical device.  
     
     
         19 . The medical tube of  claim 10 , wherein the first layer and the second layer are coextensively co-extruded.  
     
     
         20 . The medical tube of  claim 10 , wherein the first layer and the second layer are intermittently co-extruded.  
     
     
         21 . A medical device comprising: 
 a tubular body comprising a plurality of co-extruded layers,    wherein a viscosity of a first layer is from about 25% to about 120% of a second viscosity of an adjacent layer as measured at a shear rate less than about 1 s −1  and a temperature of about 60° C. to about 120° C. above a flow temperature of a highest flow temperature material that is co-extruded.    
     
     
         22 . The medical device of  claim 21 , wherein the shear rate is below about 0.1 s −1 .  
     
     
         23 . The medical device of  claim 21 , wherein at least one of the plurality of co-extruded layers comprises a nanocomposite material.  
     
     
         24 . The medical device of  claim 21 , wherein the plurality of co-extruded layers comprises an outer nanocomposite layer, a middle layer, and an inner layer.  
     
     
         25 . The medical device of  claim 24 , wherein the middle layer comprises Plexar® PX380, a modified polyolefin.  
     
     
         26 . The medical device of  claim 24 , wherein the inner layer comprises Marlex®, a high density polyethylene.  
     
     
         27 . A method of manufacturing a device including a first layer and a second layer, the method comprising: 
 selecting a shear rate at or below about 1 s −1 ;    selecting a temperature;    selecting a material for the second layer, the material having a viscosity value at the shear rate and the temperature;    selecting a nanocomposite material for the first layer that has a viscosity within about 20% to about 125% of the viscosity value of the material for the second layer; and    co-extruding the first and second layers.    
     
     
         28 . The method of  claim 27 , wherein the device is a medical device.  
     
     
         29 . The method of  claim 27 , wherein the shear rate is below about 0.5 s −1 .  
     
     
         30 . The method of  claim 27 , wherein the shear rate is about0.1 s −1 .  
     
     
         31 . The method of  claim 27 , wherein the temperature is about 60° C. to about 120° C. above a flow temperature of a highest flow temperature material co-extruded.  
     
     
         32 . A tubular member comprising: 
 a first layer and a second layer co-extruded with the first layer, wherein one of the layers comprises a nanocomposite material, and one of the layers comprises a thickness that varies by less than about 20% from a mean value of thickness, the thickness being measured at four points per cross-sectional cut made at ten random, non-consecutive locations along a production length of the tubular member.    
     
     
         33 . The tubular member of  claim 32 , wherein the thickness varies by less than 15% from the mean value of thickness.  
     
     
         34 . The tubular member of  claim 32 , wherein the thickness varies by less than 10% from the mean value of thickness.  
     
     
         35 . The tubular member of  claim 32 , wherein the first layer has a first thickness that varies less than about 20% from a mean value of thickness for the first layer and the second layer has a second thickness that varies less than about 20% from a mean value of thickness for the second layer.  
     
     
         36 . The tubular member of  claim 33 , wherein the tubular member further comprises a third layer.  
     
     
         37 . A method of making a medical device, the method comprising: 
 forming a tubular member, the tubular member comprising a first layer and a second layer co-extruded with the first layer, wherein one of the layers comprises a nanocomposite material, and one of the layers comprises a thickness that varies by less than about 20% from a mean value of thickness, the thickness being measured at four points per cross-sectional cut made at ten random, non-consecutive locations along a production length of the tubular member; and    incorporating a portion of the tubular member as a component of the medical device.    
     
     
         38 . The method of  claim 37 , wherein the medical device is a catheter.  
     
     
         39 . The method of  claim 37 , wherein the medical device is a balloon-catheter.  
     
     
         40 . The method of  claim 37 , wherein the thickness varies by less than 15% from the mean value of thickness.  
     
     
         41 . The method of  claim 37 , wherein the thickness varies by less than 10% from the mean value of thickness.  
     
     
         42 . The method of  claim 37 , wherein the device is a stent delivery system, and the tubular member is a catheter or a sheath.