Additive manufacture of complex implantable living devices

Abstract

A cell-scaffold device includes at least one channel network including an inlet, a plurality of channels include a parent channel having an end portion communicating with the inlet and another end portion communicating with a first bifurcation, forming two child channels. Each child channel has an end portion communicating with a respective end portion of the first bifurcation and another end portion communicating with a second bifurcation, forming two grand-child channels from each child channel. Each grand-child channel has an end portion communicating with a respective end portion of the second bifurcation and another end portion. The other end portion of the grand-child channel either forms an outlet or a third child channel in communication with the grand-child channel. Each forming of grand-child channels defines a generation of the fractal structure. The devices are of use as scaffolds for seeding, growing, and maintaining cells implanted in and/or on the device.

What is claimed is: 
     
         1 . A cell-scaffold device having a fractal structure utilized for growing tissue, wherein the device comprises at least one channel network comprising:
 an inlet;   a plurality of channels comprising:
 a parent channel having a first end portion in communication with the inlet and a second end portion in communication with a first bifurcation, thereby forming two child channels, 
 each child channel having a first end portion in communication with a respective end portion of the first bifurcation and a second end portion in communication with a second bifurcation, thereby forming two grand-child channels from each child channel, and 
 each grand-child channel having a first end portion in communication with a respective end portion of the second bifurcation and a second end portion, wherein the second end portion of the grand-child channel either forms an outlet or a third child channel in communication with the grand-child channel, 
 wherein each forming of grand-child channels defines a generation of the fractal structure. 
   
     
     
         2 . The scaffold device of  claim 1 , wherein the device is formed as a positive mold such that walls of the channels are being formed. 
     
     
         3 . The scaffold device of  claim 1 , wherein the channel network is formed from a non-resorbable material, a biodegradable material, a non-resorbable material, or a combination thereof. 
     
     
         4 . The scaffold device of  claim 1 , wherein:
 a diameter of a smallest channel is predetermined; and   each preceding channel after the smallest channel has a diameter increased by a first predetermined factor relative to a diameter of an immediately subsequent channel.   
     
     
         5 . The scaffold device of  claim 1 , wherein:
 a diameter of the inlet is predetermined; and   each subsequent channel after the inlet has a diameter reduced by a first predetermined factor relative to a diameter of an immediately preceding channel.   
     
     
         6 . The scaffold device of  claim 5 , wherein the first predetermined factor is defined by Murray's Law, D o   3 =Σ i=1  D i , wherein:
 D o  is a diameter of the parent channel; 
 n is a number of child channels; and 
 D i  is a diameter of an i th  child channel. 
 
     
     
         7 . The scaffold device of  claim 5 , wherein the first predetermined factor is a constant less than or equal to 1. 
     
     
         8 . The scaffold device of  claim 1 , wherein:
 a length of the parent channel is predetermined; and   a length of each subsequent channel is reduced by a second predetermined factor relative to a length of an immediately preceding channel.   
     
     
         9 . The scaffold device of  claim 8 , wherein the second predetermined factor is a constant less than or equal to 1. 
     
     
         10 . The scaffold device of  claim 1 , wherein a ratio of a diameter to a length of a channel is fixed along the length of the channel. 
     
     
         11 . The scaffold device of  claim 1 , wherein each channel and bifurcation exhibit laminar flow therein. 
     
     
         12 . The scaffold device of  claim 1 , wherein a connection between each channel and its corresponding bifurcation is a linear ramp, a smooth concave ramp, a smooth convex ramp, a step, a plurality of steps, or a reducer. 
     
     
         13 . The scaffold device of  claim 12 , wherein the connection is configured to have a surface of a channel in a channel network flush with a coplanar surface of each channel of the channel network. 
     
     
         14 . The scaffold device of  claim 1 , wherein each bifurcation branches at an angle in between 75° and 105° relative to an immediately preceding channel. 
     
     
         15 . The scaffold device of  claim 1 , wherein the inlet is a portion of a master inlet. 
     
     
         16 . The scaffold device of  claim 1 , wherein the second end portion grand-child channel is in communication with a third bifurcation, thereby forming two outlets. 
     
     
         17 . The scaffold device of  claim 1 , wherein the first channel network is recursively formed such that outlets of a first layer and outlets of a second layer combined to form a paired layer. 
     
     
         18 . The scaffold device of  claim 1 , wherein the at least one channel network comprises a first channel network and a second channel network which are linked through communicating outlets therebetween, thereby forming a first paired layer. 
     
     
         19 . The scaffold device of  claim 18 , wherein the first channel network is stacked onto the second channel network such that the outlets of the first channel network and the outlets of the second channel network are in communication, thereby allowing material to flow therebetween. 
     
     
         20 . The scaffold device of  claim 18 , wherein the first channel network is stacked onto the second channel network such that the outlets of the first channel network and the outlets of the second channel network are not in communication, thereby preventing material from flowing therebetween. 
     
     
         21 . The scaffold device of  claim 18 , wherein the communication is defined as either:
 a direct flow of material from the first channel network to the second channel network; or   an indirect flow of material from the first channel network to the second channel network by an exchange mechanism.   
     
     
         22 . The scaffold device of  claim 18 , wherein the communication is defined as either:
 a direct flow of material from the second channel network to the first channel network; or   an indirect flow of material from the second channel network to the first channel network by an exchange mechanism.   
     
     
         23 . The scaffold device of  claim 22 , wherein the exchange mechanism is mediated by a membrane or a plurality of pores. 
     
     
         24 . The scaffold device of  claim 18 , further comprising a third channel network and a fourth channel network which are linked through communicating outlets therebetween, thereby forming a second paired layer. 
     
     
         25 . The scaffold device of  claim 24 , wherein the first paired layer and the second paired layer communicate with each other through an exchange mechanism therebetween, thereby combining to form a stackable unit, or stack. 
     
     
         26 . The scaffold device of  claim 25 , wherein the first paired layers of each stack are in communication with each other by an exchange mechanism and the second paired layers of each stack are in communication with each other by the exchange mechanism, thereby forming a stacked first layer and a stacked second layer. 
     
     
         27 . The scaffold device of  claim 24 , wherein the inlets and the outlets of the first paired layers combine to form a first master inlet and a first master outlet, respectively, and the inlets and the outlets of the second paired layers combine to form a second master inlet and a second master outlet, respectively. 
     
     
         28 . The scaffold device of  claim 1 , wherein a thin film of collagen is disposed on the device. 
     
     
         29 . A cell-scaffold device having a fractal structure utilized for growing tissue, wherein the device comprises:
 a plurality of stackable units, or stacks, each stack comprising:
 a first channel network; and 
 a second channel network disposed below the first channel network, 
 wherein each channel network comprises:
 an inlet; 
 a plurality of channels comprising:
 a parent channel having a first end portion in communication with the inlet and a second end portion in communication with a first bifurcation, thereby forming two child channels, 
 each child channel having a first end portion in communication with a respective end portion of the first bifurcation and a second end portion in communication with a second bifurcation, thereby forming two grand-child channels from each child channel, and 
 each grand-child channel having a first end portion in communication with a respective end portion of the second bifurcation and a second end portion, wherein the second end portion of the grand-child channel either forms an outlet or a third child channel in communication with the grand-child channel, 
 wherein each bifurcation comprises a ramp or step at a front end portion thereof, such that each layer has a flush surface, 
 
 wherein each stack communicates with an adjacent stack by an exchange mechanism therebetween. 
 
   
     
     
         30 . A cell-scaffold device having a fractal structure utilized for growing tissue, wherein the device comprises:
 a plurality of stackable units, each unit comprising:
 a first channel network configured as inflow; 
 a second channel network and disposed below the first channel network; 
 a third channel network configured as an outflow and disposed below the second channel network; and 
 a fourth channel network disposed below the third network, 
 wherein each layer comprises:
 an inlet; 
 a plurality of channels comprising:
 a parent channel having a first end portion in communication with the inlet and a second end portion in communication with a first bifurcation, thereby forming two child channels, 
 each child channel having a first end portion in communication with a respective end portion of the first bifurcation and a second end portion in communication with a second bifurcation, thereby forming two grand-child channels from each child channel, and 
 each grand-child channel having a first end portion in communication with a respective end portion of the second bifurcation and a second end portion, wherein the second end portion of the grand-child channel either forms an outlet or a third child channel in communication with the grand-child channel, 
 wherein, 
  the outlets of the first layer communicate with the outlets of the third layer, 
  the outlets of the fourth layer and the second layer and are self-contained, and 
  each bifurcation comprises a ramp or step at a front end portion thereof, such that each layer has a flush surface, 
 
 
 wherein each stack communicates with an adjacent stack by an exchange mechanism therebetween.