Microdevice arrays formed by magnetic assembly

Abstract

Microdevices containing a predetermined preferential axis of magnetization are disposed in an array having discreet regions. Under influence of a magnetic field, the microdevices can have at least twelve discrete orientations, and can advantageously be flipped upside down in place. Microdevices can be coded in a manner that supports a coding space of at least 10 2 , 10 3 , 10 6 or even 10 10 or more choices, and can include one or more chemically reactive sites. The regions can be defined by long and short bars, in which microdevices span gaps between the longer bars, and the shorter bars measure less than 60% of such gaps. Preferred embodiments are also provided to produce microfabricated microdevices for magnetic assembly-based arraying.

What is claimed is: 
     
         1 . A method of forming an array of microdevices, comprising:
 providing an arraying chip comprising a substrate having magnetizable magnetic elements, the elements each having an element predetermined preferential axis of magnetization and forming an array of discrete regions that can each exert magnetic forces in response to an external magnetic field,   wherein an induced magnetization in its absolute magnitude along the element preferential axis of magnetization of magnetization of each element is at least 20% more than an induced magnetization of said element along at least one other axis;   providing the external magnetic field from a magnetic field generator to direct array formation; and   arraying manufactured microdevices, the microdevices each having a microdevice predetermined preferential axis of magnetization, wherein an induced magnetization in its absolute magnitude along the microdevice predetermined preferential axis of the magnetization of each microdevice is at least 20% more than an induced magnetization of said microdevice along at least one other axis.   
     
     
         2 . The method of  claim 1 , wherein the orientation of the microdevices in the array can be directed to at least two discrete orientations of the microdevices. 
     
     
         3 . The method of  claim 1 , wherein the orientation of the microdevices in the array can be directed to at least four discrete orientations of the microdevices. 
     
     
         4 . The method of  claim 1 , wherein the orientation of the microdevices in the array can be directed to at least eight discrete orientations of the microdevices. 
     
     
         5 . The method of  claim 1 , wherein the orientation of the microdevices in the array can be directed to at least twelve discrete orientations of the microdevices. 
     
     
         6 . The method of  claim 1 , wherein each of the microdevices have a longest linear dimension of 500 microns. 
     
     
         7 . The method of  claim 1 , wherein the arrayed microdevices completely overlap a magnetizable magnetic element of the array. 
     
     
         8 . The method of  claim 1 , wherein the arrayed microdevices comprise a patterned magnetic bar. 
     
     
         9 . A method of altering orientation of microdevices having a largest linear dimension of less than 500 flM, comprising:
 positioning the microdevices in an array on an arraying chip comprising a substrate having an array of embedded magnetizable magnetic elements, the magnetizable magnetic elements each having an element predetermined preferential axis of magnetization that exerts magnetic forces in response to an external magnetic field, where the microdevices are disposed according to a first orientation relative to the magnetic elements,   wherein an induced magnetization in its absolute magnitude along the element predetermined preferential axis of the magnetization of each element is at least 20% more than an induced magnetization of said element along at least one other axis; and   applying at least first and second external magnetic fields in a sequence such that selected ones of the arrayed micro devices are re-oriented by at least 90°.   
     
     
         10 . The method of  claim 9 , wherein the array of microdevices in the first orientation is substantially disposed in a plane parallel to the arraying chip, and the selected ones of the microdevices are re-oriented perpendicularly to the plane. 
     
     
         11 . The method of  claim 9 , wherein the selected ones of the microdevices are flipped upside down. 
     
     
         12 . The method of  claim 9 , wherein the selected ones of the microdevices are flipped upside down without changing their locations in the array. 
     
     
         13 . The method of  claim 9 , wherein individual ones of the micro devices include codes that utilize a magnetic coding space that supports at least 10 3  choices. 
     
     
         14 . The method of  claim 9 , wherein each of individual ones of the microdevices include a chemically reactive site. 
     
     
         15 . The method of  claim 9 , wherein the microdevices comprise at least 100 microdevices that have mutually distinct polymers and mutually distinct codes. 
     
     
         16 . An article of manufacture, comprising:
 a set of microdevices each having a longest linear dimension of no more than 1 mm, a thickness of less than 50 μM; and   a bar of magnetic material disposed off-center in said microdevice,
 wherein each bar is sized and dimensioned to be complementary to dimensions of magnetic bars within an arraying chip, 
 wherein each of the microdevices has a predetermined preferential axis of magnetization, and 
 wherein an induced magnetization in its absolute magnitude along the preferential axis of the magnetization of said microdevice is at least 20% more than an induced magnetization of said microdevice along at least one other axis. 
   
     
     
         22 . The article of claim  21 , wherein members of the set have a longest linear dimension of no more than 500 microns. 
     
     
         23 . The article of claim  21 , wherein members of the set utilize a magnetic coding space that supports at least 10 3  choices. 
     
     
         24 . The article of claim  21 , wherein members of the set include mutually distinct polymers and mutually distinct codes. 
     
     
         25 . The article of claim  21 , wherein members of the set include a chemically reactive site.