Magnetocaloric pump for microfluidic applications

Abstract

A microfluidic magnetocaloric pump. The magnetic and thermal properties of a ferrofluid such as MnZnFe 2 O 4 nanoparticles in an oil- or water-based medium are allowed to interact with a magnetic field that is partially coincident with a thermal gradient. As the ferrofluid heats, it loses its attraction to the magnetic field and is displaced by cooler fluid. The micropump produces fluid propulsion with no moving mechanical parts while requiring only 35 mW power and operation at a temperature of only 40-80° C.

1 . A structure for use with a ferrofluid comprising: 
 a fluid channel for containing a ferrofluid;    a heat source near said fluid channel; and    a magnetic source near said fluid channel such that the magnetic field of said magnetic source is partially coincident with the thermal field of said heat source.    
   
   
       2 . The structure of  claim 1  wherein said ferrofluid is MnZnFe 2 O 4  nanoparticles in a liquid medium.  
   
   
       3 . The structure of  claim 2  wherein said liquid medium is oil.  
   
   
       4 . The structure of  claim 2  wherein said liquid medium is water.  
   
   
       5 . The structure of  claim 1  wherein said heat source is a joule heater for generating flow of the ferrofluid within the fluid channel due to the interaction of said heat source and said magnetic source with the ferrofluid in said fluid channel.  
   
   
       6 . The structure of  claim 1  wherein said heat source is cooled by flow of the ferrofluid, and wherein said ferrofluid flow is caused by the interaction of said heat source, said magnetic source with the ferrofluid.  
   
   
       7 . The structure of  claim 6  wherein said heat source is an electric generator.  
   
   
       8 . The structure of  claim 6  wherein said heat source is an electric motor.  
   
   
       9 . The structure of  claim 8  wherein said electric motor is a brushless dc motor.  
   
   
       10 . A self-regulating method for cooling a heat source comprising the steps of: 
 locating a fluid channel containing a ferrofluid near a heat source; and    locating a magnetic source near said fluid channel such that the magnetic field of said magnetic source is partially coincident with the thermal field of said heat source, and cooling of the heat source is due to flow of the ferrofluid caused by the interaction of said heat source and said magnetic source with the ferrofluid.