Method of setting and actuating a multi-stable micro valve and adjustable micro valve

Abstract

A micro valve and a method for setting or actuating a micro valve for use in fluidic applications includes cooling an array of actuating members made of Shape Memory Alloy (SMA) material. The SMA material is cooled to a temperature equal to or below the temperature at which a transformation from austenitic to martensitic state occurs so that the entire array of SMA actuating members is either fully or partially in the martensitic state. At least one of the actuating member is selected to correspond to a pre-determined opening pressure or flow resistance. Each of the actuating members are heated individually, except the previously selected one, to a temperature equal to or above the temperature at which a transformation from the martensitic state to the austensitic state occurs.

1 . A method of setting and actuating an adjustable micro valve that comprises the steps of: 
 cooling an array of actuating members made of SMA material, to a temperature equal or below the temperature at which a transformation from austenitic to martensitic state occurs so that the entire array of SMA actuating members is either fully or partially in the martensitic state;    selecting at least one of the actuating members corresponding to a pre-determined opening pressure or resistance to flow; and    heating individually each of the actuating members except the previously selected member to a temperature equal to or above the temperature at which a transformation from the martensitic state to the austensitic state occurs.    
   
   
       2 . A method according to  claim 1  wherein the actuating members are made of a SMA material having two stable states at body temperature and an hysteresis comprised between 10 and 40 degrees centigrade.  
   
   
       3 . A method of setting and actuating an adjustable micro valve comprising the steps of: 
 heating an array of actuating members made of SMA material, to a temperature equal or above the temperature at which a transformation from martensitic to austenitic state occurs so that the entire array of SMA actuating members is either fully or partially in the austenitic state;    selecting at least one of the actuating members corresponding to a pre-determined opening pressure or resistance to flow; and    cooling individually the selected actuating members to a temperature equal or below to the temperature at which a transformation from the austenitic state to the martensitic state occurs.    
   
   
       4 . A method according to  claim 3  wherein the actuating members are made of a SMA material having two stable states at body temperature and an hysteresis comprised between 10 and 40 degrees centigrade.  
   
   
       5 . An adjustable micro valve comprising: 
 a base element having a base plate face and at least one passage for the flow of fluid;    at least one array of actuating members made of a SMA material arranged on the base plate face;    means for cooling at least one of the actuating members; and    means for heating at least one of the actuating members.    
   
   
       6 . An adjustable micro valve according to  claim 5 , further comprising an elastic element securing a ball in the seat of an opening and in that the actuating members are conformed so that one of their free ends interacts with a portion of the elastic element allowing alteration of its elasticity.  
   
   
       7 . An adjustable micro valve according to  claim 5 , wherein the actuating members are conformed so that one of their free ends closes a corresponding orifice in the base element.  
   
   
       8 . An adjustable micro valve according to  claim 5 , wherein the cooling means include at least one Peltier cell integrated in the base element in the vicinity of the at least one array of SMA actuating members.  
   
   
       9 . An adjustable micro valve according to  claim 6 , wherein the cooling means include at least one Peltier cell integrated in the base element in the vicinity of the at least one array of SMA actuating members.  
   
   
       10 . An adjustable micro valve according to  claim 7 , wherein the cooling means include at least one Peltier cell integrated in the base element in the vicinity of the at least one array of SMA actuating members.  
   
   
       11 . An adjustable micro valve according to one of the  claim 5 , wherein the actuating members are made of TiNi.  
   
   
       12 . An adjustable micro valve according to one of the  claim 6 , wherein the actuating members are made of TiNi.  
   
   
       13 . An adjustable micro valve according to one of the  claim 7 , wherein the actuating members are made of TiNi.  
   
   
       14 . An adjustable micro valve according to one of the  claim 8  wherein the actuating members are made of TiNi.  
   
   
       15 . An implantable micro valve having an adjustable opening pressure comprising: 
 an upper cover having a fluid outlet;    a bottom cover connected to the upper cover thereby defining an interior chamber, said bottom cover having a fluid inlet;    a micro valve disposed within the interior chamber having a base plate face; and    electrical components and an antenna disposed within the interior chamber for energizing and controlling the actuation of the micro valve by telemetry.    
   
   
       16 . An implantable pump comprising: 
 an upper cover having a fluid outlet;    a bottom cover connected to the upper cover thereby defining an interior chamber;    a pressurised reservoir disposed within the interior chamber;    a micro valve assembly disposed within the interior chamber, the micro valve having a base element having: 
 a base plate face and at least one passage for the flow of fluid;  
 at least one array of actuating members made of a SMA material arranged on the base plate face;  
 means for cooling at least one array of actuating members; and  
 means for heating at least one array of actuating members; and  
   electrical components and an antenna disposed within the interior chamber for energizing and controlling the actuation of the pump by telemetry.