Transducer for microfluid handling system

Abstract

The present invention relates to integrated micro-cantilevers, micro-bridges or micro-membranes in micro-liquid handling systems. Such micro-liquid handling systems provide novel detection mechanisms for monitoring the physical, chemical and biological properties of fluids in such systems. The present invention further relates to micro-cantilever, micro-bridge or micro-membrane type sensors having integrated readout. Such constructions allow laminated flows of different liquids to flow in a channel without mixing, which opens up for new type of experiments and which reduces noise related to the liquid movement. The present invention even further relates to sensors having adjacent or very closely spaced micro-cantilevers, micro-bridges or micro-membranes which can be exposed to different chemical environments at the same time.

1 - 71 . (canceled)  
     
     
         72 . A method for detecting the presence of a first substance in a fluid, said method comprising providing a sensor comprising a first flexible member and a handling means for the fluid, said handling means comprising an interaction chamber of micrometer dimensions, an inlet and an outlet, said first flexible member having a surface holding a second substance, said surface holding the second substance is at least partly positioned inside the interaction chamber so that at least a part of the second substance is exposed to the fluid in said interaction chamber, said first flexible member comprises a piezoresistive element for detecting a mechanical parameter associated with the first flexible member, said mechanical parameter being related to the presence of the substance in the fluid, said method comprises introducing the liquid into the interaction chamber and then temporarily stopping the liquid flow while the measurement is being performed.  
     
     
         73 . A method according to  claim 72 , wherein the piezoresistive element forms part of a balanced bridge.  
     
     
         74 . A method according to  claim 73 , wherein the balanced bridge is a Wheatstone bridge.  
     
     
         75 . A method according to  claim 72 , wherein the mechanical parameter is a deflection parameter, in the form of a bending or a change in bending or in the form of a change of resonant frequency.  
     
     
         76 . A method according to  claim 72 , wherein said interaction chamber has a width and depth of 100-500 μm.  
     
     
         77 . A method according to  claim 72 , wherein the mechanical parameter is a change of surface stress.  
     
     
         78 . A method according to  claim 72 , wherein the change of stress is measured as a change of resistance.  
     
     
         79 . A method according to  claim 72 , wherein the mechanical parameter is a dynamic parameter.  
     
     
         80 . A method according to  claim 79 , wherein the first flexible member being driven at or near its mechanical resonance frequency, so that upon detection of the first substance in the fluid the resonance frequency will change due to a change of mass of the flexible member.  
     
     
         81 . A sensor for detecting the presence of a first substance in a fluid said sensor comprising a first flexible member and a handling means for the fluid, said handling means comprising an interaction chamber of micrometer dimensions, an inlet and an outlet, said handling means further being arranged for temporarily stopping a liquid flow in said interaction chamber while a measurement is being performed, said first flexible member having a surface holding a second substance, said surface holding the second substance is at least partly positioned inside the interaction chamber so that at least a part of the second substance is exposed to a fluid in said interaction chamber, said first flexible member comprises a piezoresistive element for detecting a mechanical parameter associated with the first flexible member, said mechanical parameter being related to the presence of the substance in the fluid.  
     
     
         82 . A sensor according to  claim 81 , wherein the piezoresistive element forms part of a balanced bridge.  
     
     
         83 . A sensor according to  claim 82 , wherein the balanced bridge is a Wheatstone bridge.  
     
     
         84 . A sensor according to  claim 81 , wherein said interaction chamber has a width and depth of 100-500 μm.  
     
     
         85 . A sensor according to  claim 81 , wherein the mechanical parameter is a dynamic parameter said sensor comprises an actuator for moving the flexible member relative to the interaction chamber.  
     
     
         86 . A sensor according to  claim 85 , wherein the actuator comprises a piezoelectric element.  
     
     
         87 . A sensor according to  claim 85 , wherein the actuator comprises means for providing an electrostatic induced movement of the flexible member.  
     
     
         88 . A sensor according to  claim 85 , wherein the actuator comprises means for providing a magnetic induced movement of the flexible member.  
     
     
         89 . A sensor according to  claim 85 , wherein the actuator comprises means for providing a thermal induced movement of the flexible member.