Feedback control in microfluidic systems

Abstract

Systems and methods for controlling fluids in microfluidic systems are generally described. In some embodiments, control of fluids involves the use of feedback from one or more processes or events taking place in the microfluidic system. For instance, a detector may detect one or more fluids at a measurement zone of a microfluidic system and one or more signals, or a pattern of signals, may be generated corresponding to the fluid(s). In some cases, the signal or pattern of signals may correspond to an intensity, a duration, a position in time relative to a second position in time or relative to another process, and/or an average time period between events. Using this data, a control system may determine whether to modulate subsequent fluid flow in the microfluidic system. In some embodiments, these and other methods can be used to conduct quality control to determine abnormalities in operation of the microfluidic system.

What is claimed is: 
     
         1 . A method of conducting quality control to determine abnormalities in operation of a microfluidic system, comprising:
 detecting a first fluid at a first measurement zone of the microfluidic system and forming a first signal corresponding to the first fluid, wherein the first fluid is a fluid sample;   transmitting the first signal to a control system;   comparing the first signal to a reference signal, thereby determining the presence of abnormalities in operation of the microfluidic system; and   determining whether to stop an analysis being conducted in the microfluidic system and/or alerting a user of an abnormality in an analysis being conducted in the microfluidic system based at least in part on results of the comparing step.   
     
     
         2 . A method as in  claim 1 , comprising detecting a second fluid at the first measurement zone of the microfluidic system and forming a second signal corresponding to the second fluid. 
     
     
         3 . A method as in  claim 1 , comprising continuously or periodically detecting the passing of any fluids across the first measurement zone. 
     
     
         4 . A method as in  claim 1 , comprising determining whether to stop an analysis being conducted in the microfluidic system. 
     
     
         5 . A method as in  claim 1 , further comprising transmitting an electrical signal from the control system to a component of the microfluidic system that can modulate fluid flow as a result of the transmitting step. 
     
     
         6 . A method as in  claim 5 , wherein the component of the microfluidic system is a pump or a vacuum. 
     
     
         7 . A method as in  claim 5 , wherein the component of the microfluidic system is a valve. 
     
     
         8 . A method as in  claim 2 , wherein the first signal and second signal form a first pattern of signals, the method comprising transmitting the first pattern of signals to a control system, the first pattern of signals comprising at least two of:
 a) an intensity of the first signal;   b) a duration of the first signal;   c) a position of the first signal in time relative to a second position in time; and   d) an average time period between the first and second signals; and   further comprising comparing the first pattern of signals to a control pattern of signals or values pre-programmed into the control system.   
     
     
         9 . A method as in  claim 8 , wherein the intensity of the first signal comprises an average or maximum intensity. 
     
     
         10 . A method as in  claim 8 , wherein the first pattern of signals comprises an intensity of the first signal and a duration of the first signal. 
     
     
         11 . A method as in  claim 8 , wherein the first pattern of signals comprises an intensity of the first signal and a position of the first signal in time relative to a time of an initiation step. 
     
     
         12 . A method as in  claim 2 , further comprising detecting each any subsequent fluid that passes across the first measurement zone during the analysis, forming a signal for each any subsequent fluid to produce a fingerprint of the analysis, and determining whether the analysis is run properly based on the fingerprint. 
     
     
         13 . A method as in  claim 1 , wherein the first fluid is serum or plasma. 
     
     
         14 . A method as in  claim 2 , wherein the first and second fluids are immiscible with one another. 
     
     
         15 . A method as in  claim 2 , wherein the first fluid is a liquid and the second fluid is a gas. 
     
     
         16 . A method as in  claim 2 , wherein the first and second fluids are miscible with one another. 
     
     
         17 . A method as in  claim 2 , wherein the first and second fluids are separated by a third, immiscible fluid. 
     
     
         18 . A method as in  claim 1 , wherein the first fluid comprises whole blood. 
     
     
         19 . A method as in  claim 2 , wherein the second fluid is air. 
     
     
         20 . A method as in  claim 1 , comprising alerting a user of an abnormality in an analysis being conducted in the microfluidic system.