Microfluidic processing system and method of agricultural slurry

Abstract

An automated computer-controlled sampling system and related methods for collecting, processing, and analyzing agricultural samples for various chemical properties such as plant available nutrients. The sampling system allows multiple samples to be processed and analyzed for different analytes or chemical properties in a simultaneous concurrent or semi-concurrent manner. Advantageously, the system can process soil samples in the “as collected” condition without drying or grinding. The system generally includes a sample preparation sub-system which receives soil samples collected by a probe collection sub-system and produces a slurry (i.e. mixture of soil, vegetation, and/or manure and water), and a chemical analysis sub-system which processes the prepared slurry samples for quantifying multiple analytes and/or chemical properties of the sample. The sample preparation and chemical analysis sub-systems can be used to analyze soil, vegetation, and/or manure samples. A soil collection system is disclosed which captures and directs samples to the sampling system for processing.

1 . A micropump for a microfluidic device, the micropump comprising:
 a first layer;   a second layer adjacent the first layer;   a resiliently flexible diaphragm arranged at an interface between the first and second layers, the diaphragm having a peripheral edge extending perimetrically around the diaphragm; and   a first pump chamber formed on a first side of the diaphragm and a second pump chamber formed on a second side of the diaphragm;   a plurality of restraining tabs protruding radially inwards from the first layer into the first pump chamber;   wherein the restraining tabs abuttingly engage the peripheral edge of diaphragm.   
     
     
         2 . The micropump according to  claim 1 , further comprising an air inlet fluidly coupled to the first chamber, a fluid inlet fluidly coupled to the second pump chamber, and a fluid outlet fluidly coupled to the second pump chamber. 
     
     
         3 . The micropump according to  claim 2 , wherein the restraining tabs are perimetrically spaced apart from each other around a perimeter of the first pump chamber. 
     
     
         4 . The micropump according to  claim 1 , further comprising a circumferential sealing channel recessed into the first layer around a perimeter of the first pump chamber, the sealing channel at least partially receiving the diaphragm therein. 
     
     
         5 . The micropump according to  claim 1 , further comprising a raised annular lip arranged at an inner edge of the sealing channel, the annular lip separating the sealing channel from a main central recess of the first pump chamber. 
     
     
         6 . The micropump according to  claim 1 , further comprising a plurality of anti-stall grooves formed in the second pump chamber. 
     
     
         7 . A method for assembling a micropump for a microfluidic device comprising:
 providing a first layer including a first pump chamber;   positioning a resiliently deformable diaphragm on the first layer above the first pump chamber;   positioning a second layer on the first layer and diaphragm;   compressing the diaphragm between the first and second layers which causes the diaphragm to grow radially outwards; and   engaging peripheral edges of the diaphragm with a plurality of restraining tabs arranged around the first pump chamber to restrain the outward growth of the diaphragm.   
     
     
         8 . A method for preparing a slurry mixture in a microfluidic device, the method comprising:
 providing in the microfluidic device a first micropump, a second micropump fluidly coupled to the first micropump by a first microchannel comprising a microvalve, and a third micropump fluidly coupled to the second micropump by a second microchannel;   each of the micropumps comprising a chamber comprising a pneumatically deformable diaphragm changeable between a closed position for discharging pumping a fluid and an open position for receiving the fluid;   opening a slurry inlet microvalve fluidly coupled to the first micropump;   changing position of the first micropump from the closed position to the open position;   drawing slurry into the first micropump;   closing the slurry inlet microvalve;   opening an extractant inlet microvalve fluidly coupled to the first micropump;   opening an intermediate microvalve disposed in the first microchannel between the first and second micropumps;   changing position of the second micropump from the closed position to the open position;   drawing extractant into the first micropump; and   mixing the slurry and extractant form a slurry-extractant mixture.   
     
     
         9 . The method according to  claim 8 , further comprising drawing the slurry-extractant mixture from the first micropump into the second micropump as a result of changing position of the second micropump from the closed position to the open position. 
     
     
         10 . The method according to  claim 9 , further comprising:
 changing position of the first micropump from the open position to the closed position, and simultaneously changing position of a third micropump from the closed position to the open position, the third micropump fluidly coupled to the second micropump; and   closing the intermediate microvalve between the first and second micropumps; and   changing position of the second micropump from the open position to the closed position which pumps the slurry-extractant mixture into the third micropump.   
     
     
         11 . The method according to  claim 10 , further comprising changing position of the third micropump from the open position to the closed position which pumps the slurry-extractant mixture to an ultrafine filter configured to produce a clear filtered supernatant capable of being chemically analyzed for an analyte in the slurry-extractant mixture.