Method and apparatus for point of care osmolarity testing

Abstract

An apparatus and a method are disclosed for providing point of care testing for osmolarity of a bodily fluid. An apparatus is disclosed as having a fluid pathway passing through it for receiving and testing a sample fluid. The invention permits osmolarity testing of a sample fluid wherein the sample fluid has a volume of less than approximately 30 nL, and implements a method and device to measure fluid osmolarity in a clinical setting quickly and accurately, while also reducing evaporation of the fluid.

1 . A method for determining osmolarity of a sample fluid, comprising the steps of: 
 communicating a sample fluid through a conduit fixed to a base member directly to a sample receiving chip; and    determining osmolarity of the sample fluid.    
   
   
       2 . The method of  claim 1 , wherein the sample receiving chip includes: 
 a substrate having a fluid pathway passing through the substrate for receiving a sample fluid, the fluid pathway including a first port, at least one second port, and a recessed channel, the recessed channel enclosed in the substrate; and    at least two electrodes cosintered with multilayer ceramic positioned in the substrate to contact the sample fluid in the recessed channel to measure properties of the sample fluid.    
   
   
       3 . The method of  claim 1 , wherein the step of communicating includes applying an external pressure to a base unit, the base unit including a chamber for receiving a first end of the conduit, wherein the chamber includes a substantially flexible partition.  
   
   
       4 . The method of  claim 1 , wherein the step of determining the osmolarity of the sample fluid includes measuring the conductivity of the sample fluid to obtain a conductivity value and converting the conductivity value to a corresponding osmolarity value.  
   
   
       5 . The method of  claim 1 , wherein the communicating step includes contacting an in vivo sample of bodily fluid on the human eye, whereby the sample fluid is drawn into the conduit by capillary force.