Method and Apparatus for Trapping Single Particles in Microfluidic Channels

Abstract

Methods and apparatus for improving measurements of particle or cell characteristics, such as mass, in Suspended Microchannel Resonators (SMR's). Apparatus include in particular designs for trapping particles in SMR's for extended measurement periods. Methods include techniques to provide differential measurements by varying the fluid density for repeated measurements on the same particle or cell.

What is claimed is: 
     
         1 . A Method for measuring density of a particle in an SMR with a particle trap, comprising;
 introducing at least one particle into the SMR in a fluid of a first density,   trapping a particle in the particle trap,   changing the density of the fluid at least once; and,   computing the density of the particle by observing the difference of the resonant behavior of the SMR at different fluid densities.   
     
     
         2 . The method of  claim 1  wherein the changing step comprises mixing a fluid of a second fluid density with the fluid of the first density at at least one mixing ratio.