Image Number 2 for United States Patent #7189581.
A method is provided of obtaining a sample concentration of a solution in a microfluidic device. The microfluidic device includes a channel having a reservoir and a collection port. The channel is filled with a solution having particles therein. A reservoir drop is deposited over the reservoir of the channel such that the solution of the channel flows towards the collection port in response to evaporation of the solution at the collection port. The particles at the collection port are collected to obtain the sample concentration.