The present invention is generally directed to methods, apparatus and systems for use in performing in situ dilution or concentration of a particular subject material in a microfluidic device or system. These methods and apparatus may generally be integrated with other microfluidic operations and/or...http://www.google.com/patents/US6475441?utm_source=gb-gplus-sharePatent US6475441 - Method for in situ concentration and/or dilution of materials in microfluidic systems
