Our group has previously reported a system for three-dimensional particle focusing using chevron-shaped grooves that is robust, simple to fabricate, and compact. Recently, the technology was incorporated into a microflow cytometer system to identify fluorescence-coded microspheres and display the formation of antibody-antigen complexes. The microflow cytometer focused the microspheres in three dimensions within a laser interrogation region using the passive groove structures to surround the sample stream with sheath fluid. We are extending the technology to include automated sample processing for point-of-care diagnostics and biothreat detection. Another version of the microflow cytometer is under development for identifying marine algae on unmanned underwater platforms.