A portable, stand-alone microfluidic interrogation device including a microprocessor and a touch-screen display. The touch-screen display can receive one or more user input to select a particular particle interrogation procedure, and subsequently show interrogation results. A microfluidic path extending through the interrogation device includes alignment structure that defines an interrogation zone in which particles carried in a fluid are urged toward single-file travel. Operable alignment structure may define sheath-, or non-sheath fluid flow. Desirably, a portion of the alignment structure is removable from the device in a tool-free procedure. The device may operate under the Coulter principle, and/or detect Stokes' shift phenomena, and/or other optically-based signal(s).