3D hydrodynamic focusing History of engineering & technology aperture ratio biosensor cells colored oil colorimetric method colorimetry dissolved oxygen driving waveform droplet microfluidics electro-fluidic display electrowetting display fabrication hysteresis characteristic ink distribution lab-on-a-chip laser induced fluorescence liquid-core waveguide mechanical properties micro-manipulation micro-thermometry micro/nanomaterials microfluidic microparticles microreactor microscale channel nanofluidic nanohole array nanoplasmonic