Size-Dependent Filtration and Trapping of Microparticles in a Microfluidic Chip Using Graduated Gaps and Centrifugal Force

Abstract

We proposed size-dependent microparticle filtration and trapping using graduated microchannel gaps and centrifugal force using a three-dimensional magnetically driven microtool (3D-MMT) in a microfluidic chip made of polydimethylsiloxane (PDMS). Our paper contributes the following to the field: (1) Particle filtration is robust against pressure fluctuation due to tube vibration between the chip and pump. (2) Clogging by microparticles is avoided by rotating the 3D-MMT in a microchamber. (3) Size-classified microparticles are trapped by flow control along microchannel gaps. Different-sized microparticles flow in spiral microchannels and are filtered based on size between gaps and the substrate by centrifugal force. Microparticles larger than gaps remain in the inner microchannel. Rotating the 3D-MMT using an external magnetic circuit generates swirling flow in the microchamber. Size-classified microparticles are trapped in microchannels by closing the drain port for the targeted particle. Trapped particles are measured by direct observation and treated by reagent. After experiments, trapped particles are extracted by opening drain ports. We demonstrated microparticle filtration and microparticle trapping in the microfluidic chip.