An integrated microfludic chip with continuous flow centrifugation for sample concentration, particle collestion and particle transport

Abstract

Biological sample concentration in a large volume is essential to bio-analyses of environmental samples. If particles in drinking water can be high-throughput concentrated, collected and transported into a bio-analysis system easily, an automatic online monitoring system of drinking water can be developed. The present work aims to design and fabricate a chip with single channel to achieve continuous flow centrifugation of particles in water sample with integrated capability of droplet based particle collection and particle transport to downstream functional modules on the same chip, such as a cell sorter or a PCR system. Two methods of integrated continuous flow centrifugation, namely the Point Capture method and the Distributed Surface Capture method, have been proposed and investigated. A J-channel chip is designed for the application of the Point Capture method, and a spiral channel chip is designed for the application of the Distributed Surface Capture method. For fluorescent bead suspension, our prototype of the J-channel chip is able to achieve a concentrating efficiency ranged between 50% and 93% with a trend for higher concentrating efficiency at a lower feed rate (feed rate between 5-20 mL/h). Our spiral channel chip is able to achieve a concentrating efficiency ranged between 50% and 100% with a trend for higher concentrating efficiency with a lower feed rate (feed rate between 60-180 mL/h). The continuous concentration and collection of E. coli cells in the J-channel chip are also demonstrated. The integration between the sample concentration, the droplet based particle collection and downstream functional modules such as micro-reactors has also been achieved.