title: A lab-in-a-droplet bioassay strategy for centrifugal microfluidics with density difference pumping, power to disc and bidirectional flow control.
abstract: In this paper, we present a lab-in-a-droplet bioassay strategy for a centrifugal microfluidics or lab-on-a-disc (LOAD) platform with three important advancements including density difference pumping, power to disc and bidirectional flow control. First, with the water based bioassay droplets trapped in a micro-channel filled with mineral oil, centrifugal force due to the density difference between the water and oil phases actuates droplet movement while the oil based medium remains stationary. Second, electricity is coupled to the rotating disc through a split-core transformer, thus enabling on-chip real-time heating in selected areas as desired and wireless programmable functionality. Third, an inertial mechanical structure is proposed to achieve bidirectional flow control within the spinning disc. The droplets can move back and forth between two heaters upon changing the rotational speed. Our platform is an essential and versatile solution for bioassays such as those involving DNA amplification, where localized temperature cycling is required. Finally, without the loss of generality, we demonstrate the functionality of our platform by performing real-time polymerase chain reaction (RT-PCR) in a linear microchannel made with PTFE (Teflon) micro-tubing.
authors.affiliation: Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, PR China. ghwang001@gmail.com
authors.forename: Guanghui
authors.initials: G
authors.lastname: Wang
authors.forename: Ho-Pui
authors.initials: HP
authors.lastname: Ho
authors.forename: Qiulan
authors.initials: Q
authors.lastname: Chen
authors.forename: Alice Kar-Lai
authors.initials: AK
authors.lastname: Yang
authors.forename: Ho-Chin
authors.initials: HC
authors.lastname: Kwok
authors.forename: Shu-Yuen
authors.initials: SY
authors.lastname: Wu
authors.forename: Siu-Kai
authors.initials: SK
authors.lastname: Kong
authors.forename: Yiu-Wa
authors.initials: YW
authors.lastname: Kwan
authors.forename: Xuping
authors.initials: X
authors.lastname: Zhang
mesh_terms: D002498:Centrifugation; D004247:DNA / Q000032:analysis; D004560:Electricity; D056656:Lab-On-A-Chip Devices; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D008899:Mineral Oil / Q000737:chemistry*; D060888:Real-Time Polymerase Chain Reaction / Q000295:instrumentation / Q000379:methods; D013696:Temperature; D014867:Water / Q000737:chemistry; D059015:Wireless Technology
chemical_list: D014867:Water; D008899:Mineral Oil; D004247:DNA