Centrifugal automation of a triglyceride bioassay on a low-cost hybrid paper-polymer device

Abstract

We present a novel paper-polymer hybrid construct for the simple automation of fundamental microfluidic operations in a lab-on-a-disc platform. The novel design, we term a paper siphon, consists of chromatographic paper strips embedded along a siphon microchannel. The paper siphon relies on two main interplaying forces to create unique valving and liquid-sampling methods in centrifugal microfluidics. At sufficiently low speeds, the inherent wicking of the paper overcomes the rotationally induced centrifugal force to drive liquids towards inwards positions of the disc. At elevated speeds, the dominant centrifugal force will extract liquid from the siphon paper strip towards the edge of the disc. Distinct modes of flow control have been developed to account for water (reagent) and more viscous plasma samples. The system functionality is demonstrated by the automation of sequential sample preparation steps in a colorimetric triglyceride assay: plasma is metered from a whole blood sample and incubated with a specific enzymatic mixture, followed by detection of triglyceride levels through (off-disc) absorbance measurements. The successful quantification of triglycerides and the simple fabrication offer attractive directions for such hybrid devices in low-cost bioanalysis

Detection methods for centrifugal microfluidic platforms

“…Godino and colleagues integrated paper in a centrifugal microfluidic platform to route the flow of liquid on the disc (Godino et al, 2013). They demonstrated the use of a paper-based siphon for extracting plasma (Kim et al, 2014) from a whole blood sample.…”

“…For example, a laser that is used for readout could, at the same time, be employed to open valves (Garcia-Cordero et al, 2010). The material used in lateral flow strips can also be employed for valving and liquid routing (Godino et al, 2013). Also, a system which already contains electrical connections for electrochemical sensing could also include electrodes for dielectrophoretic cell separation (Martinez-Duarte et al, 2010) or for measuring flow velocities .…”

Fully Automated Lab-On-A-Disc Platform for Loop-Mediated Isothermal Amplification Using Micro-Carbon-Activated Cell Lysis

“…LOD platforms are attracting considerable attention in microfluidics engineering [ 3 , 4 , 5 , 6 , 7 ]. A typical centrifugal microfluidic technology controls a series of microfluidic operations, such as aliquoting, valving, sample transport, and mixing, by setting the rotational speed and direction [ 8 , 9 , 10 , 11 , 12 ]. Accordingly, centrifugal microfluidic devices control the fluid by generating the required force for fluid propulsion using a single motor.…”

Phase-selective graphene oxide membranes for advanced microfluidic flow control

“…This system was advanced further by integrating the serial siphoning system with a heterogeneous sandwich immunoassay and surface-confined supercritical angle fluorescence (SAF) detection of human immunoglobulin G (hIgG) 10 . Godino et al 11 integrated a paper siphon into a centrifugal LoaD platform, which introduced rotationally controlled bidirectional flow into the system. However, these valving schemes control only the liquid bulk, not its vapor phase.…”