Integrating electrochemical detection with centrifugal microfluidics for real-time and fully automated sample testing

Abstract

Abstract. Here we present a robust, stable and low-noise experimental set-up for performing electrochemical detection on a centrifugal microfluidic platform. By using a low-noise electronic component (electrical slipring) it is possible to achieve continuous, on-line monitoring of electrochemical experiments, even when the microfluidic disc is spinning at high velocities. Automated sample handling is achieved by designing a microfluidic system to release analyte sequentially, utilizing on-disc passive valving. In addition, the microfluidic system is designed to trap and keep the liquid sample stationary during analysis. In this way it is possible to perform cyclic voltammetry (CV) measurements at varying spin speeds, without altering the electrochemical response. This greatly simplifies the interpretation and quantification of data. Finally, real-time and continuous monitoring of an entire electrochemical experiment, including all intermediate sample handling steps, is demonstrated by amperometric detection of on-disc mixing of analytes (PBS and ferricyanide).

Detection methods for centrifugal microfluidic platforms

“…Electrochemical sensing on a centrifugal microfluidic platform was implemented already in 1982 (Cho et al, 1982), and since then other studies have used an electrical component transferring the electrical signal to/from a stationary readout unit to the rotating disc with electrodes and contact pads Andreasen et al, 2015;Kim et al, 2013). This approach typically entails the use of either carbon brushes sliding across a metal ring (slip ring) or a mercury-based rotating electrical connector.…”

“…Andreasen and coworkers (Andreasen et al, 2015) developed a During impedance measurements, adsorption and binding of cells or biomolecules results in decrease of the electrode capacitance, and therefore, an increase of the overall electrochemical cell impedance is measured. Nwankire and colleagues (Nwankire et al, 2015) demonstrated impedance-based measurements on a centrifugal platform to detect cancer cells from a mixture of cancer cells and blood .…”

The eLoaD platform endows centrifugal microfluidics with on-disc power and communication

“…Analyte detection and quantification (eg. cancer cells detection (Nwankire et al, 2012(Nwankire et al, , 2015 or CRP using an ELISA assay (Kim et al, 2013), glucose concentration by using the amperometric measurement of ferricyanide ion (Cho et al, 1982;Andreasen et al, 2015;Rattanarat et al, 2015) or uric acid, and lactate levels (Li et al, 2013)). Flow analysis (eg.…”

“…There have been a few pioneer publications reporting on centrifugal microfluidic systems in which power is transferred to the spinning platform, such as by using slip-rings (Cho et al, 1982;Martinez-Duarte et al, 2010;Abi-Samra et al, 2013;Kim et al, 2013;Andreasen et al, 2015), or even wirelessly (Burger et al, 2011;Wang et al, 2013), allowing the mounting of electric components in direct contact with the microfluidic disc without the need of stopping it. Nevertheless, the platforms were built and used for a specific application, and thus hard to reconfigure for use in other applications.…”

Lab-on-a-CD: A Fully Integrated Molecular Diagnostic System

“…155 In this detection scheme, three electrodes are typically used: a working electrode, a reference electrode, and an auxiliary electrode. An electrical potential is applied between the working electrode and the reference electrode.…”