Implementation
Our solution was implemented using microfluidics, screen-printed electrodes and amperometry.
Microfluidics
Microfluidics refer to systems that control and manipulate fluids in the micron or sub-micron order of volume. They have become increasingly popular in diagnostics due to their portability and convenience, being capable of replacing entire laboratory setups and lowering operating costs.
Four prototype devices were developed to observe the influence of flow rates, perfusate volumes, and flow channel properties on the performance of the SPE using
SOLIDWORKS™2022 and Fusion™360 and 3D-printed in resin, ABS and PLA using the FlashForge™Adventurer 4,
Ultimaker Series 3 and Formlabs Resin Print.
Amperometry measures current due to a redox reaction at an electrode, while a constant or pulsed external electric potential is applied between the working electrode and counter electrode of an electrochemical cell.
As a result of this applied electrical potential, the analyte of interest in the bulk solution moves to the electrical double layer surrounding the working electrode and participates in a redox reaction. This electron transfer creates a current, the value of which depends on the concentration gradient between the bulk solution and electrode surface.
Amperometry
Screen Printed Electrodes
The apparatus used for carrying out chronoamperometric experiments was the Carbon Screen Printed Electrode RRPE1001C from Pine Labs. SPEs are an inexpensive and compact alternative to traditional electrodes, which makes them suitable for microfluidics.
Carbon electrodes were chosen as they offer a larger electrochemical stability window than metals and are safer to use with biological matererial.
Experimental setup
Dopamine solution was pumped through tubing at a fixed rate to the inlet channel of the chip, with a waste collection beaker below the waste outlet. Chronoamperometry was performed, to detect the presence of dopamine in the sample solution, on a Pine Research WaveNow™ Potentiostat.