Stereolithography based 3D-printed microfluidic device with integrated electrochemical detection

We demonstrate for the first time the conception of a reusable stereolithography (SLA) based 3D printed separation device with integrated electrodes for electrochemical (EC) detection. For this purpose, a new lab-made working electrode (WE) was developed by 3D-printing a side wall microchannel along the separation microchannel and by inserting a graphite/ resin (C/resin) composite within this side wall microchannel. The 3D-printing conditions of the electrochemical microfluidic device (EMD) as well as the electrode composition, geometry, and integration were optimized for easy and low-cost fabrication (no need for a clean room) and suitable electrochemical response. The electrochemical characterization of the material formulation was first performed in bulk format (disk-shaped, 2 mm diameter) and then moved to the micrometric scale reaching electrode width of 172 ± 12 µm. The integrated electrodes were characterised by voltammetry, and the response linearity of the transducer material was investigated by square wave voltammetry (SWV) using ferrocene methanol (FcMeOH). The C/resin electrode led to a good repeatability (RSD of ± 2% ( n  = 3) in the peak current values), linear response (R 2  = 0.995) in the 15 − 1000 µM range, allowing for limits of detection and quantification of 4.5 µM and 15 µM, respectively. In order to develop a complex analytical device, the interest of this dedicated device was evidenced in a hydrodynamic state condition with Ru(NH 3 ) 6 3+ as a proof-of-concept, ranging from 0 to 55 µL min −1 mimicking the electroosmotic flow conditions, which is a bulk liquid motion very common in electrically driven separation techniques.