Stereolithography (SLA) is a technology commonly used for high resolution desktop 3D printing. SLA is an additive manufacturing process during which the models are produced by illuminating layer after layer of liquid plastic precursor with ultraviolet light. The light initiates a polymerization reaction in the precursor, causing it to solidify. The potential field of applications for SLA is wide, ranging from prototyping industrial parts to bioengineering.
During our research, we used SLA 3D printing to construct an electrochemical flow cell prototype. The cell was optimized and verified to be a suitable device for electroanalysis of live cell suspensions.
The construction of the electrochemical cell is as follows: two main parts produced from plastic resin are connected by a stainless steel tube, which also acts as an auxiliary electrode (counter electrode, CE) in the cell; a platinum working electrode and a Ag/AgCl reference electrode are inserted into specially designed holes in one of the plastic parts; the printed parts have holes at both ends, which have in-built threads for easy and fast connection of rubber tubes and are used to supply the analyzed solution into the electrochemical cell. The flow of the fluid is initiated by a peristaltic pump connected to one of the tubes.
Optimization of the prototype was carried out by measuring the electric signal at different flow speeds, by determining the optimal connecting order of the flow cell components and by finding the correct mediator to be used in the cell.
The prototype of the electrochemical cell was used to analyze a suspension of Saccharomyces cerevisiae cells, which was run through the electrochemical cell in a closed circle and the change of electric current in time was measured with a stable potential applied to the working electrode. A few samples of yeast cells modified by electrically conductive polymer polypyrrole (Ppy) inside their walls were also tested in this prototype. The electrochemical cell was able to measure the different electric signals produced depending on the concentration of the yeast cells and on the concentration of Ppy in the cell walls. These results suggest that an improved version of the prototype may potentially be applicable for industrial uses, such as monitoring in biofuel cells.