With the advent of disposable carbon-based electrodes, the development of sensors and biosensors has become much more accessible. The techniques normally used to fabricate disposable carbon-based electrodes are screen-printing and inkjet printing. However, both techniques are costly and involve time-consuming operations¹. In this work, a new, fast, and cost-effective prototyping process has been developed for the fabrication of disposable carbon-based electrochemical cells (DCell) using a simple procedure based on use of a cutter printer for prototyping and laminating. The layout of the homemade all-plastic carbon electrodes, comprising a working electrode (WE), a pseudo- reference electrode (RE), and a counter electrode (CE), was drawn using Silhouette Studio v. 2.7.4 software. The pattern was transferred to an adhesive vinyl film using an electronic craft cutter (Silhouette Cameo, Silhouette America, Inc.). The undesired portions were peeled off using tweezers, leaving the template of the electrochemical cell as a negative mask. Next, the vinyl with the template was attached to a polyester sheet (transparency film for laser printers, purchased in a local market) with dimensions of 21.0 cm × 29.7 cm. The carbon ink was then transferred using a squeegee, in three steps. First, the carbon ink (C2030519P4, Gwent Electronic Materials Ltd, UK) was poured onto the top of the vinyl mask surface and dragged across the template using the squeegee, resulting in ink deposited onto the polyester sheet with an average of 80 μm thickness (Figure 1). After curing the ink for 30 min at 60 ºC, Ag/AgCl ink (C2051014P10, Gwent Electronic Materials Ltd, UK) was deposited as the pseudo-reference electrode and then cured for 30 min at 60 ºC. After this, the vinyl mask was removed. Finally, a lamination process was used to define the geometric area and insulate the electrodes. This involved the use of a laminating pouch (purchased locally) consisting of a sheet of transparent polyester covered with a thin layer of polyethylene. The pouch was appropriately cut, using the cutting printer, and placed onto the polyester sheet with the screen-printed electrodes, followed by application of heat and pressure using a heater press. The DCell was applied in the determination of toxic metals in water samples, in the detection of NADH and Salmonella and, in the interaction of bisphenol A with DNA. The device showed excellent performance in the applications. Using the proposed method, hundreds of carbon based electrochemical cells could be assembled in less than two hours, at a materials cost of less than US$ 0.02 per cell. The new proposed prototyping process opens up new avenues for the development of disposable electrochemical devices for applications as sensors and biosensors.

Acknowledgments: This work was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, Proc. No. 2012/09752-2, 2012/24079-2, and 2013/06750-1) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Proc. No. 474110/2013-3).

1. N. Thiyagarajan, J.-L. Chang, K. Senthilkumar, and J.-M. Zen, Electrochem. commun., 38, 86–90 (2014) http://www.sciencedirect.com/science/article/pii/S1388248113004451.