Laser-induced cobalt oxide entrapment within 3D-printed carbon electrodes for amperometric sensing

The 3D printing technology has the ability to manufacture electrochemical sensors in complex three-dimensional shapes with high efficiency and precision. In parallel, laser scribing technology has been employed to manufacture low-cost and disposable electrochemical sensors. Hence, the combination of both technologies can bring numerous possibilities in the field of electrochemical sensors. The present work addresses the possibility of modifying the surface of 3D printed electrodes through a highly sustainable, practical, and inexpensive route using laser irradiation. For this, a surface modification of a carbon black-based 3D printed electrode was performed using a cobalt chloride solution dropped onto the electrode surface, followed by blue laser irradiation. With this, it was possible to provide an improved electrochemical sensor modified in situ with cobalt oxides, as further attested by physicochemical and electrochemical characterizations. The modified sensor was employed for glucose (GLU) determination using a Batch Injection Analysis (BIA) system. From the modification, the cobalt oxides upon the electrode surface allowed the sensitive detection of GLU in a linear range from 50.0 to 400.0 µmol L⁻¹ and LOD of 6.3 µmol L⁻¹. The GLU analysis in the biological samples yielded recovery values close to 100 %, demonstrating good applicability of the sensor. Thus, the combination of 3D printing and laser scribing technology enabled the production of modified sensors that are highly robust and capable of performing the selective detection of GLU in an easy and simple way.