Two-dimensional materials may constitute key elements in the development of a sensing platform where extremely high sensitivity is required, since even minimal chemical interaction can generate appreciable changes in the electronic state of the material. In this work, we investigate the sensing performance of epitaxial graphene on Si-face 4H-SiC (EG/SiC) for liquid-phase detection of heavy metals (e.g., Pb). The integration of preparatory steps needed for sample conditioning is included in the sensing platform, exploiting fast prototyping using a 3D printer, which allows direct fabrication of a microfluidic chip incorporating all the features required to connect and execute the Lab-on-chip (LOC) functions. It is demonstrated that interaction of Pb²⁺ ions in water-based solutions with the EG enhances its conductivity exhibiting a Langmuir correlation between signal and Pb²⁺ concentration. Several concentrations of Pb²⁺ solutions ranging from 125 nM to 500 µM were analyzed showing good stability and reproducibility over time.

Two arrangements of the experimental setup were developed by using two different sample holders: glass cuvettes and 3D printed fluidic chips. In the 3D chip configuration, using two programmable syringe pumps, several ATP concentrations were measured in continuous-flow mode by simply changing the flow-rate ratio of the reactants (ATP and standard reaction solution).

Adenosine triphosphate (ATP) bioluminescence has been widely used for biosensing applications. Commercially available platforms to perform biological testing are expensive, bulky, and require substantial amounts of reactants. Here, we report design, fabrication and testing of low cost 3D printed microfluidic chips coupled with silicon photomultipliers (SiPMs) for high sensitive real-time ATP detection. Bioluminescence current increases with increasing ATP concentration in the monitored range. The system is very sensitive to ATP concentration changes regulated by the flow rate. It exhibits a sensitivity of 1.82·10-2 A/M and a LoD of 8 nM. Static and dynamic performance of the SiPM for ATP bioluminescence detection were evaluated by measuring different ATP concentrations. They were carried out coupling SiPM with a glass cuvette and a 3D-chip as sample holders, respectively. Using 3D-chip and two programmable syringe pumps, several ATP concentrations could be measured in continuous-flow mode by simply changing the flow-rate ratio of the reactants (ATP and standard reaction solution). The ability of the SiPM to detect the weak bioluminescence signals emitted by low ATP concentration. To demonstrate the sensitivity and the improved performance of this SiPM-based system, same ATP concentrations were measured and compared with a commercial reader (PerkinElmer Victor 2030). The calibration curve comparison, demonstrates as all systems compared exhibit similar sensitivities within the experimental errors. The combination of SiPM with 3D-chips provides a means of creating compact, sensitive and low-cost bioluminescence systems with wide-ranging applications in chemical and biological analysis. The continuous-flow analysis, combined with the compactness of the system, may allow its positioning directly inside environmental chambers, thus facilitating sample study in real time during growth.