In the present study, biochar from brewers’ spent grain was used, for the first time, to develop screen-printed electrodes. After having investigated the dispersion behaviour of biochar in different organic solvents, a biochar-based screen-printed electrode was prepared with the drop-casting technique. In order to understand the electrochemical potentiality and performances of the biochar/sensor tool, different electroactive species, i.e., ferricyanide, benzoquinone, epinephrine, ascorbic, and uric acids, were used. The results were compared with those of the same electrodes that were modified with commercial graphene, confirming that the proposed electrode showed improved electrochemical behaviour in terms of resolution, peak-to-peak separation, current intensity, and resistance to charge transfer. Furthermore, a tyrosinase biosensor was developed by direct immobilisation of this enzyme on the biochar/screen printed electrode, as an example of the potential of biochar for disposable biosensor development. The efficiently occurred immobilisation of the biochar on the screen printed electrode’s (SPE’s) surface was demonstrated by the observation of the working electrode with a scanning electron microscope. The detection was performed by measuring the current due to the reduction of the corresponding quinone at low potential, equal to −0.310 V for epinephrine. The experimental conditions for the tyrosinase immobilization and the analytical parameters, such as applied potential and pH of buffer, were studied and optimized. Under these conditions, the electrochemical biosensors were characterized. A linear working range of epinephrine was obtained from 0.05 up to 0.5 mM. The detection limit was 2 × 10⁻⁴ mM for the biosensor.

Biochar is a pyrolytic material with several environmental benefits such as reducing greenhouse gas emissions, sequestering atmospheric carbon and contrasting global warming. However, nowadays, it has moved to the forefront for its conductivity and electron transfer properties, finding applications in the fabrication of electrochemical platforms. In this field, researchers have focused on low-cost biomass capable of replacing more popular and expensive carbonaceous nanomaterials (i.e., graphene, nanotubes and quantum dots) in the realization of sensitive cost-effectiveness and eco-friendly electrochemical tools. This review discusses recent developments of biochar-modified screen-printed electrodes (SPEs). Special attention has been paid to biochar’s manufacturing processes, electron-donating capabilities and sensing applications. Examples of representative works are introduced to explain the distinct roles of biochar in several electro-bioanalytical strategies.

Flexible screen-printing technology modified with nano/material coating boosted the manufacturing of highly sensitive electrochemical sensors for fast and easy-to-handle tests in different application fields.

AI-integrated electrochemical sensors boost peak resolution and sensitivity, enabling precise detection of electroactive species in complex matrices. This method enhances analytical capabilities, providing an analytically robust solution.