Portable High-Accuracy Wireless Acquisition System for Graphene-Based Sensors

Graphene-based field-effect transistors (gFETs) are gaining popularity for the realization of biological sensors as their graphene active area provides a convenient basis for attaching organic substances, such as appropriately engineered receptors. The presence of a particular biological agent then translates in the modification of the electrical characteristics of the gFET. We thus developed a compact, portable system that is able to accurately measure those electrical characteristics with high accuracy, by automatically compensating its own offsets and errors. The acquisition device we here present is able to measure drain currents with a nominal accuracy of 0.1% and with an rms noise as low as 22 pA, up to a maximum of $125 \mu \text{A}$ (22 bits effective resolution), and gFET channel resistances with a nominal accuracy of 0.01% $\pm 0.1 \Omega $ and with an rms noise as low as $2.13 \mu \text{V}$ in the range from $100 \Omega $ to 1 $\text{M}\Omega $ . Due to its performance, small dimensions, and long battery life, it can be used both for scientific research, where portability and ease of use are key features when operating in potentially hazardous environments due to the presence of biological agents, and as a fully automated detector when coupled with the appropriate sensor, as it can perform thousands of measures on a single battery charge and be completely remotely controlled over a Bluetooth low energy (BLE) connection.