The Gate-Modified Solution-Gated Graphene Transistors for the Highly Sensitive Detection of Lead Ions

Lead ions are heavy metal ions that are extremely harmful to the human body and ecological environment. They can cause irreversible damage to the human nervous system and blood system at low concentrations. It is very important to develop a simple, rapid, and sensitive detection method of Pb2+. Solution-gated graphene transistors (SGGTs) have been widely studied in recent years due to their ultra-high sensitivity in chemical sensing. Herein, we have demonstrated a sensitive sensor of Pb2+ based on the SGGTs through the glutathione gate modification. When Pb2+ are added into the electrolyte solution, the electrical double layer capacitance near the gate electrode changes because Pb2+ can be strongly chelated, leading to the channel current change. The detection of Pb2+ can be realized. The detection limit of sensors for Pb2+ can reach 1 × 10-18 M, and the response time is about 1 s. The channel current change and the logarithm of Pb2+ concentration exhibit a good linear relationship in the concentration range of 1 × 10-18 and 1 × 10-6 M. Because the glutathione molecule can well recognize Pb2+, the devices also demonstrate good selectivity to Pb2+. Compared with the convention detection, our method shows easy operation, high sensitivity, and high selectivity. Therefore, it has great potential in the analysis of trace samples for health and environment monitoring.