Electric Field-Enhanced SPR Sensors with AuNPs and CQDs for Rapid and Low-Detection-Limit Detection of Co2+

As a vital transition metal species, cobalt ions (Co2+) play a critical role in industrial and medical fields. However, uncontrolled release into ecosystems via industrial effluents presents significant environmental risks. To address this, a prism-coupled surface plasmon resonance (SPR) sensor chip was developed which enables simultaneous high sensitivity, wide detection range, and rapid detection of Co2+ under ultra-low detection limit conditions. By depositing a 50 nm Au film and AuNPs on a glass substrate, and integrating carboxyl-functionalized carbon quantum dots (CQDs), the chip achieved the detection range of 10−20 mol/L to 10−4 mol/L, and the response time was reduced from 21 min to 11 min under optimal electric field conditions (1.2 V, 0.15 mol/L electrolyte concentration). The sensor exhibits high selectivity, repeatability, and stability. It can be integrated with optofluidic technology to enable high-throughput microfluidic analysis, thereby facilitating further advancements in related research.