Enhancing the sensitivity of creatinine detection based on resistive switching and strong coupling

Abstract

The present development of reliable creatinine sensors is primarily reliant on the immobilization of the appropriate receptor on the active region of the device. These regions are usually the working electrode and the metallic film for the electrochemical (EC) and surface plasmon resonance (SPR) setups, respectively. This strategy not only raises the cost and complexity of sensor fabrication, but it also complicates regulatory processes. Thus, the aim of this research is to develop alternative sensing techniques based on two physical phenomena: electrochemically produced resistive switching (RS) and plasmonic-induced strong coupling (SC). To accomplish these feats, the material employed must not only meet the requirements for stability, electrical and optical properties, but it must also have affinity for the creatinine molecule. Here, we show that with a simple modification to the commercially available screen-printed electrode with an organic pentamer, BOBzBT2, the RS can be observed and exploited for creatinine sensing applications. Moreover, the addition of BOBzBT2 in the SPR setups along with the utilization of Otto configuration enables the SC regime to be induced. We demonstrate that the SC is sensitive to changes in creatinine concentration. Both BOBzBT2-RS and BOBzBT2-SC sensors demonstrate good linear operating range correspond to the creatinine level in the serum of healthy humans. The limit of detection (LOD) and limit of quantification (LOQ) values for the RS-based sensor are 0.2/0.63 mg/dL and 0.18/0.55 mg/dL, respectively, while the corresponding values for the SCbased sensor are 0.2 and 0.6 mg/dL, respectively. In addition, by combining the thirdorder nonlinear optics theory with the quantum mechanical model of the SC, we present a unique semi-classical theoretical description of the SC phenomenon. A simulation study was also conducted, and the applicability of both theoretical and simulation models was demonstrated by fitting the experimental results. Both sensors exhibited selectivity towards the creatinine molecule over the other investigated analytes in preliminary selectivity validation. As a result of this research, two sensor designs that make use of robust physical processes have been successfully developed. These sensors are appealing owing to their simple manufacturing procedure, high reproducibility, and good sensing performance.