A Molecular Imprinted Polymer Tethered Capacitive Sensor for Epicatechin Detection in Green Tea

In this study, a stable, selective, reusable, and economic capacitive sensor has been fabricated by implementing molecular imprinted polymer (MIP) technology for the detection of epicatechin (EC) in green tea. A molecular imprinted polydopamine-polyethylene glycol (PDA-PEG) composite deposited on a copper-cladded FR-4 plate is considered the sensing material of the proposed sensor. Scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques were used for the characterization of the synthesized materials. The variation of capacitance
${C}_{P}$
as a function of frequency for MIP-EC capacitive sensor (MIP-EC@C) and nonimprinted polymer-based capacitive sensor (NIP@C) was explored in this study. The linear range of operation was observed at 5–20 ppm with a lower limit of detection (LOD) found to be 1.07 ppb. Two linear regression models were used to predict the EC content of green tea samples. The prediction accuracy of 99.56% is obtained using the principal component regression (PCR) method and that of 99.51% using partial least square regression (PLSR). The root-mean-square error of calibration for both PLSR and PCR was 0.003 using four and five latent variables, respectively. The electrode exhibited a fairly stable behavior, and even after 100 days, the performance of the sensor hardly degraded as only a 0.7% (appropriately) increase in maximum capacitance was observed.