Development of an Impedance Spectroscopy Measurement Circuit Board for Protein Detection

This study reports the results on the development of an electrical impedance-based protein detection circuit board for the protein detection biochip. A digital quadrature phase shift module, which can generate two sine waves with 90-degree difference in phase in a large frequency range is employed for lock-in amplifier block for impedance profiling. A microcontroller is used for frequency selection and data acquisition. The measurement module is connected with a computer to display the impedance profile. The implemented board were applied to protein detection biochip to detect the presence of the protein of interest in an essay sample. Experiment is performed for 10 μM Bovine serum albumin (BSA) labeled with fluorescein isothiocyanate (FITC-BSA) protein sample in 10 mM PBS medium solution with the frequency range from 10 kHz to 200 kHz. The measured results reveal a clear impedance change between before and after trapping protein on the microelectrodes of the biochip. The developed electrical impedance spectroscopy board enables rapid and effective protein detection at low concentration.