A New Low Power Instrument for Impedance Measurements in Biomedicine Based on FFT. Application to Interleukin-10 Protein Detection☆

Abstract We describe a low power, easy to use and portable device for measuring the electrochemical impedance of different types of biosensors. The measurement technique is based on the direct synthesis of sinusoidal signals followed by a discrete time Fourier transform analysis, carried out by an integrated electronic stage that excites and collects the response from the sample. This kind of technique provides very good signal to noise ratio, high sensibility to small variations in the sensor impedance and high accuracy and reliability. The device was tested studying the sensor response at different frequencies of a gold microelectrode, fabricated through a combination of soft lithography tools, capable of monitoring the antibody-antigen concentration for the Interleukin 10 (IL-10). Our custom design makes possible extending the current range down to the pA, with accuracy better than 1%, and optimizing the power consumption to reach figures under 150 μW per measurement.