60µW high precision fully integrated in-vivo impedance spectroscopy using synchronous detection of magnitude and phase

This work presents a fully integrated, high precision and low power readout front end for in vivo Electrochemical Impedance Spectroscopy applications. The operation is based on the digital synchronous detection of the magnitude and phase shift. This is enabled using a compact and fully integrated sinusoidal signal generator to produce the interrogation frequencies that are injected into the testing sample. The readout system includes an asynchronous measurement mode at high frequencies to reduce the error. It also offers a simple structure with low component count making it suitable for biomedical implants and integration in array structures. The system is designed and simulated on a 45 nm CMOS process and consumes 60µA at a 1 V supply. It can measure the impedance over a frequency range from 1mHz to 100 kHz.