High-frequency impedance spectroscopy at CMOS nanocapacitor arrays

Electrochemical biosensors are attractive due to their ease of integration, miniaturization and cost-effective parallelization. However, electrical detection in liquid is severely hindered by screening due to mobile salt ions. For example, under physiological conditions, the electrostatic sensing of a target analyte further than a few nanometers from an electrode is essentially impossible. High-frequency signals can overcome this problem by outrunning ionic screening, but are challenging to implement due to the inevitable stray capacitance. In this thesis, we employ a large-scale, high-density array of nanoelectrodes integrated with standard CMOS electronics on a single chip to perform high-frequency impedance spectroscopy measurements. The device provides a tool to explore experimentally new regimes of the spectra that were unreachable with nanoelectrodes up to now, making this the main aim of the research.