Radio-Frequency Electrochemical Sensor Arrays for Biological Imaging

Abstract

Cells and tissues have subtle and complex electrical properties, but it can be challenging to access these properties at fine spatial and temporal resolution. Custom CMOS microelectronics can offer some solutions, but planar electrodes are always limited by Debye screening, which causes traditional low-frequency impedance spectroscopy at physiological conditions to be sensitive to chemical conditions within only a few nanometers of the working electrode. Radio frequency dielectric spectroscopy can enable measurements of features farther from the surface, but this sensing regime remains under-explored, in part due to the challenge of designing microelectronics with suitably low noise, high bandwidth, high density, and low parasitics. We have fabricated prototype integrated CMOS sensor arrays which can produce electrochemical images at 100 MHz, using dense arrays of thousands of micrometer-scale pixels. These sensor arrays can also be combined with other chemical and optical sensor elements, for rich multi-modal biological imaging.