A CMOS integrated cell adhesion sensor for lab-on-a-chip applications

Cell-based assays for environmental monitoring enable quick information about a broad spectrum of possible contaminations. A key parameter that conveys information about the state of the cell culture is its electrical impedance, representing the amount of cell adhesion and morphological changes. We present a novel sensor for cell impedance measurements designed for application in a multi-parameter cell chip based on CMOS technology. A primary goal in the development of the sensor was keeping its interface to the external world as simple and robust as possible. This was achieved by integrating the sensor front-end electronics in close physical proximity to the sensing site. The result is a CMOS impedance-to-frequency converter with digital square wave output. A test chip featuring an array of 64 sensing microelectrodes, each addressable by a digital interface, was fabricated in a standard CMOS technology supplemented with a backend process for planar gold electrodes. We present measurement results with cells that demonstrate the successful operation of the system and its ability to capture changes in the cells' impedance caused by the model toxin cytochalasin.