Fully electronic CMOS DNA sensor chip

This work reports the realization of a fully integrated innovative microsystem for DNA detection. The sensor system makes use of direct electrical detection by means of an electrochemical method. Electrochemical detection is characterized by features like excellent sensitivity, high level of integration and reduced system costs. Due to these features, the electrochemical detection is believed to have a promising potential to replace the conventional optical methods. A basic modelling of the fundamental physical processes regarding the electrochemical detection was utilized for the design of the transducer element and the electronic sensor circuitry interacting with electrochemical reactions. Pixel circuits were designed which bias the electrochemical reactions and process the resulting electrical signals at each sensor position. A potentiostat circuit was implemented to control the potential of the analyte and to ensure proper electrochemical operation. Various peripheral circuits were designed for easy system operation and chip interfacing. The electronic sensor and readout circuitry are realized as an ASIC. The new approach is based on a standard CMOS technology with additional process steps for formation of electrochemical transducer electrodes. Prototype sensor array chips with up to 128 positions were designed, fabricated, characterized by using a built-in electrical test mode and were operated with biological material to demonstrate system functionality.