CMOS Multi-electrode Biosensors: DNA Detection

There is an urgent need for rapid on-the-spot diagnosis of infectious diseases like HIV. A very common diagnostic method includes the use of fluorescence-based DNA analysis on micro-arrays after preceding DNA amplification (PCR). In collaboration with Prof. J. Janata, Georgia Institute of Technology we are working towards a simple, label-free, exclusively electronic method to detect hybridization events in order to obviate the need for large optical setups.

The measurement principle relies on cyclic voltammetry (CV) producing I-V curves, the shape of which depends on the electrochemistry occurring at the electrode surface (see Figure). The platinum electrodes are covered with an electropolymer (polypyrrole), which is cyclically oxidized and reduced. The kinetics of the chloride counterion exchange with the liquid phase upon this redox cycling are affected by the presence and concentration of negatively charged phosphate groups on the DNA strands. The number of these negative charges in close electrode vicinity increases upon hybridization. The kinetics of the ionic travel and, consequently, the shapes of the CV curves, are consequently altered through hybridization.

This electrochemical DNA sensing method has been miniaturized by developing a monolithic CMOS system carrying 516 electrodes and the needed potentiostats on the same chip. The analog-to-digital conversion is also done on chip.

Outlook

The aim is to develop a low-cost, label-free, and purely electronic DNA detection array for field and point-of-care usage.

Publications

• M.K. Lewandowska, J. Rothe, F. Heer, M. Josowicz, J. Janata, A Hierlemann, "Characterization of label-free DNA hybridization sensor array in CMOS technology", Proceedings 20th Anniversary World Congress on Biosensors, May 26-28, 2010, Glasgow, United Kingdom, P3.1.059.
• F. Heer, M. Keller, G. Yu, J. Janata, M. Josowicz, A. Hierlemann, "CMOS electro-chemical DNA detection array with on-chip ADC", Proceedings of the IEEE, ISSCC, San Francisco, USA, 2008, p. 168, 169, and 604, ISBN: 978-1-4244-2010-0.

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Collaborations

Georgia Institute of Technology, Atlanta, USA.

Contact

Dr. Olivier Frey