Petra Schindler-Bauer

Design of an integrated potentiostat circuit for CMOS bio sensor chips

A design strategy is presented for potentiostat circuits suitable for electronic bio sensors on CMOS. Guidelines are given to guarantee stable operation under the condition of widely varying and only roughly known electrochemical parameters. A concrete design example used in a fully electronic DNA sensor array CMOS chip is shown. Measurement results with a biological analyte applied to that chip prove proper operation of the potentiostat.

A digital CMOS DNA chip

A fully electronic medium density DNA micro array is presented using a CMOS process extended by gold electrodes. The chip provides 128 sensor sites, in-sensor site current-mode A/D conversion, peripheral circuitry including bandgap and current references, D/A-converters to provide electrode bias voltages, calibration circuitry, and a 6 pin interface for power supply and serial digital data transfer.

Passive DNA Sensor with Gold Electrodes Fabricated in a CMOS Backend Process

A sensor for electrical detection of DNA is fabricated in a CMOS production line. A gold deposition process module is integrated in a CMOS backend process. The sensor principle is based on immobilization of singlestranded DNA probe molecules on an array consisting of interdigitated gold lines and subsequent hybridization with labeled target DNA strands. The electrical signal results from an electrochemical redox cycling process. Successful DNA detection experiments on the basis of such ‘passive’ chips are performed. This passive arrangement represents a test run for the extension of this principle to develop fully electronic DNA sensor arrays on active CMOS chips.

CMOS-Based Biosensor Arrays

CMOS-based sensor array chips provide new and attractive features as compared to todays standard tools for medical, diagnostic, and biotechnical applications. Examples for molecule- and cell-based approaches and related circuit design issues are discussed.

A CMOS Medium Density DNA Microarray with Electronic Readout

A CMOS chip-based approach is reviewed for fully electronic DNA detection. The electrochemical sensor principle used, CMOS integration of the required transducer materials, chip architecture and circuit design issues are discussed, respectively. Electrochemical and biological results obtained on the basis of medium density microarray sensor CMOS chips with 16 × 8 sensor sites prove proper operation.

CMOS Sensor Interface Arrays for DNA Detection

Sensor arrays for fully electronic DNA detection based on an extended CMOS process are discussed. An introduction to the used DNA detection method and to the modified CMOS process is given, and special emphasis is put on design issues of circuit blocks whose function is particularly related to the electrochemical operation principle of the chip. Stability and accuracy aspects are considered in detail. Measured data are shown from electrical characterizations as well as from biological experiments.