@article{Franks2005,
title = {Impedance characterization and modeling of electrodes for biomedical applications},
author = {Wendy Franks and Iwan Schenker and Patrik Schmutz and Andreas Hierlemann},
url = {http://ieeexplore.ieee.org/document/1440608/},
doi = {10.1109/TBME.2005.847523},
issn = {00189294},
year = {2005},
date = {2005-06-13},
journal = {IEEE Transactions on Biomedical Engineering},
volume = {52},
number = {7},
pages = {1295-1302},
abstract = {A low electrode-electrolyte impedance interface is critical in the design of electrodes for biomedical applications. To design low-impedance interfaces a complete understanding of the physical processes contributing to the impedance is required. In this work a model describing these physical processes is validated and extended to quantify the effect of organic coatings and incubation time. Electrochemical impedance spectroscopy has been used to electrically characterize the interface for various electrode materials: platinum, platinum black, and titanium nitride; and varying electrode sizes: 1 cm2, and 900 mu m2. An equivalent circuit model comprising an interface capacitance, shunted by a charge transfer resistance, in series with the solution resistance has been fitted to the experimental results. Theoretical equations have been used to calculate the interface capacitance impedance and the solution resistance, yielding results that correspond well with the fitted parameter values, thereby confirming the validity of the equations. The effect of incubation time, and two organic cell-adhesion promoting coatings, poly-L-lysine and laminin, on the interface impedance has been quantified using the model. This demonstrates the benefits of using this model in developing better understanding of the physical processes occurring at the interface in more complex, biomedically relevant situations.},
keywords = {MEA Technology},
pubstate = {published},
tppubtype = {article}
}

@article{Jenkner2004,
title = {Cell-based CMOS sensor and actuator arrays},
author = {Martin Jenkner and Marco Tartagni and Andreas Hierlemann and Roland Thewes},
url = {http://ieeexplore.ieee.org/document/1362853/},
doi = {10.1109/JSSC.2004.837082},
issn = {00189200},
year = {2004},
date = {2004-11-30},
journal = {IEEE Journal of Solid-State Circuits},
volume = {39},
number = {12},
pages = {2431-2437},
abstract = {In recent years, increasing knowledge about in vitro cell handling and culturing has encouraged a variety of CMOS-based approaches to stimulate and detect electrical activity of biological cells. This paper outlines in a topical review the scope of cell-based biosensors and actuators for in vitro applications ranging from single-cell detection to multisite probing of complex neural tissue. Recent examples are selected to demonstrate how standard CMOS processes have been used to engineer arrays with different functionality.},
keywords = {MEA Technology, Review},
pubstate = {published},
tppubtype = {article}
}

@article{Baltes2004,
title = {CMOS microelectrode array for the monitoring of electrogenic cells},
author = {Flavio Heer and Wendy Franks and Axel Blau and S Taschini and Christiane Ziegler and Andreas Hierlemann and Henry Baltes},
url = {http://www.sciencedirect.com/science/article/pii/S0956566304000806?via%3Dihub},
doi = {10.1016/j.bios.2004.02.006},
issn = {0956-5663},
year = {2004},
date = {2004-03-19},
journal = {Biosensors & Bioelectronics},
volume = {20},
number = {2},
pages = {358-366},
abstract = {Signal degradation and an array size dictated by the number of available interconnects are the two main limitations inherent to standalone microelectrode arrays (MEAs). A new biochip consisting of an array of microelectrodes with fully-integrated analog and digital circuitry realized in an industrial CMOS process addresses these issues. The device is capable of on-chip signal filtering for improved signal-to-noise ratio (SNR), on-chip analog and digital conversion, and multiplexing, thereby facilitating simultaneous stimulation and recording of electrogenic cell activity. The designed electrode pitch of 250 mu m significantly limits the space available for circuitry: a repeated unit of circuitry associated with each electrode comprises a stimulation buffer and a bandpass filter for readout. The bandpass filter has corner frequencies of 100 Hz and 50 kHz, and a gain of 1000. Stimulation voltages are generated from an 8-bit digital signal and converted to an analog signal at a frequency of 120 kHz. Functionality of the read-out circuitry is demonstrated by the measurement of cardiomyocyte activity. The microelectrode is realized in a shifted design for flexibility and biocompatibility. Several microelectrode materials (platinum, platinum black and titanium nitride) have been electrically characterized. An equivalent circuit model, where each parameter represents a macroscopic physical quantity contributing to the interface impedance, has been successfully fitted to experimental results.},
keywords = {ETH-CMOS-MEA, MEA Technology},
pubstate = {published},
tppubtype = {article}
}