Integrated Multi-Electrode Arrays for Biointerfaces
Multi-electrode arrays (MEA) emerged in recent years as a viable alternative for recording electrical activities of (biological) cells to more established in-vitro techniques like patch clamps. MEAs provide the opportunity for extracellular recording and stimulations of electrically-active cells like cardiomyocytes (heart muscle cells) and neurons.
Integrating a MEA with analog-to-digital/digital-to-analog conversion and channel multiplexing to provide an effective solution for these biointerfaces is the topic of the work carried out together with Flavio Heer, Sadik Hafizovic, Wendy Franks, and Andreas Hierlemann of the Physical Electronics Laboratory at the ETH Zurich. The chip on the right shows a proof-of-concept of this approach, featuring a 4x4 electrode array.
See the publications and the references therein for further information.
Integrated Hotplates for Gas Sensing
Gas sensors based on hotplates are particularly suited for detecting carbon monoxide, ozone, nitrogen oxide, hydrogen or hydrocarbons. Molecules of these gases are detected when entering the porous structure of the heated metal oxide (typically tin or indium oxide) that is used as sensitive layer. The metal oxide is doped with noble metals and exhibits a semiconductor behavior. The presence of gas molecules alters the conductivity of the sensitive layer and can therefore be detected by resistance measurement.
As the resistance is very sensitive to temperature changes, the temperature of the hotplate is controlled in closed loop. A single-chip solution like that depicted here on the left integrates the hotplate, readout electronics, and the thermostat in one silicon die, and is therefore suitable for large-volume production. This work has been carried out together with Diego Barrettino, Markus Graf and Andreas Hierlemann of the Physical Electronics Laboratory at the ETH Zurich.
See the publications and the references therein for further information.
Numerical and Symbolic Modeling for MEMS and Microelectronics
Finite-element and boundary-element methods allow the designers of Micro-Electro-Mechanal Systems (MEMS) to optimize their structure for maximum performance. A software framework written in C++ and, later, a set of Mathematica® packages form a set of tools that have been developed to help sensor designers at the Physical Electronics Laboratory. The plot on the left shows the electrostatic potential in a capacitive chemical sensor designed by Adrian Kummer.
The symbolic capabilities of Mathematica lend themselves also to the symbolic analysis of electronic circuits, especially in those circumstances where hand calculations can be rather cumbersome, like switched-capacitor filters. Symbolic analysis leads to a parametric description of the circuitry behavior which defines the design space. The decisions taken for the values of the parameters can then be validated with numerical simulations with SPICE or similar programs.
See the publications and the references therein for further information.