Multifunctional, MEMS-based neural interfaces developed in the framework of the European Project NeuroProbes

Abstract: The fundamental understanding of neuronal operations relies on electrical recordings of single neuron activity, traditionally performed using single wire electrodes or small ensembles of electrodes. This limitation in the number of recording sites can be overcome with multi-electrode probes based on fabrication technologies used for integrated circuits (IC) and microelectromechanical systems (MEMS). These electrode systems enable the arrangement of electrodes as two-dimensional (2D) and three-dimensional (3D) arrays.

NeuroProbes, a multinational research project funded by the European Commission with the participation of 14 institutions in 10 European countries, addresses the development of multi-functional multi-electrode arrays for neural recording and stimulation. Technological, biological and industrial partners cooperate within NeuroProbes to realise progressively complex system architectures with continuous feedback from biological experiments, ultimately aiming for commercial exploitation. NeuroProbes is based on a unique microsystem integration solution to enable the modular integration of diverse features into a common platform forming a 3D probe array. This solution combines recording and stimulating electrodes with microfluidic functionality for drug delivery, biosensors to detect specific chemicals in the brain as well as CMOS-based electronics to realize high density electrode arrays with a pitch of 40 µm along the entire probe shaft. The functional subcomponents, i.e. micro electrode and electronics, microfluidic system and biosensor, are integrated on needle-like silicon shafts with lengths of up to 8 mm. These needles are assembled to comb-like structures which in turn are inserted in a common backbone forming 3D arrays. The electrical interconnection of the probes with external measurement equipment is performed using highly flexible ribbon cables with a thickness of 10 µm.

Bio: Patrick Ruther studied physics at the University of Konstanz, Germany, and received the Ph.D. degree in mechanical engineering from the University of Karlsruhe, Germany, in 1996. Between 1996 and 1998, he joined the Institute of Microstructure Technology IMT (Research Centre, Germany) as a Postdoctoral Fellow where he was responsible for industrial projects on microoptical components based on the LIGA-technology. Since October 1998, he has been an Assistant / Senior Scientist and Group Leader at the Microsystem Materials Laboratory (MML) of the Department of Microsystems Engineering (IMTEK), Freiburg, Germany, and a Lecturer at the Faculty of Engineering, University of Freiburg, Germany. He teaches classes on (i) Dry etching, (ii) Advanced Silicon Technologies and (iii) Test structures and methods for ICs and MEMS. His research focus is on the design, fabrication and characterization of CMOS-compatible microelectromechanical systems, i.e. integrated stress sensing systems (among others a 3D tactile sensor system for ZEISS), and the development of new micromachining methods for (bio-)medical applications (among others microneedles arrays for allergy testing and surface electromyography). He is technology coordinator of the European research project /NeuroProbes/ developing multifunctional microelectrode arrays for cerebral applications