Biomedical Implants

Biomedical microsystems are one of the most emerging topics in the field of microscale circuits and systems. They can be used in diagnosis, therapy and rehabilitation. Prominent examples are functional electrical stimulators, such as the cardiac pacemaker or the cochlear implant for the deaf, DNA analysis on microarrays, and many more. There main advantage of integrated circuits in these systems is the high degree of functionality, which can be achieved on a very limited amount of space.

This is especially important, if biomedical microsystems are implanted into the human body. Here, the most recent advances are found in neural recorders, which envision the brain-machine interface in the future, and also highly advanced neural stimulators, as the vision prosthesis. Beside stimulation of the human cortex, the retinal implant has received an enormous interest in the last decade. It is a complex microsystem, which is mostly completely implanted into the human eyeball. There it elicts light perception by electrically stimulating the retina. Due to the required high resolution of visual perception, hundreds of stimulation sites are required. Therefore, the use of highly sophisticated integrated electronics for supply generation, data communication, electrical stimulation and more is mandatory.

Our research in biomedical electronics focuses on both, epiretinal (Group Prof. Ortmanns) and subretinal (Group Prof. Rothermel) implants.

Beside, also research is conducted on general circuit techniques for implantable circuits and systems (Group Ortmanns), beyond others on neural recording and stimulation circuitry, electrically safe tissue interfacing, closed loop stimulation electronics, wireless, low-power data communication and real-time control of telemetric energy transfer.

Projects

Transimpedance Amplifiers for Life and Material Science

M. Häberle: Many life and material science applications like Scanning Ion Conductance Microscopy (SICM) and Electrically Detected Magnetic Resonance put demanding constraints on readout electronics. In a SICM experiment a pipette is used to map the surface of soft biological samples. An EDMR experiment is used to derive the efficency of solar cell materials ... [more]

Electrochemical Sensor Integrated Circuits

M. Rajabzadeh: The electrochemical detection of target molecules, the analysis of bioimpedances and the realization in microsystems have received an increasing attention lately. Chronoamperometry (CA), cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS) are the most common methods that are used for the analysis of endogenous and exogenous molecules or electrical properties of tissues ... [more]

Data Compression Techniques for Brain Machine Interfaces

M. Pagin: In last decades development of Brain Machine Interfaces (BMIs) became more and more widespread. The technology allows recording of electrical activity in the brain, to further understand its complex dynamics. But not just for pure research, BMIs offer a bridge between thoughts and actions, robotic prosthesis activated by “thoughts” have already been tested on human patients ... [more]

IC design for an Optical Transcutaneous Telemetric Link

M. Haas: In recent years, brain machine interfaces enable scientists to observe and record neural activity. In some cases neural stimuli can also be applied to partially restore lost neural functionality.  Such interfaces require means of bidirectional wireless communication between the brain implant and the outside world without the risk of inflammation ...  [more]

CMOS Circuits for Multi-Channel, Bidirectional Neural Interfaces

M. Haas, M. Pagin, P. Vogelmann: Bidirectional, neural interfaces are a tool which is widely used in the study of the complex interconnections between neurons within the brain. To understand the activity of neural cells, nervous tissue is first stimulated with a current or voltage signal and afterwards its electrical activity is observed ... [more]

Circuit design for a subretinal stimulator

H. Kaim, S. Gambach, H. Schütz, R. Steinhoff, S. Moll: In this project we develop CMOS circuits optimized for the usage in medical implants. The emphasis is on low-power, optimized silicon area, and optimized performance ... [more]