Thilo Krüger

Measuring epileptogenicity in kainic acid injected rats

The present work aims at improving the validation of therapeutic approaches to treat temporal lobe epilepsy. Todays antiepileptic drugs perform only poorly for this form of epilepsy, and electrical stimulation might be an alternative for these patients. Finding the optimal stimulation parameters, however, is difficult as the underlying mechanisms, both of the disease and the stimulation procedure, and even the evaluation of the therapeutic effect are still poorly understood. Here we used a method to obtain a quantitative measure - the relative phase clustering index (rPCI) - of the epileptogenicity of a brain region in a simple and straightforward way.

Possibilities offered by implantable miniaturized cuff-electrodes for insect neurophysiology

Recent advances in microsystems technology led to a miniaturization of cuff-electrodes, which suggests these electrodes not just for long-term neuronal recordings in mammalians, but also in medium-sized insects. In this study we investigated the possibilities offered by cuff-electrodes for neuroethology using insects as a model organism. The implantation in the neck of a tropical bushcricket resulted in high quality extracellular nerve recordings of different units responding to various acoustic, vibratory, optical and mechanical stimuli. In addition, multi-unit nerve activity related to leg movements was recorded in insects walking on a trackball. A drawback of bi-polar nerve recordings obtained during tethered flight was overlay of nerve activity with large amplitude muscle potentials. Interestingly, cuff-electrode recordings were robust to withstand walking and flight activity so that good quality nerve recordings were possible even three days after electrode implantation. Recording multi-unit nerve activity in intact insects required an elaborate spike sorting algorithm in order to discriminate neuronal units responding to external stimuli from background activity. In future, a combination of miniaturized cuff-electrodes and light-weight amplifiers equipped with a wireless transmitter will allow the investigation of neuronal processes underlying natural behavior in freely moving insects. By this means cuff-electrodes may contribute to the development of realistic neuronal models simulating neuronal processes underlying natural insect behavior, such like mate choice and predator avoidance.

Interactive Implants: Ethical, legal and social implications

Abstract The use of intelligent implants and prostheses offers significant advances for optimizing medical treatment methods and is combined with an increasing technological modification of human body. This raises many exciting questions concerning law, ethics and social implications: Does the use of these techniques stay in line with our legal system and if yes, can the technical use be limited by governmental restrictions under certain conditions? Have moral values to be incorporated into technical artifacts? If machines are recreated from human beings, do they have to be provided with a legal subjectivity? Medical devices must be compatible with a high level of protection of health and safety. Therefore challenges, which are consequences of the indeterminate behaviour and the autonomous learning abilities of artificial intelligence, have to be faced. For avoidance of any hazards for legally protected rights medical product manufacturers have to assume legal duties, which affect construction, instruction and product development. For medical professionals there are also liabilities of maintenance measures and technical control that have to be accomplished. Associated with the use of intelligent medical devices is the processing of personal data on health. Health data have a high potential for misuse and discrimination and therefore they’re in need of special protection, particularly with regard to the development of “Big Data”, “Ubiquitous computing”, “Internet of Things” and constantly increasing cybercrime. If damages are suffered from the use of intelligent medical devices, difficulties in determining infringing acts, causality and culpability occur, especially because of the missing view into the technical progress of decision-making. It has to be explored, if the current liability law is able to assign responsibility adequately, otherwise there has to be found an appropriate concept for liability.

Electrophoretic deposition of dielectric film on stimulation electrodes for the use in intraoperative neuromonitoring

Abstract Electrophoretic deposition (EPD) is a material processing technology which uses direct current (DC) voltage to deposit thin layers on a metallic substrate. EPD is a promising coating technology for medical devices due to its advantages such as thin homogenous layers and a broad range of usable substrates. The objective of this paper is to demonstrate how EPD can be deployed successfully to apply an insulation layer on a stimulation electrode. The Mapping suction probe by inomed Medizintechnik GmbH, Germany, was coated in this investigation. The unique feature of this product is that it combines both a surgical vacuum and a stimulation probe and is used for brain tumour resection. As for the insulation layer, ethylene chlorotrifluoroethylene (ECTFE) was chosen because of its good dielectric and biocompatible properties. ECTFE particles (Halar®6514, Solvay Specialty Polymer, Italy) were mixed with a solvent (Novec™ 7100DL Engineered Fluid, 3M™) to form a suspension. The coating process was partly automatized to ensure good repeatability and reproducibility. For coating, the stimulation probe was immersed in the suspension so that the counter electrode, a stainless-steel net, surrounded it equidistantly. A heat treatment of the coated device in an oven (FED56, Binder, Germany) was required afterwards to melt the deposited polymer particles. After the heat treatment, a glossy black layer (layer thickness 42 μm) was observed on the substrate. A smooth and homogenous surface confirmed that the coating is suitable for surgical application. However, due to a high evaporation rate of the solvent, the ratio of particles and solvent changes and the coating process will have to be controlled in the future to achieve a stable process. Further advantages of EPD such as short processing time, straightforward process flow and scalability enables high production quantities which is attractive for industrial application. EPD might be a promising coating technology for medical devices in the future.