Rieger Stefan B, Pfau Jennifer, Stieglitz Thomas, Asplund Maria, Ordonez Juan S
Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Köhler-Allee 102, 79110 Freiburg, Germany.
Cortec GmbH, Georges-Köhler Allee 010, 79110 Freiburg, Germany.
Sensors (Basel). 2016 Dec 30;17(1):59. doi: 10.3390/s17010059.
There has been substantial progress over the last decade towards miniaturizing implantable microelectrodes for use in Active Implantable Medical Devices (AIMD). Compared to the rapid development and complexity of electrode miniaturization, methods to monitor and assess functional integrity and electrical functionality of these electrodes, particularly during long term stimulation, have not progressed to the same extent. Evaluation methods that form the gold standard, such as stimulus pulse testing, cyclic voltammetry and electrochemical impedance spectroscopy, are either still bound to laboratory infrastructure (impractical for long term in vivo experiments) or deliver no comprehensive insight into the material's behaviour. As there is a lack of cost effective and practical predictive measures to understand long term electrode behaviour in vivo, material investigations need to be performed after explantation of the electrodes. We propose the analysis of the electrode and its environment in situ, to better understand and correlate the effects leading to electrode failure. The derived knowledge shall eventually lead to improved electrode designs, increased electrode functionality and safety in clinical applications. In this paper, the concept, design and prototyping of a sensor framework used to analyse the electrode's behaviour and to monitor diverse electrode failure mechanisms, even during stimulation pulses, is presented. We focused on the electronic circuitry and data acquisition techniques required for a conceptual multi-sensor system. Functionality of single modules and a prototype framework have been demonstrated, but further work is needed to convert the prototype system into an implantable device. In vitro studies will be conducted first to verify sensor performance and reliability.
在过去十年中，用于有源植入式医疗设备（AIMD）的植入式微电极小型化取得了重大进展。与电极小型化的快速发展和复杂性相比，监测和评估这些电极功能完整性和电功能的方法，特别是在长期刺激期间，并没有取得同样程度的进展。构成金标准的评估方法，如刺激脉冲测试、循环伏安法和电化学阻抗谱，要么仍然依赖实验室基础设施（对于长期体内实验不实用），要么无法全面洞察材料的行为。由于缺乏经济有效且实用的预测措施来了解电极在体内的长期行为，因此需要在电极取出后进行材料研究。我们建议对电极及其周围环境进行原位分析，以更好地理解并关联导致电极失效的各种影响因素。由此获得的知识最终应能改进电极设计，提高电极在临床应用中的功能和安全性。本文介绍了一种传感器框架的概念、设计和原型制作，该框架用于分析电极行为并监测各种电极失效机制，甚至在刺激脉冲期间也能进行监测。我们重点关注了概念性多传感器系统所需的电子电路和数据采集技术。单个模块和原型框架的功能已经得到验证，但仍需进一步开展工作将原型系统转化为可植入设备。首先将进行体外研究以验证传感器的性能和可靠性。
