A NOVEL ACTIVE ELECTRODE BOOK FOR MULTI-FUNCTIONAL RESTORATION AFTER SPINAL CORD INJURY

研究表明，电刺激椎管内的腰骶前后神经根，可使严重脊髓损伤患者恢复多种功能，改善其健康状况和生活质量。这需要使用许多刺激电极。然而，长期使用植入式神经根刺激器的一个主要问题是安全性。在故障条件下，用于刺激的电极可能腐蚀或电解组织中的水，导致神经损伤。通过在每个刺激电极上串联一个大的阻塞电容器（在uF范围内），通常可以减少这种危险并使其成为可接受的。这些电容器决定了刺激器的物理尺寸，因为太大而无法装入椎管。因此，现有的植入式装置有一个皮下刺激器，通过电缆连接到鞘内神经根电极。外科医生认为增加穿过硬脑膜的电缆的数量是不可接受的手术风险，这限制了可以获得的功能的数量。这是一个严重的缺点，因为有许多有价值的功能已经被证明是可能的。克服这一限制的一种方法是在靠近电极的地方产生刺激电流，在硬脑膜内，但这意味着电子封装的尺寸必须非常小，但它必须仍然是安全的。我们已经发明了一种方法，允许我们使用小至50pF的阻塞电容器，使整个刺激器可以集成在单个硅芯片上，并且仍然是故障安全的。在本研究中，我们提出以活性电极本的形式开发该技术，该技术可直接植入人体椎管中，用于脊髓损伤后的多功能修复。此外，我们将开发用于小型植入设备的新的最小集成电路密封方法，以及一种新的微加工方法，用激光将铂电极从箔中切割出来并将其连接到刺激芯片上。原型有源电极书将被生产出来，用于病人的后续试点研究。该项目是伦敦大学学院、爱尔兰廷德尔国家研究所和德国弗赖堡大学之间的多学科合作项目。

It has been shown that electrical stimulation of the lumbar and sacral anterior and posterior nerve roots in the spinal canal can restore many functions to people with serious spinal cord injury, to improve their health and quality of life. This requires the use of many stimulating electrodes. However, a major concern in implanted nerve root stimulators for chronic use with patients is safety. Electrodes that are meant for stimulation could, under fault conditions, corrode or electrolyse water in the tissue causing nerve damage. This danger is usually diminished and made acceptable by placing a large blocking capacitor (in the uF range) in series with each stimulating electrode. These capacitors determine the physical size of the stimulator which is too large to fit in the spinal canal. Thus, existing implanted devices have a subcutaneous stimulator connected with cables to the intra-thecal nerve root electrodes. Surgeons consider that it is an unacceptable surgical risk to increase the number of cables which pass through the dura, and this limits the number of functions that can be obtained. This is a serious disadvantage given the number of valuable functions that have been shown to be possible. One way to overcome this limitation is to generate the stimulation currents close to the electrodes, inside the dura, but that means that the size of the electronic package must be very small and yet it must still be safe. We have invented a method which allows us to use blocking capacitors as small as 50pF, so that the complete stimulator can be integrated on a single silicon chip, and still be fail-safe. In this research, we propose to develop the technology in the form of an active electrode book that may be directly implanted in the human spinal canal for multi-functional restoration after spinal cord injury. In addition, we will develop new minimal integrated circuit sealing methods for use in small implanted devices, and a new micro-fabrication method to cut the platinum electrodes out of foil with a laser and join them to the stimulator chip. Prototype active electrode books will be produced that will be made available for subsequent pilot studies in patients. The project is a multidisciplinary collaboration between University College London, the Tyndall National Institute in Ireland, and the University of Freiburg in Germany.