Thil M A, Gérard B, Jarvis J C, Delbeke J
Neural Rehabilitation Engineering Laboratory, Université Catholique de Louvain, Medical School, Brussels, Belgium.
Med Biol Eng Comput. 2005 Jul;43(4):528-34. doi: 10.1007/BF02344736.
Implantable stimulators are needed for chronic electrical stimulation of nerves and muscles in experimental studies. The device described exploits the versatility of current microcontrollers for stimulation and communication in a miniature implant. Their standard outputs can provide the required selectable constant-current sources. In this device, pre-programmed stimulation paradigms were selected by transcutaneous light pulses. The potential of a programmable integrated circuit (PIC) was thus exploited. Implantable devices must be biocompatible. A novel encapsulation method that require no specialised equipment and that used two classical encapsulants, silicone and Teflon was developed. It was tested for implantation periods of up to four weeks. A novel way to estimate electrode impedance in awake animals is also presented. It was thus possible to follow the evolution of the nerve-electrode interface and, if necessary, to adjust the stimulation parameters. In practice, the electrode voltage at the end of a known constant-current pulse was measured by the PIC. The binary coded value was then indicated to the user as a series of muscle twitches that represented the binary value of the impedance measurement. This neurostimulator has been successfully tested in vitro and in vivo. Thresholds and impedance values were chronically monitored following implantation of a self-sizing spiral cuff electrode. Impedance variations in the first weeks could reflect morphological changes usually observed after the implantation of such electrodes.
在实验研究中，慢性神经和肌肉电刺激需要植入式刺激器。所描述的装置利用了当前微控制器在微型植入物中的刺激和通信多功能性。其标准输出可以提供所需的可选恒流源。在该装置中，通过经皮光脉冲选择预编程的刺激模式。从而利用了可编程集成电路（PIC）的潜力。植入式设备必须具有生物相容性。开发了一种新颖的封装方法，该方法不需要专门设备，且使用了两种经典封装材料，即硅酮和聚四氟乙烯。对其进行了长达四周的植入期测试。还提出了一种在清醒动物中估计电极阻抗的新方法。因此，有可能跟踪神经 - 电极界面的演变，并在必要时调整刺激参数。在实际操作中，PIC测量已知恒流脉冲结束时的电极电压。然后将二进制编码值以一系列肌肉抽搐的形式显示给用户，这些肌肉抽搐代表阻抗测量的二进制值。这种神经刺激器已在体外和体内成功测试。在植入自适应螺旋袖带电极后，长期监测阈值和阻抗值。最初几周的阻抗变化可以反映出通常在此类电极植入后观察到的形态变化。
