Abdo Ammar, Sahin Mesut
Biomedical Engineering Department, New Jersey Institute of Technology, Newark, NJ 07102 USA.
IEEE Trans Biomed Circuits Syst. 2011 Apr 5;2011(99):1. doi: 10.1109/TBCAS.2011.2114882.
Neural microstimulation is becoming a powerful tool for the restoration of impaired functions in the central nervous system. Microelectrode arrays with fine wire interconnects have traditionally been used in the development of these neural prosthetic devices. However, these interconnects are usually the most vulnerable part of the neuroprosthetic implant that can eventually cause the device to fail. In this paper, we investigate the feasibility of floating-light-activated microelectrical stimulators (FLAMES) for wireless neural stimulation. A computer model was developed to simulate the micro stimulators for typical requirements of neural activation in the human white and gray matters. First, the photon densities due to a circular laser beam were simulated in the neural tissue at near-infrared (NIR) wavelengths. Temperature elevation in the tissue was calculated and the laser power was retrospectively adjusted to 325 and 250 mW/cm(2) in the gray and white matters, respectively, to limit ΔT to 0.5 °C. Total device area of the FLAMES increased with all parameters considered but decreased with the output voltage. We conclude that the number of series photodiodes in the device can be used as a free parameter to minimize the device size. The results suggest that floating, optically activated stimulators are feasible at submillimeter sizes for the activation of the brain cortex or the spinal cord.
神经微刺激正成为恢复中枢神经系统受损功能的有力工具。传统上，带有细线互连的微电极阵列一直用于这些神经假体装置的开发。然而，这些互连通常是神经假体植入物中最脆弱的部分，最终可能导致装置失效。在本文中，我们研究了用于无线神经刺激的浮动光激活微电刺激器（FLAMES）的可行性。开发了一个计算机模型来模拟微刺激器，以满足人类白质和灰质中神经激活的典型要求。首先，模拟了近红外（NIR）波长下神经组织中圆形激光束产生的光子密度。计算了组织中的温度升高，并将激光功率分别追溯调整为灰质中的325 mW/cm²和白质中的250 mW/cm²，以将ΔT限制在0.5°C。考虑所有参数后，FLAMES的总装置面积增加，但随输出电压减小。我们得出结论，装置中串联光电二极管的数量可作为一个自由参数，以最小化装置尺寸。结果表明，对于激活大脑皮层或脊髓，亚毫米尺寸的浮动光激活刺激器是可行的。
