Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, United States of America.
Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America.
J Neural Eng. 2021 Jun 2;18(4). doi: 10.1088/1741-2552/ac00d3.
Our laboratory has proposed chemical stimulation of retinal neurons using exogenous glutamate as a biomimetic strategy for treating vision loss caused by photoreceptor (PR) degenerative diseases. Although our previousstudies using pneumatic actuation indicate that chemical retinal stimulation is achievable, an actuation technology that is amenable to microfabrication, as needed for animplantable device, has yet to be realized. In this study, we sought to evaluate electroosmotic flow (EOF) as a mechanism for delivering small quantities of glutamate to the retina. EOF has great potential for miniaturization.An EOF device to dispense small quantities of glutamate was constructed and its ability to drive retinal output tested in anpreparation of PR degenerate rat retina.We built and tested an EOF microfluidic system, with 3D printed and off-the-shelf components, capable of injecting small volumes of glutamate in a pulsatile fashion when a low voltage control signal was applied. With this device, we produced excitatory and inhibitory spike rate responses in PR degenerate rat retinae. Glutamate evoked spike rate responses were also observed to be voltage-dependent and localized to the site of injection.The EOF device performed similarly to a previously tested conventional pneumatic microinjector as a means of chemically stimulating the retina while eliminating the moving plunger of the pneumatic microinjector that would be difficult to miniaturize and parallelize. Although not implantable, the prototype device presented here as a proof of concept indicates that a retinal prosthetic based on EOF-driven chemical stimulation is a viable and worthwhile goal. EOF should have similar advantages for controlled dispensing of charged neurochemicals at any neural interface.
我们的实验室提出了使用外源性谷氨酸刺激视网膜神经元的化学刺激方法，作为治疗光感受器（PR）退行性疾病引起的视力丧失的仿生策略。虽然我们之前使用气动致动的研究表明化学视网膜刺激是可行的，但仍然需要一种适合植入式设备的微制造的致动技术。在这项研究中，我们试图评估电渗流（EOF）作为向视网膜输送少量谷氨酸的机制。EOF 具有微型化的巨大潜力。我们构建了一种用于分配小量谷氨酸的 EOF 装置，并在 PR 变性大鼠视网膜制备物中测试了其驱动视网膜输出的能力。我们构建并测试了一种 EOF 微流控系统，该系统使用 3D 打印和现成的组件，当施加低电压控制信号时，能够以脉冲方式注入小体积的谷氨酸。使用该装置，我们在 PR 变性大鼠视网膜中产生了兴奋性和抑制性尖峰率响应。还观察到谷氨酸诱发的尖峰率响应与电压有关，并且局限于注射部位。EOF 装置的性能与之前测试的常规气动微注射器相似，是一种化学刺激视网膜的方法，同时消除了气动微注射器的移动柱塞，该柱塞难以微型化和并行化。尽管不可植入，但这里呈现的原型设备作为概念验证表明，基于 EOF 驱动的化学刺激的视网膜假体是一个可行且有价值的目标。EOF 应该在任何神经界面上对带电神经化学物质的受控分配具有类似的优势。
