Advanced Technology Development Centre, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
Biomed Microdevices. 2017 Aug 25;19(4):75. doi: 10.1007/s10544-017-0221-0.
Understanding of the neural response to electrical stimulation requires simultaneous recording from the various neurons of retina. Electrodes form the physical interface with the neural or retinal tissue. Successful retinal stimulation and recording demands conformal integration of these electrodes with the soft tissue to ensure establishment of proper electrical connection with the excitable tissue. Mechanical impedance of polydimethylsiloxane (PDMS) being compliant with that of retinal tissue, offers excellent potential as a substrate for metal electrodes. In this paper, Cr/Au micro electrodes with 200 μm diameter were fabricated on rigid and flexible PDMS substrates under crack free condition. Spontaneous buckling of thin films over PDMS substrates improved electrode performance circumventing the fabrication issues faced over a buckled surface. Individual electrodes from the multielectrode arrays (MEAs) were examined with electrochemical impedance spectroscopy and cyclic voltammetry. Controlled fabrication process as described here generates buckles in the metal films leading to increased electrode surface area that increases the charge storage capacity and decreases the interface impedance of the metal electrodes. At 1 kHz, impedance was reduced from 490 ± 27 kΩ to 246 ± 19 kΩ and charge storage capacity was increased from 0.40 ± 0.87 mC/cm to 2.1 ± 0.87 mC/cm. Neural spikes recorded with PDMS based electrodes from isolated retina also contained less noise as indicated by signal to noise ratio analysis. The present study established that the use of PDMS as a substrate for MEAs can enhance the performance of any thin film metal electrodes without incorporation of any coating layers or nanomaterials.
理解电刺激对神经元的反应需要同时记录视网膜的各种神经元。电极与神经或视网膜组织形成物理接口。成功的视网膜刺激和记录需要这些电极与软组织的共形集成，以确保与可兴奋组织建立适当的电连接。聚二甲基硅氧烷 (PDMS) 的机械阻抗与视网膜组织的阻抗相匹配，为金属电极提供了极好的潜在应用。在本文中，在无裂纹的条件下，在刚性和柔性 PDMS 衬底上制造了直径为 200 μm 的 Cr/Au 微电极。PDMS 衬底上的薄膜的自发屈曲改善了电极性能，避免了在屈曲表面上面临的制造问题。通过电化学阻抗谱和循环伏安法检查了来自多电极阵列 (MEA) 的单个电极。如前所述，受控的制造工艺会导致金属膜中的屈曲，从而增加电极表面积，增加金属电极的电荷存储容量并降低界面阻抗。在 1 kHz 时，阻抗从 490 ± 27 kΩ 降低到 246 ± 19 kΩ，电荷存储容量从 0.40 ± 0.87 mC/cm 增加到 2.1 ± 0.87 mC/cm。用基于 PDMS 的电极从分离的视网膜记录的神经尖峰也包含较少的噪声，如信噪比分析所示。本研究表明，将 PDMS 用作 MEA 的基底可以在不引入任何涂层或纳米材料的情况下增强任何薄膜金属电极的性能。
