Neural interfaces that directly measure brain activity are increasingly employed to elucidate large-scale brain networks and treat intractable neurological disorders. Considering the softness of brain tissue, current efforts to study chronic disorders aim to minimize invasiveness. We discuss recent progress on flexible neural interfaces with high durability under bending and stretching achieved by using organic materials. Multichannel microelectrodes are usually fabricated on thin polymer substrates as sheets and needles to reach superficial and deep brain structures, respectively. An interesting recent trend is the integration of high-density microelectrodes to measure detailed brain functions. The use of numerous measurement points (the current highest values achieved are 62 500 electrodes cm^–2 and 3072 channels) can increase the accuracy of brain state estimation. However, further improvement should be devised for integration in plane considering the density of 250 000 neurons cm^–2 in approximate intervals of 20 μm. Meanwhile, the ultimate goal of improving flexibility in neural interfaces is long-term implantation. Widely used approaches for thinning polymers (∼1 μm) and reducing the rigidity of neural interfaces compromise robustness due to high gas permeability and water uptake. We quantitatively analyze the technical proficiency of flexible neural interfaces in vivo regarding microelectrode integration and robustness. The solution contact impedance, which is a crucial factor in microelectrode miniaturization, is exhaustively surveyed and compared across PEDOT:PSS, Au, Pt, Pt black, IrOx, gels, and other components that should be designed within the permissible source impedance for the measurement device to ensure high-accuracy and low-noise measurements of brain activity in the order of microvolts. Furthermore, we detail a multifunctional neural interface with stretchability, optical transparency, easy intraoperative handling, and flexible transistor implementation for building an active electrode array, providing a new approach for flexible interfaces in neuroscience and neuroengineering.

直接测量大脑活动的神经接口越来越多地用于阐明大规模的大脑网络和治疗顽固性神经系统疾病。考虑到脑组织的柔软性，目前研究慢性疾病的努力旨在最大程度地减少侵入性。我们讨论了使用有机材料在弯曲和拉伸下具有高耐久性的柔性神经界面的最新进展。多通道微电极通常在薄的聚合物基板上制成薄片和针状结构，以分别到达浅表和深部大脑结构。最近一个有趣的趋势是集成高密度微电极以测量详细的大脑功能。使用多个测量点（当前达到的最高值为62 500电极cm ^–2和3072个频道）可以提高大脑状态估计的准确性。然而，进一步的改进等，均应设计用于在平面积分考虑250 000厘米的神经元密度^-2在20近似间隔μ米。同时，提高神经接口灵活性的最终目标是长期植入。广泛使用的方法减薄聚合物（〜1 μ M）和减少神经接口妥协鲁棒性的刚性由于高的气体渗透性和水吸收。我们定量分析了柔性神经接口在体内的技术水平关于微电极的集成和坚固性。溶液接触阻抗是微电极小型化的关键因素，在PEDOT：PSS，Au，Pt，Pt黑，IrOx，凝胶和其他应在允许的测量源阻抗范围内设计的组件中进行了详尽的调查和比较。该设备可确保以微伏为单位对大脑活动进行高精度和低噪声的测量。此外，我们详细介绍了一种多功能神经接口，具有可拉伸性，光学透明性，术中操作简便性以及用于构建有源电极阵列的灵活晶体管，从而为神经科学和神经工程学中的灵活接口提供了一种新方法。