Electronic micro and nano-devices are suitable tools to monitor the activity of many individual neurons over mesoscale networks. However the inorganic materials currently used in microelectronics are barely accepted by neural cells and tissues, thus limiting both the sensor lifetime and efficiency. In particular, penetrating intracortical probes face high failure rate because of a wide immune response of cells and tissues. This adverse reaction called gliosis leads to the rejection of the implanted probe after few weeks and prevent long-lasting recordings of cortical neurons. Such acceptance issue impedes the realization of many neuro-rehabilitation projects. To overcome this, graphene and related carbon-based materials have attracted a lot of interest regarding their positive impact on the adhesion and regeneration of neurons, and their ability to provide high-sensitive electronic devices, such as graphene field effect transistor (G-FET). Such devices can also be implemented on numerous suitable substrates including soft substrates to match the mechanical compliance of cells and tissues, improving further the biocompatibility of the implants. Thus, using graphene as a coating and sensing device material could significantly enhance the acceptance of intracortical probes. However, such a thin monolayer of carbon atoms could be teared off during manipulation and insertion within the brain, and could also display degradation over time. In this work, we have investigated the ability to protect graphene with a natural, biocompatible and degradable polymeric film derivated from hyaluronic acid (HA). We demonstrate that HA-based coatings can be deposited over a wide range of substrates, including intracortical probes and graphene FET arrays without altering the underlying device material, its biocompatibility and sensitivity. Moreover, we show that this coating can be monitored in-situ by quantifying the number of deposited charges with the G-FET arrays. The reported graphene functionalization offers promising alternatives for improving the acceptance of various neural interfaces.

中文翻译：

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为石墨烯神经电子学引入仿生涂层：面向体内应用

电子微型和纳米设备是监测中尺度网络上许多单个神经元活动的合适工具。然而，目前用于微电子的无机材料几乎不被神经细胞和组织所接受，从而限制了传感器的寿命和效率。特别是，由于细胞和组织的广泛免疫反应，穿透皮质内探针面临高失败率。这种称为神经胶质增生的不良反应会导致植入的探针在几周后被拒绝，并阻止皮层神经元的长期记录。这种接受问题阻碍了许多神经康复项目的实现。为了克服这一点，石墨烯和相关的碳基材料因其对神经元粘附和再生的积极影响而引起了很多兴趣，以及它们提供高灵敏度电子器件的能力，例如石墨烯场效应晶体管（G-FET）。这种装置也可以在许多合适的基底上实施，包括软基底，以匹配细胞和组织的机械顺应性，进一步提高植入物的生物相容性。因此，使用石墨烯作为涂层和传感装置材料可以显着提高皮质内探针的接受度。然而，如此薄的碳原子单层可能会在操纵和插入大脑期间被撕下，并且随着时间的推移也会出现退化。在这项工作中，我们研究了使用源自透明质酸 (HA) 的天然、生物相容性和可降解聚合物膜保护石墨烯的能力。我们证明了基于 HA 的涂层可以沉积在各种基材上，包括皮质内探针和石墨烯 FET 阵列，而不会改变底层设备材料、其生物相容性和灵敏度。此外，我们表明，可以通过使用 G-FET 阵列量化沉积电荷的数量来现场监测这种涂层。报道的石墨烯功能化为提高各种神经接口的接受度提供了有希望的替代方案。