For long-term biocompatibility and performance, implanted probes need to further reduce their size and mechanical stiffness to match that of the surrounding cells, which, however, makes accurate and minimally invasive insertion operations difficult due to lack of rigidity and brings additional complications in assembling and surgery. Here, we report a scalable fabrication framework of implantable probes utilizing biodegradable sacrificial layers to address this challenge. Briefly, the integrated biodegradable sacrificial layer can dissolve in physiological fluids shortly after implantation, which allows the in situ formation of functional ultrathin film structures off of the initial small and rigid supporting backbone. We show that the dissolution of this layer does not affect the viability and excitability of neuron cells in vitro. We have demonstrated two types of probes that can be used out of the box, including (1) a compact probe that spontaneously forms three-dimensional bend-up devices only after implantation and (2) an ultraflexible probe as thin as 2 μm attached to a small silicon shaft that can be accurately delivered into the tissue and then get fully released in situ without altering its shape and position because the support is fully retracted. We have obtained a >93% yield of the bend-up structure, and its geometry and stiffness can be systematically tuned. The robustness of the ultraflexible probe has been tested in tissue-mimicking agarose gels with <1% fluctuation in the test resistance. Our work provides a general strategy to prepare ultrasmall and flexible implantable probes that allow high insertion accuracy and minimal surgical damages with the best biocompatibility.

中文翻译：

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具有生物可降解牺牲层的可植入超薄材料和柔性探针的可扩展制造框架

为了获得长期的生物相容性和性能，植入式探针需要进一步减小其尺寸和机械刚度，以匹配周围细胞，但是由于缺乏刚度，使得精确且微创的插入操作变得困难，并且组装时带来了更多的复杂性和手术。在这里，我们报告了利用可生物降解的牺牲层来解决这一挑战的可植入探针的可扩展制造框架。简而言之，集成的可生物降解的牺牲层可以在植入后不久溶解在生理流体中，从而可以从最初的小而刚性的支撑主链上原位形成功能性超薄膜结构。我们表明该层的溶解不会影响神经元细胞在体外的活力和兴奋性。我们已经展示了两种可以直接使用的探针，包括（1）紧凑的探针，仅在植入后才能自发形成三维弯曲装置；（2）附着至2μm的超柔性探针一个小的硅轴，可以将其准确地传送到组织中，然后在不改变其形状和位置的情况下就地完全释放，因为支撑架已完全缩回。我们已经获得了大于93％的弯曲结构的收率，并且可以系统地调整其几何形状和刚度。超柔软探针的坚固性已在模拟组织的琼脂糖凝胶中进行了测试，测试阻力波动小于1％。