Carbon based electrodes suitable for integration with CMOS readout electronics are of great importance for a variety of emerging applications. In this study, we have looked into the prerequisites for the optimized pyrolytic conversion of 3D printed polymer microstructures and nanostructures with the goal of developing sensing electrodes for a lab-on-CMOS electrochemical system. As a result, we identified conditions for a sequence of anneals in oxidative and inert environments that yield carbonized structures on metallized substrates with improved shape retention, while also providing electrical insulation of the surrounding metal stack. We demonstrated that titanium metal layers can be conveniently used to form electrically insulating titanium oxide on the substrate outside the carbonized structures in a self-aligned fashion. However, significant shrinkage of polymer structures formed by 3D printing or stereolithography is inevitable during their pyrolysis. Furthermore, the catalytically active titanium oxide present during initial stages of carbonization leads to additional loss of carbon and significant artifacts in the resulting structures. To minimize these adverse effects of titanium oxide on the shape retention of the carbonized structures, we developed an optimized processing sequence. Various processing steps in this sequence were characterized in terms of their effects on titanium oxide growth and geometrical changes in the 3D printed structures, while impedance and Raman spectroscopy were performed to evaluate their degree of pyrolytic conversion and, therefore, potential for electrochemical sensing.

中文翻译：

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用于 CMOS 兼容电化学传感器的 3D 打印聚合物结构的碳化

适合与 CMOS 读出电子设备集成的碳基电极对于各种新兴应用非常重要。在这项研究中，我们研究了优化 3D 打印聚合物微结构和纳米结构的热解转化的先决条件，目的是为实验室 CMOS 电化学系统开发传感电极。因此，我们确定了在氧化和惰性环境中进行一系列退火的条件，这些条件在金属化基材上产生碳化结构，形状保持性得到改善，同时还为周围的金属叠层提供电绝缘。我们证明了钛金属层可以方便地用于以自对准方式在碳化结构外部的基板上形成电绝缘氧化钛。然而，在热解过程中，通过 3D 打印或立体光刻形成的聚合物结构的显着收缩是不可避免的。此外，在碳化的初始阶段存在的催化活性氧化钛会导致碳的额外损失和所得结构中的显着伪影。为了最大限度地减少氧化钛对碳化结构形状保持的不利影响，我们开发了优化的加工顺序。该序列中的各种处理步骤的特征在于它们对 3D 打印结构中氧化钛生长和几何变化的影响，同时进行阻抗和拉曼光谱以评估它们的热解转化程度，从而评估电化学传感的潜力。