Microfluidic concentration gradient generators (µ-CGGs) have been utilized to identify optimal drug compositions through antimicrobial susceptibility testing (AST) for the treatment of antimicrobial-resistant (AMR) infections. Conventional µ-CGGs fabricated via photolithography-based micromachining processes, however, are fundamentally limited to two-dimensional fluidic routing, such that only two distinct antimicrobial drugs can be tested at once. This work addresses this limitation by employing Multijet-3D-printed microchannel networks capable of fluidic routing in three dimensions to generate symmetric multidrug concentration gradients. The three-fluid gradient generation characteristics of the fabricated 3D µ-CGG prototype were quantified through both theoretical simulations and experimental validations. Furthermore, the antimicrobial effects of three highly clinically relevant antibiotic drugs, tetracycline, ciprofloxacin, and amikacin, were evaluated via experimental single-antibiotic minimum inhibitory concentration (MIC) and pairwise and three-way antibiotic combination drug screening (CDS) studies against model antibiotic-resistant Escherichia coli bacteria. As such, this 3D µ-CGG platform has great potential to enable expedited combination AST screening for various biomedical and diagnostic applications.

微流体浓度梯度发生器 ( µ- CGGs) 已被用于通过抗微生物药敏试验 (AST) 确定最佳药物成分，以治疗抗微生物药物 (AMR) 感染。然而，通过基于光刻的微加工工艺制造的传统µ -CGG 从根本上限于二维流体路径，因此一次只能测试两种不同的抗菌药物。这项工作通过采用能够在三个维度上进行流体路由的 Multijet-3D 打印微通道网络来生成对称的多药浓度梯度，从而解决了这一限制。制造的 3D µ的三流体梯度生成特性-CGG 原型通过理论模拟和实验验证进行量化。此外，通过针对模型抗生素的实验性单一抗生素最低抑菌浓度 (MIC) 和成对和三效抗生素联合药物筛选 (CDS) 研究，评估了三种临床高度相关的抗生素药物四环素、环丙沙星和阿米卡星的抗菌作用。 - 耐药大肠杆菌。因此，这个 3D µ -CGG 平台具有极大的潜力，可以为各种生物医学和诊断应用加速组合 AST 筛选。