The realization of optically active structures with direct‐write printing has been challenging, particularly in spatially constrained microfluidic devices which are essential for point‐of‐care (POC) applications. The existing techniques are limited by resolution, accessibility, and multistep fabrication constraints. “Point‐and‐shoot” strategies to achieve site‐specific fabrication of optically active Ag rings and on‐demand targeted surface‐enhanced optical spectroscopy are reported. Stable microbubbles over an Au nanoisland (AuNI) substrate are generated using a continuous‐wave laser at low power (≈0.5 mW µm⁻²). Analytical modeling of bubble generation process substantiates the evolution of ring morphology and its power dependence. The tunable Ag rings exhibit surface plasmon resonances in the mid‐IR regime from 3.8 to 4.6 µm, while the AuNI shows visible region response. The Ag ring over the AuNI imparts intensified surface‐enhanced Raman spectroscopy (SERS) activity owing to amplified hot spots at Ag ring/AuNI interface. As an example, SERS and surface‐enhanced infrared spectroscopy of rhodamine 6G, crystal violet, and 2,4,6‐trinitrotoluene molecules, respectively, are demonstrated. The applicability of this technique to perform in situ fabrication and SERS sensing in microfluidic channels is shown. Using a simple in situ approach toward optically active structures, our technique can synergize multiple surface‐enhanced optical spectroscopies to facilitate POC applications.

中文翻译：

---

金属环阵列的“即射”合成和表面增强光谱

通过直写印刷实现光学活性结构一直是一项挑战，特别是在空间受限的微流体设备中，这种设备对于即时医疗（POC）应用至关重要。现有技术受到分辨率，可访问性和多步骤制造限制的限制。据报导了“即取即拍”策略，可实现针对现场的光学活性银环的制造以及按需定向的目标表面增强光谱学。使用连续波激光以低功率（≈0.5mW µm ^-2）在金纳米岛（AuNI）基板上产生稳定的微气泡）。气泡产生过程的分析模型证实了环形态的演变及其功率依赖性。可调谐的Ag环在中红外范围从3.8到4.6 µm处表现出表面等离子体共振，而AuNI则显示出可见的区域响应。由于Ag环/ AuNI界面处的热点放大，AuNI上方的Ag环赋予了增强的表面增强拉曼光谱（SERS）活性。例如，分别展示了若丹明6G，结晶紫和2,4,6-三硝基甲苯分子的SERS和表面增强红外光谱。显示了该技术在微流体通道中进行原位制造和SERS传感的适用性。使用简单的原位处理光学活性结构的方法，